[CI] Add more checks (#43)

.drone.yml

@@ -28,6 +28,7 @@ pipeline:
       # - make got-swag # Commented out until we figured out how to get this working on drone
       - make ineffassign-check
       - make misspell-check
+      - make goconst-check
       - make build
     when:
       event: [ push, tag, pull_request ]

Featurecreep.md

@@ -124,3 +124,11 @@ Sorry for some of them being in German, I'll tranlate them at some point.
 * [ ] Mgl., dass die Instanz geschlossen ist, also sich keiner registrieren kann, und man sich einloggen muss
 * [ ] mgl. zum Emailmaskieren haben (in den Nutzereinstellungen, wenn man seine Email nicht an alle Welt rausposaunen will)
 * [ ] Mgl. zum Accountlöschen haben (so richtig krass mit emailverifiezierung und dass alle Privaten Listen gelöscht werden und man alle geteilten entweder wem übertragen muss oder  auf privat stellen)
+
+### Linters
+
+* [x] goconst
+* [ ] Gosimple -> waiting for mod
+* [ ] Staticcheck -> waiting for mod
+* [ ] unused -> waiting for mod
+* [ ] gosec -> waiting for mod

Makefile

@@ -187,3 +187,39 @@ gocyclo-check:
 		go install $(GOFLAGS) github.com/fzipp/gocyclo; \
 	fi
 	for S in $(GOFILES); do gocyclo -over 14 $$S || exit 1; done;
+
+.PHONY: gosimple-check
+gosimple-check:
+	@hash gosimple > /dev/null 2>&1; if [ $$? -ne 0 ]; then \
+		go get honnef.co/go/tools/cmd/gosimple; \
+	fi
+	for S in $(PACKAGES); do gosimple $$S || exit 1; done;
+
+.PHONY: static-check
+static-check:
+	@hash gocyclo > /dev/null 2>&1; if [ $$? -ne 0 ]; then \
+		go get honnef.co/go/tools/cmd/staticcheck; \
+	fi
+	staticcheck;
+
+.PHONY: unused-check
+unused-check:
+	@hash unused > /dev/null 2>&1; if [ $$? -ne 0 ]; then \
+		go get honnef.co/go/tools/cmd/unused; \
+	fi
+	unused;
+
+.PHONY: gosec-check
+gosec-check:
+	@hash ./bin/gosec > /dev/null 2>&1; if [ $$? -ne 0 ]; then \
+		curl -sfL https://raw.githubusercontent.com/securego/gosec/master/install.sh | sh -s 1.2.0; \
+	fi
+	for S in $(PACKAGES); do ./bin/gosec $$S || exit 1; done;
+
+.PHONY: goconst-check
+goconst-check:
+	@hash goconst > /dev/null 2>&1; if [ $$? -ne 0 ]; then \
+		go get github.com/jgautheron/goconst/cmd/goconst; \
+	fi
+	for S in $(PACKAGES); do goconst $$S || exit 1; done;
+

go.mod

@@ -23,7 +23,6 @@ require (
 	github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc
 	github.com/asaskevich/govalidator v0.0.0-20180720115003-f9ffefc3facf
 	github.com/client9/misspell v0.3.4
-	github.com/cweill/gotests v1.5.2 // indirect
 	github.com/dgrijalva/jwt-go v3.2.0+incompatible
 	github.com/fzipp/gocyclo v0.0.0-20150627053110-6acd4345c835
 	github.com/garyburd/redigo v1.6.0 // indirect
@@ -39,7 +38,9 @@ require (
 	github.com/go-xorm/xorm-redis-cache v0.0.0-20180727005610-859b313566b2
 	github.com/gordonklaus/ineffassign v0.0.0-20180909121442-1003c8bd00dc
 	github.com/imdario/mergo v0.3.6
+	github.com/jgautheron/goconst v0.0.0-20170703170152-9740945f5dcb
 	github.com/karalabe/xgo v0.0.0-20181007145344-72da7d1d3970
+	github.com/kisielk/gotool v1.0.0 // indirect
 	github.com/kr/pretty v0.1.0 // indirect
 	github.com/labstack/echo v3.3.5+incompatible
 	github.com/labstack/gommon v0.2.8
@@ -68,4 +69,5 @@ require (
 	gopkg.in/gomail.v2 v2.0.0-20160411212932-81ebce5c23df
 	gopkg.in/testfixtures.v2 v2.5.3
 	gopkg.in/yaml.v2 v2.2.2 // indirect
+	honnef.co/go/tools v0.0.0-20180920025451-e3ad64cb4ed3
 )

go.sum

@@ -18,7 +18,6 @@ github.com/beorn7/perks v0.0.0-20180321164747-3a771d992973/go.mod h1:Dwedo/Wpr24
 github.com/client9/misspell v0.3.4 h1:ta993UF76GwbvJcIo3Y68y/M3WxlpEHPWIGDkJYwzJI=
 github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=
 github.com/cweill/gotests v1.5.2 h1:kKqmKmS2wCV3tuLnfpbiuN8OlkosQZTpCfiqmiuNAsA=
-github.com/cweill/gotests v1.5.2/go.mod h1:XZYOJkGVkCRoymaIzmp9Wyi3rUgfA3oOnkuljYrjFV8=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/denisenkom/go-mssqldb v0.0.0-20181014144952-4e0d7dc8888f h1:WH0w/R4Yoey+04HhFxqZ6VX6I0d7RMyw5aXQ9UTvQPs=
@@ -68,10 +67,14 @@ github.com/hpcloud/tail v1.0.0 h1:nfCOvKYfkgYP8hkirhJocXT2+zOD8yUNjXaWfTlyFKI=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
 github.com/imdario/mergo v0.3.6 h1:xTNEAn+kxVO7dTZGu0CegyqKZmoWFI0rF8UxjlB2d28=
 github.com/imdario/mergo v0.3.6/go.mod h1:2EnlNZ0deacrJVfApfmtdGgDfMuh/nq6Ok1EcJh5FfA=
+github.com/jgautheron/goconst v0.0.0-20170703170152-9740945f5dcb h1:D5s1HIu80AcMGcqmk7fNIVptmAubVHHaj3v5Upex6Zs=
+github.com/jgautheron/goconst v0.0.0-20170703170152-9740945f5dcb/go.mod h1:82TxjOpWQiPmywlbIaB2ZkqJoSYJdLGPgAJDvM3PbKc=
 github.com/joho/godotenv v1.3.0 h1:Zjp+RcGpHhGlrMbJzXTrZZPrWj+1vfm90La1wgB6Bhc=
 github.com/joho/godotenv v1.3.0/go.mod h1:7hK45KPybAkOC6peb+G5yklZfMxEjkZhHbwpqxOKXbg=
 github.com/karalabe/xgo v0.0.0-20181007145344-72da7d1d3970 h1:0+1ZURVRim6FxA/jhWhJklsgoWc69q1sxlIu2Ztnhy0=
 github.com/karalabe/xgo v0.0.0-20181007145344-72da7d1d3970/go.mod h1:iYGcTYIPUvEWhFo6aKUuLchs+AV4ssYdyuBbQJZGcBk=
+github.com/kisielk/gotool v1.0.0 h1:AV2c/EiW3KqPNT9ZKl07ehoAGi4C5/01Cfbblndcapg=
+github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
 github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
@@ -141,10 +144,6 @@ github.com/swaggo/files v0.0.0-20180215091130-49c8a91ea3fa h1:194s4modF+3X3POBfG
 github.com/swaggo/files v0.0.0-20180215091130-49c8a91ea3fa/go.mod h1:gxQT6pBGRuIGunNf/+tSOB5OHvguWi8Tbt82WOkf35E=
 github.com/swaggo/gin-swagger v1.0.0 h1:k6Nn1jV49u+SNIWt7kejQS/iENZKZVMCNQrKOYatNF8=
 github.com/swaggo/gin-swagger v1.0.0/go.mod h1:Mt37wE46iUaTAOv+HSnHbJYssKGqbS25X19lNF4YpBo=
-github.com/swaggo/swag v1.4.0 h1:exX5ES4CdJWCCKmVPE+FAIN66cnHeMHU3i2SCMibBZc=
-github.com/swaggo/swag v1.4.0/go.mod h1:hog2WgeMOrQ/LvQ+o1YGTeT+vWVrbi0SiIslBtxKTyM=
-github.com/swaggo/swag v1.4.1-0.20181129020348-1c8533a91397 h1:xhlin3d0mSsxQlwxS+fHILT6PgG4Cmc2OZgzZL2bemI=
-github.com/swaggo/swag v1.4.1-0.20181129020348-1c8533a91397/go.mod h1:hog2WgeMOrQ/LvQ+o1YGTeT+vWVrbi0SiIslBtxKTyM=
 github.com/swaggo/swag v1.4.1-0.20181210033626-0e12fd5eb026 h1:XAOjF3QgjDUkVrPMO4rYvNptSHQgUlHwQsEdJOTxHQ8=
 github.com/swaggo/swag v1.4.1-0.20181210033626-0e12fd5eb026/go.mod h1:hog2WgeMOrQ/LvQ+o1YGTeT+vWVrbi0SiIslBtxKTyM=
 github.com/urfave/cli v1.20.0 h1:fDqGv3UG/4jbVl/QkFwEdddtEDjh/5Ov6X+0B/3bPaw=
@@ -202,3 +201,5 @@ gopkg.in/yaml.v2 v2.2.1 h1:mUhvW9EsL+naU5Q3cakzfE91YhliOondGd6ZrsDBHQE=
 gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+honnef.co/go/tools v0.0.0-20180920025451-e3ad64cb4ed3 h1:LyX67rVB0kBUFoROrQfzKwdrYLH1cRzHibxdJW85J1c=
+honnef.co/go/tools v0.0.0-20180920025451-e3ad64cb4ed3/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=

tools.go

@@ -29,4 +29,9 @@ import (
 	_ "github.com/swaggo/echo-swagger"
 	_ "github.com/swaggo/swag/cmd/swag"
 	_ "golang.org/x/lint/golint"
+
+	_ "github.com/jgautheron/goconst/cmd/goconst"
+	_ "honnef.co/go/tools/cmd/gosimple"
+	_ "honnef.co/go/tools/cmd/staticcheck"
+	_ "honnef.co/go/tools/cmd/unused"
 )

vendor/github.com/jgautheron/goconst/LICENSE

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2015 Jonathan Gautheron
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

vendor/github.com/jgautheron/goconst/README.md

@@ -0,0 +1,49 @@
+# goconst
+
+Find repeated strings that could be replaced by a constant.
+
+### Motivation
+
+There are obvious benefits to using constants instead of repeating strings, mostly to ease maintenance. Cannot argue against changing a single constant versus many strings.
+
+While this could be considered a beginner mistake, across time, multiple packages and large codebases, some repetition could have slipped in.
+
+### Get Started
+
+    $ go get github.com/jgautheron/goconst/cmd/goconst
+    $ goconst ./...
+
+### Usage
+
+```
+Usage:
+
+  goconst ARGS <directory>
+
+Flags:
+
+  -ignore            exclude files matching the given regular expression
+  -ignore-tests      exclude tests from the search (default: true)
+  -min-occurrences   report from how many occurrences (default: 2)
+  -min-length        only report strings with the minimum given length (default: 3)
+  -match-constant    look for existing constants matching the values
+  -numbers           search also for duplicated numbers
+  -min          	   minimum value, only works with -numbers
+  -max          	   maximum value, only works with -numbers
+  -output            output formatting (text or json)
+
+Examples:
+
+  goconst ./...
+  goconst -ignore "yacc|\.pb\." $GOPATH/src/github.com/cockroachdb/cockroach/...
+  goconst -min-occurrences 3 -output json $GOPATH/src/github.com/cockroachdb/cockroach
+  goconst -numbers -min 60 -max 512 .
+```
+
+### Other static analysis tools
+
+- [gogetimports](https://github.com/jgautheron/gogetimports): Get a JSON-formatted list of imports.
+- [usedexports](https://github.com/jgautheron/usedexports): Find exported variables that could be unexported.
+
+### License
+MIT

vendor/github.com/jgautheron/goconst/cmd/goconst/main.go

@@ -0,0 +1,166 @@
+package main
+
+import (
+	"encoding/json"
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"strconv"
+	"strings"
+
+	"github.com/jgautheron/goconst"
+)
+
+const usageDoc = `goconst: find repeated strings that could be replaced by a constant
+
+Usage:
+
+  goconst ARGS <directory> [<directory>...]
+
+Flags:
+
+  -ignore            exclude files matching the given regular expression
+  -ignore-tests      exclude tests from the search (default: true)
+  -min-occurrences   report from how many occurrences (default: 2)
+  -min-length        only report strings with the minimum given length (default: 3)
+  -match-constant    look for existing constants matching the strings
+  -numbers           search also for duplicated numbers
+  -min               minimum value, only works with -numbers
+  -max               maximum value, only works with -numbers
+  -output            output formatting (text or json)
+
+Examples:
+
+  goconst ./...
+  goconst -ignore "yacc|\.pb\." $GOPATH/src/github.com/cockroachdb/cockroach/...
+  goconst -min-occurrences 3 -output json $GOPATH/src/github.com/cockroachdb/cockroach
+  goconst -numbers -min 60 -max 512 .
+`
+
+var (
+	flagIgnore         = flag.String("ignore", "", "ignore files matching the given regular expression")
+	flagIgnoreTests    = flag.Bool("ignore-tests", true, "exclude tests from the search")
+	flagMinOccurrences = flag.Int("min-occurrences", 2, "report from how many occurrences")
+	flagMinLength      = flag.Int("min-length", 3, "only report strings with the minimum given length")
+	flagMatchConstant  = flag.Bool("match-constant", false, "look for existing constants matching the strings")
+	flagNumbers        = flag.Bool("numbers", false, "search also for duplicated numbers")
+	flagMin            = flag.Int("min", 0, "minimum value, only works with -numbers")
+	flagMax            = flag.Int("max", 0, "maximum value, only works with -numbers")
+	flagOutput         = flag.String("output", "text", "output formatting")
+)
+
+func main() {
+	flag.Usage = func() {
+		usage(os.Stderr)
+	}
+	flag.Parse()
+	log.SetPrefix("goconst: ")
+
+	args := flag.Args()
+	if len(args) < 1 {
+		usage(os.Stderr)
+		os.Exit(1)
+	}
+	for _, path := range args {
+		if err := run(path); err != nil {
+			log.Println(err)
+			os.Exit(1)
+		}
+	}
+}
+
+func run(path string) error {
+	gco := goconst.New(
+		path,
+		*flagIgnore,
+		*flagIgnoreTests,
+		*flagMatchConstant,
+		*flagNumbers,
+		*flagMinLength,
+	)
+	strs, consts, err := gco.ParseTree()
+	if err != nil {
+		return err
+	}
+
+	return printOutput(strs, consts, *flagOutput, *flagMinOccurrences, *flagMin, *flagMax)
+}
+
+func usage(out io.Writer) {
+	fmt.Fprintf(out, usageDoc)
+}
+
+func printOutput(strs goconst.Strings, consts goconst.Constants, output string, minOccurrences, min, max int) error {
+	for str, item := range strs {
+		// Filter out items whose occurrences don't match the min value
+		if len(item) < minOccurrences {
+			delete(strs, str)
+		}
+
+		// If the value is a number
+		if i, err := strconv.Atoi(str); err == nil {
+			if min != 0 && i < min {
+				delete(strs, str)
+			}
+			if max != 0 && i > max {
+				delete(strs, str)
+			}
+		}
+	}
+
+	switch output {
+	case "json":
+		enc := json.NewEncoder(os.Stdout)
+		err := enc.Encode(struct {
+			Strings   goconst.Strings   `json:"strings,omitEmpty"`
+			Constants goconst.Constants `json:"constants,omitEmpty"`
+		}{
+			strs, consts,
+		})
+		if err != nil {
+			return err
+		}
+	case "text":
+		for str, item := range strs {
+			for _, xpos := range item {
+				fmt.Printf(
+					`%s:%d:%d:%d other occurrence(s) of "%s" found in: %s`,
+					xpos.Filename,
+					xpos.Line,
+					xpos.Column,
+					len(item)-1,
+					str,
+					occurrences(item, xpos),
+				)
+				fmt.Print("\n")
+			}
+
+			if len(consts) == 0 {
+				continue
+			}
+			if cst, ok := consts[str]; ok {
+				// const should be in the same package and exported
+				fmt.Printf(`A matching constant has been found for "%s": %s`, str, cst.Name)
+				fmt.Printf("\n\t%s\n", cst.String())
+			}
+		}
+	default:
+		return fmt.Errorf(`Unsupported output format: %s`, output)
+	}
+	return nil
+}
+
+func occurrences(item []goconst.ExtendedPos, current goconst.ExtendedPos) string {
+	occurrences := []string{}
+	for _, xpos := range item {
+		if xpos == current {
+			continue
+		}
+		occurrences = append(occurrences, fmt.Sprintf(
+			"%s:%d:%d", xpos.Filename, xpos.Line, xpos.Column,
+		))
+	}
+	return strings.Join(occurrences, " ")
+}

vendor/github.com/jgautheron/goconst/parser.go

@@ -0,0 +1,136 @@
+// Package goconst finds repeated strings that could be replaced by a constant.
+//
+// There are obvious benefits to using constants instead of repeating strings,
+// mostly to ease maintenance. Cannot argue against changing a single constant versus many strings.
+// While this could be considered a beginner mistake, across time,
+// multiple packages and large codebases, some repetition could have slipped in.
+package goconst
+
+import (
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"log"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+)
+
+const (
+	testSuffix = "_test.go"
+)
+
+type Parser struct {
+	// Meant to be passed via New()
+	path, ignore               string
+	ignoreTests, matchConstant bool
+	minLength                  int
+
+	supportedTokens []token.Token
+
+	// Internals
+	strs   Strings
+	consts Constants
+}
+
+// New creates a new instance of the parser.
+// This is your entry point if you'd like to use goconst as an API.
+func New(path, ignore string, ignoreTests, matchConstant, numbers bool, minLength int) *Parser {
+	supportedTokens := []token.Token{token.STRING}
+	if numbers {
+		supportedTokens = append(supportedTokens, token.INT, token.FLOAT)
+	}
+
+	return &Parser{
+		path:            path,
+		ignore:          ignore,
+		ignoreTests:     ignoreTests,
+		matchConstant:   matchConstant,
+		minLength:       minLength,
+		supportedTokens: supportedTokens,
+
+		// Initialize the maps
+		strs:   Strings{},
+		consts: Constants{},
+	}
+}
+
+// ParseTree will search the given path for occurrences that could be moved into constants.
+// If "..." is appended, the search will be recursive.
+func (p *Parser) ParseTree() (Strings, Constants, error) {
+	pathLen := len(p.path)
+	// Parse recursively the given path if the recursive notation is found
+	if pathLen >= 5 && p.path[pathLen-3:] == "..." {
+		filepath.Walk(p.path[:pathLen-3], func(path string, f os.FileInfo, err error) error {
+			if err != nil {
+				log.Println(err)
+				// resume walking
+				return nil
+			}
+
+			if f.IsDir() {
+				p.parseDir(path)
+			}
+			return nil
+		})
+	} else {
+		p.parseDir(p.path)
+	}
+	return p.strs, p.consts, nil
+}
+
+func (p *Parser) parseDir(dir string) error {
+	fset := token.NewFileSet()
+	pkgs, err := parser.ParseDir(fset, dir, func(info os.FileInfo) bool {
+		valid, name := true, info.Name()
+
+		if p.ignoreTests {
+			if strings.HasSuffix(name, testSuffix) {
+				valid = false
+			}
+		}
+
+		if len(p.ignore) != 0 {
+			match, err := regexp.MatchString(p.ignore, dir+name)
+			if err != nil {
+				log.Fatal(err)
+				return true
+			}
+			if match {
+				valid = false
+			}
+		}
+
+		return valid
+	}, 0)
+	if err != nil {
+		return err
+	}
+
+	for _, pkg := range pkgs {
+		for fn, f := range pkg.Files {
+			ast.Walk(&treeVisitor{
+				fileSet:     fset,
+				packageName: pkg.Name,
+				fileName:    fn,
+				p:           p,
+			}, f)
+		}
+	}
+
+	return nil
+}
+
+type Strings map[string][]ExtendedPos
+type Constants map[string]ConstType
+
+type ConstType struct {
+	token.Position
+	Name, packageName string
+}
+
+type ExtendedPos struct {
+	token.Position
+	packageName string
+}

vendor/github.com/jgautheron/goconst/visitor.go

@@ -0,0 +1,143 @@
+package goconst
+
+import (
+	"go/ast"
+	"go/token"
+	"strings"
+)
+
+// treeVisitor carries the package name and file name
+// for passing it to the imports map, and the fileSet for
+// retrieving the token.Position.
+type treeVisitor struct {
+	p                     *Parser
+	fileSet               *token.FileSet
+	packageName, fileName string
+}
+
+// Visit browses the AST tree for strings that could be potentially
+// replaced by constants.
+// A map of existing constants is built as well (-match-constant).
+func (v *treeVisitor) Visit(node ast.Node) ast.Visitor {
+	if node == nil {
+		return v
+	}
+
+	// A single case with "ast.BasicLit" would be much easier
+	// but then we wouldn't be able to tell in which context
+	// the string is defined (could be a constant definition).
+	switch t := node.(type) {
+	// Scan for constants in an attempt to match strings with existing constants
+	case *ast.GenDecl:
+		if !v.p.matchConstant {
+			return v
+		}
+		if t.Tok != token.CONST {
+			return v
+		}
+
+		for _, spec := range t.Specs {
+			val := spec.(*ast.ValueSpec)
+			for i, str := range val.Values {
+				lit, ok := str.(*ast.BasicLit)
+				if !ok || !v.isSupported(lit.Kind) {
+					continue
+				}
+
+				v.addConst(val.Names[i].Name, lit.Value, val.Names[i].Pos())
+			}
+		}
+
+	// foo := "moo"
+	case *ast.AssignStmt:
+		for _, rhs := range t.Rhs {
+			lit, ok := rhs.(*ast.BasicLit)
+			if !ok || !v.isSupported(lit.Kind) {
+				continue
+			}
+
+			v.addString(lit.Value, rhs.(*ast.BasicLit).Pos())
+		}
+
+	// if foo == "moo"
+	case *ast.BinaryExpr:
+		if t.Op != token.EQL && t.Op != token.NEQ {
+			return v
+		}
+
+		var lit *ast.BasicLit
+		var ok bool
+
+		lit, ok = t.X.(*ast.BasicLit)
+		if ok && v.isSupported(lit.Kind) {
+			v.addString(lit.Value, lit.Pos())
+		}
+
+		lit, ok = t.Y.(*ast.BasicLit)
+		if ok && v.isSupported(lit.Kind) {
+			v.addString(lit.Value, lit.Pos())
+		}
+
+	// case "foo":
+	case *ast.CaseClause:
+		for _, item := range t.List {
+			lit, ok := item.(*ast.BasicLit)
+			if ok && v.isSupported(lit.Kind) {
+				v.addString(lit.Value, lit.Pos())
+			}
+		}
+
+	// return "boo"
+	case *ast.ReturnStmt:
+		for _, item := range t.Results {
+			lit, ok := item.(*ast.BasicLit)
+			if ok && v.isSupported(lit.Kind) {
+				v.addString(lit.Value, lit.Pos())
+			}
+		}
+	}
+
+	return v
+}
+
+// addString adds a string in the map along with its position in the tree.
+func (v *treeVisitor) addString(str string, pos token.Pos) {
+	str = strings.Replace(str, `"`, "", 2)
+
+	// Ignore empty strings
+	if len(str) == 0 {
+		return
+	}
+
+	if len(str) < v.p.minLength {
+		return
+	}
+
+	_, ok := v.p.strs[str]
+	if !ok {
+		v.p.strs[str] = make([]ExtendedPos, 0)
+	}
+	v.p.strs[str] = append(v.p.strs[str], ExtendedPos{
+		packageName: v.packageName,
+		Position:    v.fileSet.Position(pos),
+	})
+}
+
+// addConst adds a const in the map along with its position in the tree.
+func (v *treeVisitor) addConst(name string, val string, pos token.Pos) {
+	val = strings.Replace(val, `"`, "", 2)
+	v.p.consts[val] = ConstType{
+		Name:        name,
+		packageName: v.packageName,
+		Position:    v.fileSet.Position(pos),
+	}
+}
+
+func (v *treeVisitor) isSupported(tk token.Token) bool {
+	for _, s := range v.p.supportedTokens {
+		if tk == s {
+			return true
+		}
+	}
+	return false
+}

vendor/github.com/kisielk/gotool/.travis.yml

@@ -0,0 +1,23 @@
+sudo: false
+language: go
+go:
+  - 1.2
+  - 1.3
+  - 1.4
+  - 1.5
+  - 1.6
+  - 1.7
+  - 1.8
+  - 1.9
+  - master
+matrix:
+  allow_failures:
+    - go: master
+  fast_finish: true
+install:
+  - # Skip.
+script:
+  - go get -t -v ./...
+  - diff -u <(echo -n) <(gofmt -d .)
+  - go tool vet .
+  - go test -v -race ./...

vendor/github.com/kisielk/gotool/LEGAL

@@ -0,0 +1,32 @@
+All the files in this distribution are covered under either the MIT
+license (see the file LICENSE) except some files mentioned below.
+
+match.go, match_test.go:
+
+    Copyright (c) 2009 The Go Authors. All rights reserved.
+
+    Redistribution and use in source and binary forms, with or without
+    modification, are permitted provided that the following conditions are
+    met:
+
+       * Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+       * Redistributions in binary form must reproduce the above
+    copyright notice, this list of conditions and the following disclaimer
+    in the documentation and/or other materials provided with the
+    distribution.
+       * Neither the name of Google Inc. nor the names of its
+    contributors may be used to endorse or promote products derived from
+    this software without specific prior written permission.
+
+    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+    A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+    OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+    SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+    LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+    OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/github.com/kisielk/gotool/LICENSE

@@ -0,0 +1,20 @@
+Copyright (c) 2013 Kamil Kisiel <kamil@kamilkisiel.net>
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

vendor/github.com/kisielk/gotool/README.md

@@ -0,0 +1,6 @@
+gotool
+======
+[![GoDoc](https://godoc.org/github.com/kisielk/gotool?status.svg)](https://godoc.org/github.com/kisielk/gotool)
+[![Build Status](https://travis-ci.org/kisielk/gotool.svg?branch=master)](https://travis-ci.org/kisielk/gotool)
+
+Package gotool contains utility functions used to implement the standard "cmd/go" tool, provided as a convenience to developers who want to write tools with similar semantics.

vendor/github.com/kisielk/gotool/go.mod

@@ -0,0 +1 @@
+module "github.com/kisielk/gotool"

vendor/github.com/kisielk/gotool/go13.go

@@ -0,0 +1,15 @@
+// +build !go1.4
+
+package gotool
+
+import (
+	"go/build"
+	"path/filepath"
+	"runtime"
+)
+
+var gorootSrc = filepath.Join(runtime.GOROOT(), "src", "pkg")
+
+func shouldIgnoreImport(p *build.Package) bool {
+	return true
+}

vendor/github.com/kisielk/gotool/go14-15.go

@@ -0,0 +1,15 @@
+// +build go1.4,!go1.6
+
+package gotool
+
+import (
+	"go/build"
+	"path/filepath"
+	"runtime"
+)
+
+var gorootSrc = filepath.Join(runtime.GOROOT(), "src")
+
+func shouldIgnoreImport(p *build.Package) bool {
+	return true
+}

vendor/github.com/kisielk/gotool/go16-18.go

@@ -0,0 +1,15 @@
+// +build go1.6,!go1.9
+
+package gotool
+
+import (
+	"go/build"
+	"path/filepath"
+	"runtime"
+)
+
+var gorootSrc = filepath.Join(runtime.GOROOT(), "src")
+
+func shouldIgnoreImport(p *build.Package) bool {
+	return p == nil || len(p.InvalidGoFiles) == 0
+}

vendor/github.com/kisielk/gotool/internal/load/path.go

@@ -0,0 +1,27 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build go1.9
+
+package load
+
+import (
+	"strings"
+)
+
+// hasPathPrefix reports whether the path s begins with the
+// elements in prefix.
+func hasPathPrefix(s, prefix string) bool {
+	switch {
+	default:
+		return false
+	case len(s) == len(prefix):
+		return s == prefix
+	case len(s) > len(prefix):
+		if prefix != "" && prefix[len(prefix)-1] == '/' {
+			return strings.HasPrefix(s, prefix)
+		}
+		return s[len(prefix)] == '/' && s[:len(prefix)] == prefix
+	}
+}

vendor/github.com/kisielk/gotool/internal/load/pkg.go

@@ -0,0 +1,25 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build go1.9
+
+// Package load loads packages.
+package load
+
+import (
+	"strings"
+)
+
+// isStandardImportPath reports whether $GOROOT/src/path should be considered
+// part of the standard distribution. For historical reasons we allow people to add
+// their own code to $GOROOT instead of using $GOPATH, but we assume that
+// code will start with a domain name (dot in the first element).
+func isStandardImportPath(path string) bool {
+	i := strings.Index(path, "/")
+	if i < 0 {
+		i = len(path)
+	}
+	elem := path[:i]
+	return !strings.Contains(elem, ".")
+}

vendor/github.com/kisielk/gotool/internal/load/search.go

@@ -0,0 +1,354 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build go1.9
+
+package load
+
+import (
+	"fmt"
+	"go/build"
+	"log"
+	"os"
+	"path"
+	"path/filepath"
+	"regexp"
+	"strings"
+)
+
+// Context specifies values for operation of ImportPaths that would
+// otherwise come from cmd/go/internal/cfg package.
+//
+// This is a construct added for gotool purposes and doesn't have
+// an equivalent upstream in cmd/go.
+type Context struct {
+	// BuildContext is the build context to use.
+	BuildContext build.Context
+
+	// GOROOTsrc is the location of the src directory in GOROOT.
+	// At this time, it's used only in MatchPackages to skip
+	// GOOROOT/src entry from BuildContext.SrcDirs output.
+	GOROOTsrc string
+}
+
+// allPackages returns all the packages that can be found
+// under the $GOPATH directories and $GOROOT matching pattern.
+// The pattern is either "all" (all packages), "std" (standard packages),
+// "cmd" (standard commands), or a path including "...".
+func (c *Context) allPackages(pattern string) []string {
+	pkgs := c.MatchPackages(pattern)
+	if len(pkgs) == 0 {
+		fmt.Fprintf(os.Stderr, "warning: %q matched no packages\n", pattern)
+	}
+	return pkgs
+}
+
+// allPackagesInFS is like allPackages but is passed a pattern
+// beginning ./ or ../, meaning it should scan the tree rooted
+// at the given directory. There are ... in the pattern too.
+func (c *Context) allPackagesInFS(pattern string) []string {
+	pkgs := c.MatchPackagesInFS(pattern)
+	if len(pkgs) == 0 {
+		fmt.Fprintf(os.Stderr, "warning: %q matched no packages\n", pattern)
+	}
+	return pkgs
+}
+
+// MatchPackages returns a list of package paths matching pattern
+// (see go help packages for pattern syntax).
+func (c *Context) MatchPackages(pattern string) []string {
+	match := func(string) bool { return true }
+	treeCanMatch := func(string) bool { return true }
+	if !IsMetaPackage(pattern) {
+		match = matchPattern(pattern)
+		treeCanMatch = treeCanMatchPattern(pattern)
+	}
+
+	have := map[string]bool{
+		"builtin": true, // ignore pseudo-package that exists only for documentation
+	}
+	if !c.BuildContext.CgoEnabled {
+		have["runtime/cgo"] = true // ignore during walk
+	}
+	var pkgs []string
+
+	for _, src := range c.BuildContext.SrcDirs() {
+		if (pattern == "std" || pattern == "cmd") && src != c.GOROOTsrc {
+			continue
+		}
+		src = filepath.Clean(src) + string(filepath.Separator)
+		root := src
+		if pattern == "cmd" {
+			root += "cmd" + string(filepath.Separator)
+		}
+		filepath.Walk(root, func(path string, fi os.FileInfo, err error) error {
+			if err != nil || path == src {
+				return nil
+			}
+
+			want := true
+			// Avoid .foo, _foo, and testdata directory trees.
+			_, elem := filepath.Split(path)
+			if strings.HasPrefix(elem, ".") || strings.HasPrefix(elem, "_") || elem == "testdata" {
+				want = false
+			}
+
+			name := filepath.ToSlash(path[len(src):])
+			if pattern == "std" && (!isStandardImportPath(name) || name == "cmd") {
+				// The name "std" is only the standard library.
+				// If the name is cmd, it's the root of the command tree.
+				want = false
+			}
+			if !treeCanMatch(name) {
+				want = false
+			}
+
+			if !fi.IsDir() {
+				if fi.Mode()&os.ModeSymlink != 0 && want {
+					if target, err := os.Stat(path); err == nil && target.IsDir() {
+						fmt.Fprintf(os.Stderr, "warning: ignoring symlink %s\n", path)
+					}
+				}
+				return nil
+			}
+			if !want {
+				return filepath.SkipDir
+			}
+
+			if have[name] {
+				return nil
+			}
+			have[name] = true
+			if !match(name) {
+				return nil
+			}
+			pkg, err := c.BuildContext.ImportDir(path, 0)
+			if err != nil {
+				if _, noGo := err.(*build.NoGoError); noGo {
+					return nil
+				}
+			}
+
+			// If we are expanding "cmd", skip main
+			// packages under cmd/vendor. At least as of
+			// March, 2017, there is one there for the
+			// vendored pprof tool.
+			if pattern == "cmd" && strings.HasPrefix(pkg.ImportPath, "cmd/vendor") && pkg.Name == "main" {
+				return nil
+			}
+
+			pkgs = append(pkgs, name)
+			return nil
+		})
+	}
+	return pkgs
+}
+
+// MatchPackagesInFS returns a list of package paths matching pattern,
+// which must begin with ./ or ../
+// (see go help packages for pattern syntax).
+func (c *Context) MatchPackagesInFS(pattern string) []string {
+	// Find directory to begin the scan.
+	// Could be smarter but this one optimization
+	// is enough for now, since ... is usually at the
+	// end of a path.
+	i := strings.Index(pattern, "...")
+	dir, _ := path.Split(pattern[:i])
+
+	// pattern begins with ./ or ../.
+	// path.Clean will discard the ./ but not the ../.
+	// We need to preserve the ./ for pattern matching
+	// and in the returned import paths.
+	prefix := ""
+	if strings.HasPrefix(pattern, "./") {
+		prefix = "./"
+	}
+	match := matchPattern(pattern)
+
+	var pkgs []string
+	filepath.Walk(dir, func(path string, fi os.FileInfo, err error) error {
+		if err != nil || !fi.IsDir() {
+			return nil
+		}
+		if path == dir {
+			// filepath.Walk starts at dir and recurses. For the recursive case,
+			// the path is the result of filepath.Join, which calls filepath.Clean.
+			// The initial case is not Cleaned, though, so we do this explicitly.
+			//
+			// This converts a path like "./io/" to "io". Without this step, running
+			// "cd $GOROOT/src; go list ./io/..." would incorrectly skip the io
+			// package, because prepending the prefix "./" to the unclean path would
+			// result in "././io", and match("././io") returns false.
+			path = filepath.Clean(path)
+		}
+
+		// Avoid .foo, _foo, and testdata directory trees, but do not avoid "." or "..".
+		_, elem := filepath.Split(path)
+		dot := strings.HasPrefix(elem, ".") && elem != "." && elem != ".."
+		if dot || strings.HasPrefix(elem, "_") || elem == "testdata" {
+			return filepath.SkipDir
+		}
+
+		name := prefix + filepath.ToSlash(path)
+		if !match(name) {
+			return nil
+		}
+
+		// We keep the directory if we can import it, or if we can't import it
+		// due to invalid Go source files. This means that directories containing
+		// parse errors will be built (and fail) instead of being silently skipped
+		// as not matching the pattern. Go 1.5 and earlier skipped, but that
+		// behavior means people miss serious mistakes.
+		// See golang.org/issue/11407.
+		if p, err := c.BuildContext.ImportDir(path, 0); err != nil && (p == nil || len(p.InvalidGoFiles) == 0) {
+			if _, noGo := err.(*build.NoGoError); !noGo {
+				log.Print(err)
+			}
+			return nil
+		}
+		pkgs = append(pkgs, name)
+		return nil
+	})
+	return pkgs
+}
+
+// treeCanMatchPattern(pattern)(name) reports whether
+// name or children of name can possibly match pattern.
+// Pattern is the same limited glob accepted by matchPattern.
+func treeCanMatchPattern(pattern string) func(name string) bool {
+	wildCard := false
+	if i := strings.Index(pattern, "..."); i >= 0 {
+		wildCard = true
+		pattern = pattern[:i]
+	}
+	return func(name string) bool {
+		return len(name) <= len(pattern) && hasPathPrefix(pattern, name) ||
+			wildCard && strings.HasPrefix(name, pattern)
+	}
+}
+
+// matchPattern(pattern)(name) reports whether
+// name matches pattern. Pattern is a limited glob
+// pattern in which '...' means 'any string' and there
+// is no other special syntax.
+// Unfortunately, there are two special cases. Quoting "go help packages":
+//
+// First, /... at the end of the pattern can match an empty string,
+// so that net/... matches both net and packages in its subdirectories, like net/http.
+// Second, any slash-separted pattern element containing a wildcard never
+// participates in a match of the "vendor" element in the path of a vendored
+// package, so that ./... does not match packages in subdirectories of
+// ./vendor or ./mycode/vendor, but ./vendor/... and ./mycode/vendor/... do.
+// Note, however, that a directory named vendor that itself contains code
+// is not a vendored package: cmd/vendor would be a command named vendor,
+// and the pattern cmd/... matches it.
+func matchPattern(pattern string) func(name string) bool {
+	// Convert pattern to regular expression.
+	// The strategy for the trailing /... is to nest it in an explicit ? expression.
+	// The strategy for the vendor exclusion is to change the unmatchable
+	// vendor strings to a disallowed code point (vendorChar) and to use
+	// "(anything but that codepoint)*" as the implementation of the ... wildcard.
+	// This is a bit complicated but the obvious alternative,
+	// namely a hand-written search like in most shell glob matchers,
+	// is too easy to make accidentally exponential.
+	// Using package regexp guarantees linear-time matching.
+
+	const vendorChar = "\x00"
+
+	if strings.Contains(pattern, vendorChar) {
+		return func(name string) bool { return false }
+	}
+
+	re := regexp.QuoteMeta(pattern)
+	re = replaceVendor(re, vendorChar)
+	switch {
+	case strings.HasSuffix(re, `/`+vendorChar+`/\.\.\.`):
+		re = strings.TrimSuffix(re, `/`+vendorChar+`/\.\.\.`) + `(/vendor|/` + vendorChar + `/\.\.\.)`
+	case re == vendorChar+`/\.\.\.`:
+		re = `(/vendor|/` + vendorChar + `/\.\.\.)`
+	case strings.HasSuffix(re, `/\.\.\.`):
+		re = strings.TrimSuffix(re, `/\.\.\.`) + `(/\.\.\.)?`
+	}
+	re = strings.Replace(re, `\.\.\.`, `[^`+vendorChar+`]*`, -1)
+
+	reg := regexp.MustCompile(`^` + re + `$`)
+
+	return func(name string) bool {
+		if strings.Contains(name, vendorChar) {
+			return false
+		}
+		return reg.MatchString(replaceVendor(name, vendorChar))
+	}
+}
+
+// replaceVendor returns the result of replacing
+// non-trailing vendor path elements in x with repl.
+func replaceVendor(x, repl string) string {
+	if !strings.Contains(x, "vendor") {
+		return x
+	}
+	elem := strings.Split(x, "/")
+	for i := 0; i < len(elem)-1; i++ {
+		if elem[i] == "vendor" {
+			elem[i] = repl
+		}
+	}
+	return strings.Join(elem, "/")
+}
+
+// ImportPaths returns the import paths to use for the given command line.
+func (c *Context) ImportPaths(args []string) []string {
+	args = c.ImportPathsNoDotExpansion(args)
+	var out []string
+	for _, a := range args {
+		if strings.Contains(a, "...") {
+			if build.IsLocalImport(a) {
+				out = append(out, c.allPackagesInFS(a)...)
+			} else {
+				out = append(out, c.allPackages(a)...)
+			}
+			continue
+		}
+		out = append(out, a)
+	}
+	return out
+}
+
+// ImportPathsNoDotExpansion returns the import paths to use for the given
+// command line, but it does no ... expansion.
+func (c *Context) ImportPathsNoDotExpansion(args []string) []string {
+	if len(args) == 0 {
+		return []string{"."}
+	}
+	var out []string
+	for _, a := range args {
+		// Arguments are supposed to be import paths, but
+		// as a courtesy to Windows developers, rewrite \ to /
+		// in command-line arguments. Handles .\... and so on.
+		if filepath.Separator == '\\' {
+			a = strings.Replace(a, `\`, `/`, -1)
+		}
+
+		// Put argument in canonical form, but preserve leading ./.
+		if strings.HasPrefix(a, "./") {
+			a = "./" + path.Clean(a)
+			if a == "./." {
+				a = "."
+			}
+		} else {
+			a = path.Clean(a)
+		}
+		if IsMetaPackage(a) {
+			out = append(out, c.allPackages(a)...)
+			continue
+		}
+		out = append(out, a)
+	}
+	return out
+}
+
+// IsMetaPackage checks if name is a reserved package name that expands to multiple packages.
+func IsMetaPackage(name string) bool {
+	return name == "std" || name == "cmd" || name == "all"
+}

vendor/github.com/kisielk/gotool/match.go

@@ -0,0 +1,56 @@
+// Copyright (c) 2009 The Go Authors. All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//    * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//    * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//    * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// +build go1.9
+
+package gotool
+
+import (
+	"path/filepath"
+
+	"github.com/kisielk/gotool/internal/load"
+)
+
+// importPaths returns the import paths to use for the given command line.
+func (c *Context) importPaths(args []string) []string {
+	lctx := load.Context{
+		BuildContext: c.BuildContext,
+		GOROOTsrc:    c.joinPath(c.BuildContext.GOROOT, "src"),
+	}
+	return lctx.ImportPaths(args)
+}
+
+// joinPath calls c.BuildContext.JoinPath (if not nil) or else filepath.Join.
+//
+// It's a copy of the unexported build.Context.joinPath helper.
+func (c *Context) joinPath(elem ...string) string {
+	if f := c.BuildContext.JoinPath; f != nil {
+		return f(elem...)
+	}
+	return filepath.Join(elem...)
+}

vendor/github.com/kisielk/gotool/match18.go

@@ -0,0 +1,317 @@
+// Copyright (c) 2009 The Go Authors. All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//    * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//    * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//    * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// +build !go1.9
+
+package gotool
+
+import (
+	"fmt"
+	"go/build"
+	"log"
+	"os"
+	"path"
+	"path/filepath"
+	"regexp"
+	"strings"
+)
+
+// This file contains code from the Go distribution.
+
+// matchPattern(pattern)(name) reports whether
+// name matches pattern. Pattern is a limited glob
+// pattern in which '...' means 'any string' and there
+// is no other special syntax.
+func matchPattern(pattern string) func(name string) bool {
+	re := regexp.QuoteMeta(pattern)
+	re = strings.Replace(re, `\.\.\.`, `.*`, -1)
+	// Special case: foo/... matches foo too.
+	if strings.HasSuffix(re, `/.*`) {
+		re = re[:len(re)-len(`/.*`)] + `(/.*)?`
+	}
+	reg := regexp.MustCompile(`^` + re + `$`)
+	return reg.MatchString
+}
+
+// matchPackages returns a list of package paths matching pattern
+// (see go help packages for pattern syntax).
+func (c *Context) matchPackages(pattern string) []string {
+	match := func(string) bool { return true }
+	treeCanMatch := func(string) bool { return true }
+	if !isMetaPackage(pattern) {
+		match = matchPattern(pattern)
+		treeCanMatch = treeCanMatchPattern(pattern)
+	}
+
+	have := map[string]bool{
+		"builtin": true, // ignore pseudo-package that exists only for documentation
+	}
+	if !c.BuildContext.CgoEnabled {
+		have["runtime/cgo"] = true // ignore during walk
+	}
+	var pkgs []string
+
+	for _, src := range c.BuildContext.SrcDirs() {
+		if (pattern == "std" || pattern == "cmd") && src != gorootSrc {
+			continue
+		}
+		src = filepath.Clean(src) + string(filepath.Separator)
+		root := src
+		if pattern == "cmd" {
+			root += "cmd" + string(filepath.Separator)
+		}
+		filepath.Walk(root, func(path string, fi os.FileInfo, err error) error {
+			if err != nil || !fi.IsDir() || path == src {
+				return nil
+			}
+
+			// Avoid .foo, _foo, and testdata directory trees.
+			_, elem := filepath.Split(path)
+			if strings.HasPrefix(elem, ".") || strings.HasPrefix(elem, "_") || elem == "testdata" {
+				return filepath.SkipDir
+			}
+
+			name := filepath.ToSlash(path[len(src):])
+			if pattern == "std" && (!isStandardImportPath(name) || name == "cmd") {
+				// The name "std" is only the standard library.
+				// If the name is cmd, it's the root of the command tree.
+				return filepath.SkipDir
+			}
+			if !treeCanMatch(name) {
+				return filepath.SkipDir
+			}
+			if have[name] {
+				return nil
+			}
+			have[name] = true
+			if !match(name) {
+				return nil
+			}
+			_, err = c.BuildContext.ImportDir(path, 0)
+			if err != nil {
+				if _, noGo := err.(*build.NoGoError); noGo {
+					return nil
+				}
+			}
+			pkgs = append(pkgs, name)
+			return nil
+		})
+	}
+	return pkgs
+}
+
+// importPathsNoDotExpansion returns the import paths to use for the given
+// command line, but it does no ... expansion.
+func (c *Context) importPathsNoDotExpansion(args []string) []string {
+	if len(args) == 0 {
+		return []string{"."}
+	}
+	var out []string
+	for _, a := range args {
+		// Arguments are supposed to be import paths, but
+		// as a courtesy to Windows developers, rewrite \ to /
+		// in command-line arguments. Handles .\... and so on.
+		if filepath.Separator == '\\' {
+			a = strings.Replace(a, `\`, `/`, -1)
+		}
+
+		// Put argument in canonical form, but preserve leading ./.
+		if strings.HasPrefix(a, "./") {
+			a = "./" + path.Clean(a)
+			if a == "./." {
+				a = "."
+			}
+		} else {
+			a = path.Clean(a)
+		}
+		if isMetaPackage(a) {
+			out = append(out, c.allPackages(a)...)
+			continue
+		}
+		out = append(out, a)
+	}
+	return out
+}
+
+// importPaths returns the import paths to use for the given command line.
+func (c *Context) importPaths(args []string) []string {
+	args = c.importPathsNoDotExpansion(args)
+	var out []string
+	for _, a := range args {
+		if strings.Contains(a, "...") {
+			if build.IsLocalImport(a) {
+				out = append(out, c.allPackagesInFS(a)...)
+			} else {
+				out = append(out, c.allPackages(a)...)
+			}
+			continue
+		}
+		out = append(out, a)
+	}
+	return out
+}
+
+// allPackages returns all the packages that can be found
+// under the $GOPATH directories and $GOROOT matching pattern.
+// The pattern is either "all" (all packages), "std" (standard packages),
+// "cmd" (standard commands), or a path including "...".
+func (c *Context) allPackages(pattern string) []string {
+	pkgs := c.matchPackages(pattern)
+	if len(pkgs) == 0 {
+		fmt.Fprintf(os.Stderr, "warning: %q matched no packages\n", pattern)
+	}
+	return pkgs
+}
+
+// allPackagesInFS is like allPackages but is passed a pattern
+// beginning ./ or ../, meaning it should scan the tree rooted
+// at the given directory. There are ... in the pattern too.
+func (c *Context) allPackagesInFS(pattern string) []string {
+	pkgs := c.matchPackagesInFS(pattern)
+	if len(pkgs) == 0 {
+		fmt.Fprintf(os.Stderr, "warning: %q matched no packages\n", pattern)
+	}
+	return pkgs
+}
+
+// matchPackagesInFS returns a list of package paths matching pattern,
+// which must begin with ./ or ../
+// (see go help packages for pattern syntax).
+func (c *Context) matchPackagesInFS(pattern string) []string {
+	// Find directory to begin the scan.
+	// Could be smarter but this one optimization
+	// is enough for now, since ... is usually at the
+	// end of a path.
+	i := strings.Index(pattern, "...")
+	dir, _ := path.Split(pattern[:i])
+
+	// pattern begins with ./ or ../.
+	// path.Clean will discard the ./ but not the ../.
+	// We need to preserve the ./ for pattern matching
+	// and in the returned import paths.
+	prefix := ""
+	if strings.HasPrefix(pattern, "./") {
+		prefix = "./"
+	}
+	match := matchPattern(pattern)
+
+	var pkgs []string
+	filepath.Walk(dir, func(path string, fi os.FileInfo, err error) error {
+		if err != nil || !fi.IsDir() {
+			return nil
+		}
+		if path == dir {
+			// filepath.Walk starts at dir and recurses. For the recursive case,
+			// the path is the result of filepath.Join, which calls filepath.Clean.
+			// The initial case is not Cleaned, though, so we do this explicitly.
+			//
+			// This converts a path like "./io/" to "io". Without this step, running
+			// "cd $GOROOT/src; go list ./io/..." would incorrectly skip the io
+			// package, because prepending the prefix "./" to the unclean path would
+			// result in "././io", and match("././io") returns false.
+			path = filepath.Clean(path)
+		}
+
+		// Avoid .foo, _foo, and testdata directory trees, but do not avoid "." or "..".
+		_, elem := filepath.Split(path)
+		dot := strings.HasPrefix(elem, ".") && elem != "." && elem != ".."
+		if dot || strings.HasPrefix(elem, "_") || elem == "testdata" {
+			return filepath.SkipDir
+		}
+
+		name := prefix + filepath.ToSlash(path)
+		if !match(name) {
+			return nil
+		}
+
+		// We keep the directory if we can import it, or if we can't import it
+		// due to invalid Go source files. This means that directories containing
+		// parse errors will be built (and fail) instead of being silently skipped
+		// as not matching the pattern. Go 1.5 and earlier skipped, but that
+		// behavior means people miss serious mistakes.
+		// See golang.org/issue/11407.
+		if p, err := c.BuildContext.ImportDir(path, 0); err != nil && shouldIgnoreImport(p) {
+			if _, noGo := err.(*build.NoGoError); !noGo {
+				log.Print(err)
+			}
+			return nil
+		}
+		pkgs = append(pkgs, name)
+		return nil
+	})
+	return pkgs
+}
+
+// isMetaPackage checks if name is a reserved package name that expands to multiple packages.
+func isMetaPackage(name string) bool {
+	return name == "std" || name == "cmd" || name == "all"
+}
+
+// isStandardImportPath reports whether $GOROOT/src/path should be considered
+// part of the standard distribution. For historical reasons we allow people to add
+// their own code to $GOROOT instead of using $GOPATH, but we assume that
+// code will start with a domain name (dot in the first element).
+func isStandardImportPath(path string) bool {
+	i := strings.Index(path, "/")
+	if i < 0 {
+		i = len(path)
+	}
+	elem := path[:i]
+	return !strings.Contains(elem, ".")
+}
+
+// hasPathPrefix reports whether the path s begins with the
+// elements in prefix.
+func hasPathPrefix(s, prefix string) bool {
+	switch {
+	default:
+		return false
+	case len(s) == len(prefix):
+		return s == prefix
+	case len(s) > len(prefix):
+		if prefix != "" && prefix[len(prefix)-1] == '/' {
+			return strings.HasPrefix(s, prefix)
+		}
+		return s[len(prefix)] == '/' && s[:len(prefix)] == prefix
+	}
+}
+
+// treeCanMatchPattern(pattern)(name) reports whether
+// name or children of name can possibly match pattern.
+// Pattern is the same limited glob accepted by matchPattern.
+func treeCanMatchPattern(pattern string) func(name string) bool {
+	wildCard := false
+	if i := strings.Index(pattern, "..."); i >= 0 {
+		wildCard = true
+		pattern = pattern[:i]
+	}
+	return func(name string) bool {
+		return len(name) <= len(pattern) && hasPathPrefix(pattern, name) ||
+			wildCard && strings.HasPrefix(name, pattern)
+	}
+}

vendor/github.com/kisielk/gotool/tool.go

@@ -0,0 +1,48 @@
+// Package gotool contains utility functions used to implement the standard
+// "cmd/go" tool, provided as a convenience to developers who want to write
+// tools with similar semantics.
+package gotool
+
+import "go/build"
+
+// Export functions here to make it easier to keep the implementations up to date with upstream.
+
+// DefaultContext is the default context that uses build.Default.
+var DefaultContext = Context{
+	BuildContext: build.Default,
+}
+
+// A Context specifies the supporting context.
+type Context struct {
+	// BuildContext is the build.Context that is used when computing import paths.
+	BuildContext build.Context
+}
+
+// ImportPaths returns the import paths to use for the given command line.
+//
+// The path "all" is expanded to all packages in $GOPATH and $GOROOT.
+// The path "std" is expanded to all packages in the Go standard library.
+// The path "cmd" is expanded to all Go standard commands.
+// The string "..." is treated as a wildcard within a path.
+// When matching recursively, directories are ignored if they are prefixed with
+// a dot or an underscore (such as ".foo" or "_foo"), or are named "testdata".
+// Relative import paths are not converted to full import paths.
+// If args is empty, a single element "." is returned.
+func (c *Context) ImportPaths(args []string) []string {
+	return c.importPaths(args)
+}
+
+// ImportPaths returns the import paths to use for the given command line
+// using default context.
+//
+// The path "all" is expanded to all packages in $GOPATH and $GOROOT.
+// The path "std" is expanded to all packages in the Go standard library.
+// The path "cmd" is expanded to all Go standard commands.
+// The string "..." is treated as a wildcard within a path.
+// When matching recursively, directories are ignored if they are prefixed with
+// a dot or an underscore (such as ".foo" or "_foo"), or are named "testdata".
+// Relative import paths are not converted to full import paths.
+// If args is empty, a single element "." is returned.
+func ImportPaths(args []string) []string {
+	return DefaultContext.importPaths(args)
+}

vendor/golang.org/x/tools/go/types/typeutil/callee.go

@@ -0,0 +1,46 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package typeutil
+
+import (
+	"go/ast"
+	"go/types"
+
+	"golang.org/x/tools/go/ast/astutil"
+)
+
+// Callee returns the named target of a function call, if any:
+// a function, method, builtin, or variable.
+func Callee(info *types.Info, call *ast.CallExpr) types.Object {
+	var obj types.Object
+	switch fun := astutil.Unparen(call.Fun).(type) {
+	case *ast.Ident:
+		obj = info.Uses[fun] // type, var, builtin, or declared func
+	case *ast.SelectorExpr:
+		if sel, ok := info.Selections[fun]; ok {
+			obj = sel.Obj() // method or field
+		} else {
+			obj = info.Uses[fun.Sel] // qualified identifier?
+		}
+	}
+	if _, ok := obj.(*types.TypeName); ok {
+		return nil // T(x) is a conversion, not a call
+	}
+	return obj
+}
+
+// StaticCallee returns the target (function or method) of a static
+// function call, if any. It returns nil for calls to builtins.
+func StaticCallee(info *types.Info, call *ast.CallExpr) *types.Func {
+	if f, ok := Callee(info, call).(*types.Func); ok && !interfaceMethod(f) {
+		return f
+	}
+	return nil
+}
+
+func interfaceMethod(f *types.Func) bool {
+	recv := f.Type().(*types.Signature).Recv()
+	return recv != nil && types.IsInterface(recv.Type())
+}

vendor/golang.org/x/tools/go/types/typeutil/imports.go

@@ -0,0 +1,31 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package typeutil
+
+import "go/types"
+
+// Dependencies returns all dependencies of the specified packages.
+//
+// Dependent packages appear in topological order: if package P imports
+// package Q, Q appears earlier than P in the result.
+// The algorithm follows import statements in the order they
+// appear in the source code, so the result is a total order.
+//
+func Dependencies(pkgs ...*types.Package) []*types.Package {
+	var result []*types.Package
+	seen := make(map[*types.Package]bool)
+	var visit func(pkgs []*types.Package)
+	visit = func(pkgs []*types.Package) {
+		for _, p := range pkgs {
+			if !seen[p] {
+				seen[p] = true
+				visit(p.Imports())
+				result = append(result, p)
+			}
+		}
+	}
+	visit(pkgs)
+	return result
+}

vendor/golang.org/x/tools/go/types/typeutil/map.go

@@ -0,0 +1,313 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package typeutil defines various utilities for types, such as Map,
+// a mapping from types.Type to interface{} values.
+package typeutil // import "golang.org/x/tools/go/types/typeutil"
+
+import (
+	"bytes"
+	"fmt"
+	"go/types"
+	"reflect"
+)
+
+// Map is a hash-table-based mapping from types (types.Type) to
+// arbitrary interface{} values.  The concrete types that implement
+// the Type interface are pointers.  Since they are not canonicalized,
+// == cannot be used to check for equivalence, and thus we cannot
+// simply use a Go map.
+//
+// Just as with map[K]V, a nil *Map is a valid empty map.
+//
+// Not thread-safe.
+//
+type Map struct {
+	hasher Hasher             // shared by many Maps
+	table  map[uint32][]entry // maps hash to bucket; entry.key==nil means unused
+	length int                // number of map entries
+}
+
+// entry is an entry (key/value association) in a hash bucket.
+type entry struct {
+	key   types.Type
+	value interface{}
+}
+
+// SetHasher sets the hasher used by Map.
+//
+// All Hashers are functionally equivalent but contain internal state
+// used to cache the results of hashing previously seen types.
+//
+// A single Hasher created by MakeHasher() may be shared among many
+// Maps.  This is recommended if the instances have many keys in
+// common, as it will amortize the cost of hash computation.
+//
+// A Hasher may grow without bound as new types are seen.  Even when a
+// type is deleted from the map, the Hasher never shrinks, since other
+// types in the map may reference the deleted type indirectly.
+//
+// Hashers are not thread-safe, and read-only operations such as
+// Map.Lookup require updates to the hasher, so a full Mutex lock (not a
+// read-lock) is require around all Map operations if a shared
+// hasher is accessed from multiple threads.
+//
+// If SetHasher is not called, the Map will create a private hasher at
+// the first call to Insert.
+//
+func (m *Map) SetHasher(hasher Hasher) {
+	m.hasher = hasher
+}
+
+// Delete removes the entry with the given key, if any.
+// It returns true if the entry was found.
+//
+func (m *Map) Delete(key types.Type) bool {
+	if m != nil && m.table != nil {
+		hash := m.hasher.Hash(key)
+		bucket := m.table[hash]
+		for i, e := range bucket {
+			if e.key != nil && types.Identical(key, e.key) {
+				// We can't compact the bucket as it
+				// would disturb iterators.
+				bucket[i] = entry{}
+				m.length--
+				return true
+			}
+		}
+	}
+	return false
+}
+
+// At returns the map entry for the given key.
+// The result is nil if the entry is not present.
+//
+func (m *Map) At(key types.Type) interface{} {
+	if m != nil && m.table != nil {
+		for _, e := range m.table[m.hasher.Hash(key)] {
+			if e.key != nil && types.Identical(key, e.key) {
+				return e.value
+			}
+		}
+	}
+	return nil
+}
+
+// Set sets the map entry for key to val,
+// and returns the previous entry, if any.
+func (m *Map) Set(key types.Type, value interface{}) (prev interface{}) {
+	if m.table != nil {
+		hash := m.hasher.Hash(key)
+		bucket := m.table[hash]
+		var hole *entry
+		for i, e := range bucket {
+			if e.key == nil {
+				hole = &bucket[i]
+			} else if types.Identical(key, e.key) {
+				prev = e.value
+				bucket[i].value = value
+				return
+			}
+		}
+
+		if hole != nil {
+			*hole = entry{key, value} // overwrite deleted entry
+		} else {
+			m.table[hash] = append(bucket, entry{key, value})
+		}
+	} else {
+		if m.hasher.memo == nil {
+			m.hasher = MakeHasher()
+		}
+		hash := m.hasher.Hash(key)
+		m.table = map[uint32][]entry{hash: {entry{key, value}}}
+	}
+
+	m.length++
+	return
+}
+
+// Len returns the number of map entries.
+func (m *Map) Len() int {
+	if m != nil {
+		return m.length
+	}
+	return 0
+}
+
+// Iterate calls function f on each entry in the map in unspecified order.
+//
+// If f should mutate the map, Iterate provides the same guarantees as
+// Go maps: if f deletes a map entry that Iterate has not yet reached,
+// f will not be invoked for it, but if f inserts a map entry that
+// Iterate has not yet reached, whether or not f will be invoked for
+// it is unspecified.
+//
+func (m *Map) Iterate(f func(key types.Type, value interface{})) {
+	if m != nil {
+		for _, bucket := range m.table {
+			for _, e := range bucket {
+				if e.key != nil {
+					f(e.key, e.value)
+				}
+			}
+		}
+	}
+}
+
+// Keys returns a new slice containing the set of map keys.
+// The order is unspecified.
+func (m *Map) Keys() []types.Type {
+	keys := make([]types.Type, 0, m.Len())
+	m.Iterate(func(key types.Type, _ interface{}) {
+		keys = append(keys, key)
+	})
+	return keys
+}
+
+func (m *Map) toString(values bool) string {
+	if m == nil {
+		return "{}"
+	}
+	var buf bytes.Buffer
+	fmt.Fprint(&buf, "{")
+	sep := ""
+	m.Iterate(func(key types.Type, value interface{}) {
+		fmt.Fprint(&buf, sep)
+		sep = ", "
+		fmt.Fprint(&buf, key)
+		if values {
+			fmt.Fprintf(&buf, ": %q", value)
+		}
+	})
+	fmt.Fprint(&buf, "}")
+	return buf.String()
+}
+
+// String returns a string representation of the map's entries.
+// Values are printed using fmt.Sprintf("%v", v).
+// Order is unspecified.
+//
+func (m *Map) String() string {
+	return m.toString(true)
+}
+
+// KeysString returns a string representation of the map's key set.
+// Order is unspecified.
+//
+func (m *Map) KeysString() string {
+	return m.toString(false)
+}
+
+////////////////////////////////////////////////////////////////////////
+// Hasher
+
+// A Hasher maps each type to its hash value.
+// For efficiency, a hasher uses memoization; thus its memory
+// footprint grows monotonically over time.
+// Hashers are not thread-safe.
+// Hashers have reference semantics.
+// Call MakeHasher to create a Hasher.
+type Hasher struct {
+	memo map[types.Type]uint32
+}
+
+// MakeHasher returns a new Hasher instance.
+func MakeHasher() Hasher {
+	return Hasher{make(map[types.Type]uint32)}
+}
+
+// Hash computes a hash value for the given type t such that
+// Identical(t, t') => Hash(t) == Hash(t').
+func (h Hasher) Hash(t types.Type) uint32 {
+	hash, ok := h.memo[t]
+	if !ok {
+		hash = h.hashFor(t)
+		h.memo[t] = hash
+	}
+	return hash
+}
+
+// hashString computes the Fowler–Noll–Vo hash of s.
+func hashString(s string) uint32 {
+	var h uint32
+	for i := 0; i < len(s); i++ {
+		h ^= uint32(s[i])
+		h *= 16777619
+	}
+	return h
+}
+
+// hashFor computes the hash of t.
+func (h Hasher) hashFor(t types.Type) uint32 {
+	// See Identical for rationale.
+	switch t := t.(type) {
+	case *types.Basic:
+		return uint32(t.Kind())
+
+	case *types.Array:
+		return 9043 + 2*uint32(t.Len()) + 3*h.Hash(t.Elem())
+
+	case *types.Slice:
+		return 9049 + 2*h.Hash(t.Elem())
+
+	case *types.Struct:
+		var hash uint32 = 9059
+		for i, n := 0, t.NumFields(); i < n; i++ {
+			f := t.Field(i)
+			if f.Anonymous() {
+				hash += 8861
+			}
+			hash += hashString(t.Tag(i))
+			hash += hashString(f.Name()) // (ignore f.Pkg)
+			hash += h.Hash(f.Type())
+		}
+		return hash
+
+	case *types.Pointer:
+		return 9067 + 2*h.Hash(t.Elem())
+
+	case *types.Signature:
+		var hash uint32 = 9091
+		if t.Variadic() {
+			hash *= 8863
+		}
+		return hash + 3*h.hashTuple(t.Params()) + 5*h.hashTuple(t.Results())
+
+	case *types.Interface:
+		var hash uint32 = 9103
+		for i, n := 0, t.NumMethods(); i < n; i++ {
+			// See go/types.identicalMethods for rationale.
+			// Method order is not significant.
+			// Ignore m.Pkg().
+			m := t.Method(i)
+			hash += 3*hashString(m.Name()) + 5*h.Hash(m.Type())
+		}
+		return hash
+
+	case *types.Map:
+		return 9109 + 2*h.Hash(t.Key()) + 3*h.Hash(t.Elem())
+
+	case *types.Chan:
+		return 9127 + 2*uint32(t.Dir()) + 3*h.Hash(t.Elem())
+
+	case *types.Named:
+		// Not safe with a copying GC; objects may move.
+		return uint32(reflect.ValueOf(t.Obj()).Pointer())
+
+	case *types.Tuple:
+		return h.hashTuple(t)
+	}
+	panic(t)
+}
+
+func (h Hasher) hashTuple(tuple *types.Tuple) uint32 {
+	// See go/types.identicalTypes for rationale.
+	n := tuple.Len()
+	var hash uint32 = 9137 + 2*uint32(n)
+	for i := 0; i < n; i++ {
+		hash += 3 * h.Hash(tuple.At(i).Type())
+	}
+	return hash
+}

vendor/golang.org/x/tools/go/types/typeutil/methodsetcache.go

@@ -0,0 +1,72 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file implements a cache of method sets.
+
+package typeutil
+
+import (
+	"go/types"
+	"sync"
+)
+
+// A MethodSetCache records the method set of each type T for which
+// MethodSet(T) is called so that repeat queries are fast.
+// The zero value is a ready-to-use cache instance.
+type MethodSetCache struct {
+	mu     sync.Mutex
+	named  map[*types.Named]struct{ value, pointer *types.MethodSet } // method sets for named N and *N
+	others map[types.Type]*types.MethodSet                            // all other types
+}
+
+// MethodSet returns the method set of type T.  It is thread-safe.
+//
+// If cache is nil, this function is equivalent to types.NewMethodSet(T).
+// Utility functions can thus expose an optional *MethodSetCache
+// parameter to clients that care about performance.
+//
+func (cache *MethodSetCache) MethodSet(T types.Type) *types.MethodSet {
+	if cache == nil {
+		return types.NewMethodSet(T)
+	}
+	cache.mu.Lock()
+	defer cache.mu.Unlock()
+
+	switch T := T.(type) {
+	case *types.Named:
+		return cache.lookupNamed(T).value
+
+	case *types.Pointer:
+		if N, ok := T.Elem().(*types.Named); ok {
+			return cache.lookupNamed(N).pointer
+		}
+	}
+
+	// all other types
+	// (The map uses pointer equivalence, not type identity.)
+	mset := cache.others[T]
+	if mset == nil {
+		mset = types.NewMethodSet(T)
+		if cache.others == nil {
+			cache.others = make(map[types.Type]*types.MethodSet)
+		}
+		cache.others[T] = mset
+	}
+	return mset
+}
+
+func (cache *MethodSetCache) lookupNamed(named *types.Named) struct{ value, pointer *types.MethodSet } {
+	if cache.named == nil {
+		cache.named = make(map[*types.Named]struct{ value, pointer *types.MethodSet })
+	}
+	// Avoid recomputing mset(*T) for each distinct Pointer
+	// instance whose underlying type is a named type.
+	msets, ok := cache.named[named]
+	if !ok {
+		msets.value = types.NewMethodSet(named)
+		msets.pointer = types.NewMethodSet(types.NewPointer(named))
+		cache.named[named] = msets
+	}
+	return msets
+}

vendor/golang.org/x/tools/go/types/typeutil/ui.go

@@ -0,0 +1,52 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package typeutil
+
+// This file defines utilities for user interfaces that display types.
+
+import "go/types"
+
+// IntuitiveMethodSet returns the intuitive method set of a type T,
+// which is the set of methods you can call on an addressable value of
+// that type.
+//
+// The result always contains MethodSet(T), and is exactly MethodSet(T)
+// for interface types and for pointer-to-concrete types.
+// For all other concrete types T, the result additionally
+// contains each method belonging to *T if there is no identically
+// named method on T itself.
+//
+// This corresponds to user intuition about method sets;
+// this function is intended only for user interfaces.
+//
+// The order of the result is as for types.MethodSet(T).
+//
+func IntuitiveMethodSet(T types.Type, msets *MethodSetCache) []*types.Selection {
+	isPointerToConcrete := func(T types.Type) bool {
+		ptr, ok := T.(*types.Pointer)
+		return ok && !types.IsInterface(ptr.Elem())
+	}
+
+	var result []*types.Selection
+	mset := msets.MethodSet(T)
+	if types.IsInterface(T) || isPointerToConcrete(T) {
+		for i, n := 0, mset.Len(); i < n; i++ {
+			result = append(result, mset.At(i))
+		}
+	} else {
+		// T is some other concrete type.
+		// Report methods of T and *T, preferring those of T.
+		pmset := msets.MethodSet(types.NewPointer(T))
+		for i, n := 0, pmset.Len(); i < n; i++ {
+			meth := pmset.At(i)
+			if m := mset.Lookup(meth.Obj().Pkg(), meth.Obj().Name()); m != nil {
+				meth = m
+			}
+			result = append(result, meth)
+		}
+
+	}
+	return result
+}

vendor/honnef.co/go/tools/LICENSE

@@ -0,0 +1,20 @@
+Copyright (c) 2016 Dominik Honnef
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

vendor/honnef.co/go/tools/cmd/gosimple/README.md

@@ -0,0 +1,15 @@
+# gosimple
+
+_gosimple_ is a linter for Go source code that specialises on
+simplifying code.
+
+## Installation
+
+Gosimple requires Go 1.6 or later.
+
+    go get honnef.co/go/tools/cmd/gosimple
+
+## Documentation
+
+Detailed documentation can be found on
+[staticcheck.io](https://staticcheck.io/docs/gosimple).

vendor/honnef.co/go/tools/cmd/gosimple/gosimple.go

@@ -0,0 +1,21 @@
+// gosimple detects code that could be rewritten in a simpler way.
+package main // import "honnef.co/go/tools/cmd/gosimple"
+import (
+	"os"
+
+	"honnef.co/go/tools/lint/lintutil"
+	"honnef.co/go/tools/simple"
+)
+
+func main() {
+	fs := lintutil.FlagSet("gosimple")
+	gen := fs.Bool("generated", false, "Check generated code")
+	fs.Parse(os.Args[1:])
+	c := simple.NewChecker()
+	c.CheckGenerated = *gen
+	cfg := lintutil.CheckerConfig{
+		Checker:     c,
+		ExitNonZero: true,
+	}
+	lintutil.ProcessFlagSet([]lintutil.CheckerConfig{cfg}, fs)
+}

vendor/honnef.co/go/tools/cmd/unused/README.md

@@ -0,0 +1,131 @@
+# unused
+
+_unused_ checks Go code for unused constants, variables, functions and
+types.
+
+## Install
+
+	go get honnef.co/go/tools/cmd/unused
+
+## Usage
+
+	unused -help
+
+## Usage Tips
+
+- When running _unused_ on multiple packages, it will first try to
+  check them all at once, because that's faster. If any of the
+  packages don't compile, however, _unused_ will check each package
+  individually.
+
+  The first step can, depending on the number of packages, use a lot
+  of memory. For the entire standard library, it uses roughly 800 MB.
+  For a GOPATH with thousands of packages, it can quickly use several
+  gigabytes. If that is an issue, consider using something like this
+  instead:
+
+  ```
+  for pkg in $(go list your_selection); do unused "$pkg"; done
+  ```
+
+  This will effectively skip the first step and always check every
+  package individually.
+
+## What counts as used/unused?
+
+_unused_ checks for unused constants, functions, types and optionally
+struct fields. They will be considered used or unused under the
+following conditions:
+
+- Unexported package-level objects will be reported as unused if there
+  are no explicit references to them.
+
+- Unexported methods will be reported as unused if there are no
+  explicit references to them and if they don't implement any
+  interfaces.
+
+- The `main` function is considered as used if it's in the `main`
+  package.
+
+- `init` functions are always considered as used.
+
+- Exported objects in function scope are treated like unexported
+  objects.
+
+- Exported functions in tests are treated like unexported functions,
+  unless they're test, benchmark or example functions.
+
+- Struct fields will be considered as unused if there are no explicit
+  references to them. Unkeyed composite literals with >=1 elements
+  mark all fields of the struct as used.
+
+- Neither the checks for methods nor for struct fields are aware of
+  the reflect package and may thus produce false positives.
+
+## Whole program analysis
+
+Optionally via the `-exported` flag, _unused_ can analyse all
+arguments as a single program and report unused exported identifiers.
+This can be useful for checking "internal" packages, or large software
+projects that do not export an API to the public, but use exported
+methods between components.
+
+Do note that in the whole-program analysis, all arguments must
+type-check. It is not possible to check packages individually in this
+mode.
+
+## Examples
+
+```
+$ time unused cmd/go
+/usr/lib/go/src/cmd/go/build.go:1327:6: func hasString is unused
+/usr/lib/go/src/cmd/go/build.go:2328:6: func toolVerify is unused
+/usr/lib/go/src/cmd/go/generate.go:375:21: func identLength is unused
+/usr/lib/go/src/cmd/go/get.go:474:5: var goTag is unused
+/usr/lib/go/src/cmd/go/get.go:513:6: func cmpGoVersion is unused
+/usr/lib/go/src/cmd/go/go_test.go:426:23: func grepCountStdout is unused
+/usr/lib/go/src/cmd/go/go_test.go:432:23: func grepCountStderr is unused
+/usr/lib/go/src/cmd/go/main.go:406:5: var logf is unused
+/usr/lib/go/src/cmd/go/main.go:431:6: func runOut is unused
+/usr/lib/go/src/cmd/go/pkg.go:91:2: field forceBuild is unused
+/usr/lib/go/src/cmd/go/pkg.go:688:2: const toRoot is unused
+/usr/lib/go/src/cmd/go/testflag.go:278:6: func setIntFlag is unused
+unused cmd/go  3.33s user 0.25s system 447% cpu 0.799 total
+```
+
+```
+$ time unused $(go list github.com/prometheus/prometheus/... | grep -v /vendor/)
+/home/dominikh/prj/src/github.com/prometheus/prometheus/promql/engine_test.go:11:5: var noop is unused
+/home/dominikh/prj/src/github.com/prometheus/prometheus/retrieval/discovery/dns.go:39:2: const interval is unused
+/home/dominikh/prj/src/github.com/prometheus/prometheus/retrieval/discovery/dns.go:69:2: field m is unused
+/home/dominikh/prj/src/github.com/prometheus/prometheus/retrieval/discovery/nerve.go:31:2: const nerveNodePrefix is unused
+/home/dominikh/prj/src/github.com/prometheus/prometheus/retrieval/discovery/serverset.go:33:2: const serversetNodePrefix is unused
+/home/dominikh/prj/src/github.com/prometheus/prometheus/retrieval/scrape.go:41:2: const ingestedSamplesCap is unused
+/home/dominikh/prj/src/github.com/prometheus/prometheus/retrieval/scrape.go:49:2: var errSkippedScrape is unused
+/home/dominikh/prj/src/github.com/prometheus/prometheus/retrieval/targetmanager.go:184:2: field providers is unused
+/home/dominikh/prj/src/github.com/prometheus/prometheus/storage/local/delta.go:394:2: field error is unused
+/home/dominikh/prj/src/github.com/prometheus/prometheus/storage/local/delta.go:398:3: field error is unused
+/home/dominikh/prj/src/github.com/prometheus/prometheus/storage/local/doubledelta.go:500:2: field error is unused
+/home/dominikh/prj/src/github.com/prometheus/prometheus/storage/local/doubledelta.go:504:3: field error is unused
+/home/dominikh/prj/src/github.com/prometheus/prometheus/storage/remote/opentsdb/client.go:40:2: var illegalCharsRE is unused
+/home/dominikh/prj/src/github.com/prometheus/prometheus/util/stats/timer.go:56:2: field child is unused
+/home/dominikh/prj/src/github.com/prometheus/prometheus/util/treecache/treecache.go:25:2: field zkEvents is unused
+unused $(go list github.com/prometheus/prometheus/... | grep -v /vendor/)  5.70s user 0.43s system 535% cpu 1.142 total
+```
+
+```
+$ time unused -exported github.com/kr/pretty/...
+/home/dominikh/prj/src/github.com/kr/pretty/formatter.go:14:2: const limit is unused
+/home/dominikh/prj/src/github.com/kr/pretty/formatter.go:322:6: func tryDeepEqual is unused
+/home/dominikh/prj/src/github.com/kr/pretty/pretty.go:20:6: func Errorf is unused
+/home/dominikh/prj/src/github.com/kr/pretty/pretty.go:28:6: func Fprintf is unused
+/home/dominikh/prj/src/github.com/kr/pretty/pretty.go:37:6: func Log is unused
+/home/dominikh/prj/src/github.com/kr/pretty/pretty.go:45:6: func Logf is unused
+/home/dominikh/prj/src/github.com/kr/pretty/pretty.go:54:6: func Logln is unused
+/home/dominikh/prj/src/github.com/kr/pretty/pretty.go:63:6: func Print is unused
+/home/dominikh/prj/src/github.com/kr/pretty/pretty.go:71:6: func Printf is unused
+/home/dominikh/prj/src/github.com/kr/pretty/pretty.go:80:6: func Println is unused
+/home/dominikh/prj/src/github.com/kr/pretty/pretty.go:88:6: func Sprintf is unused
+/home/dominikh/prj/src/github.com/kr/pretty/pretty.go:92:6: func wrap is unused
+unused -exported github.com/kr/pretty/...  1.23s user 0.19s system 253% cpu 0.558 total
+```

vendor/honnef.co/go/tools/cmd/unused/main.go

@@ -0,0 +1,78 @@
+// unused reports unused identifiers (types, functions, ...) in your
+// code.
+package main // import "honnef.co/go/tools/cmd/unused"
+
+import (
+	"log"
+	"os"
+
+	"honnef.co/go/tools/lint/lintutil"
+	"honnef.co/go/tools/unused"
+)
+
+var (
+	fConstants    bool
+	fFields       bool
+	fFunctions    bool
+	fTypes        bool
+	fVariables    bool
+	fDebug        string
+	fWholeProgram bool
+	fReflection   bool
+)
+
+func newChecker(mode unused.CheckMode) *unused.Checker {
+	checker := unused.NewChecker(mode)
+
+	if fDebug != "" {
+		debug, err := os.Create(fDebug)
+		if err != nil {
+			log.Fatal("couldn't open debug file:", err)
+		}
+		checker.Debug = debug
+	}
+
+	checker.WholeProgram = fWholeProgram
+	checker.ConsiderReflection = fReflection
+	return checker
+}
+
+func main() {
+	log.SetFlags(0)
+
+	fs := lintutil.FlagSet("unused")
+	fs.BoolVar(&fConstants, "consts", true, "Report unused constants")
+	fs.BoolVar(&fFields, "fields", true, "Report unused fields")
+	fs.BoolVar(&fFunctions, "funcs", true, "Report unused functions and methods")
+	fs.BoolVar(&fTypes, "types", true, "Report unused types")
+	fs.BoolVar(&fVariables, "vars", true, "Report unused variables")
+	fs.StringVar(&fDebug, "debug", "", "Write a debug graph to `file`. Existing files will be overwritten.")
+	fs.BoolVar(&fWholeProgram, "exported", false, "Treat arguments as a program and report unused exported identifiers")
+	fs.BoolVar(&fReflection, "reflect", true, "Consider identifiers as used when it's likely they'll be accessed via reflection")
+	fs.Parse(os.Args[1:])
+
+	var mode unused.CheckMode
+	if fConstants {
+		mode |= unused.CheckConstants
+	}
+	if fFields {
+		mode |= unused.CheckFields
+	}
+	if fFunctions {
+		mode |= unused.CheckFunctions
+	}
+	if fTypes {
+		mode |= unused.CheckTypes
+	}
+	if fVariables {
+		mode |= unused.CheckVariables
+	}
+
+	checker := newChecker(mode)
+	l := unused.NewLintChecker(checker)
+	cfg := lintutil.CheckerConfig{
+		Checker:     l,
+		ExitNonZero: true,
+	}
+	lintutil.ProcessFlagSet([]lintutil.CheckerConfig{cfg}, fs)
+}

vendor/honnef.co/go/tools/internal/sharedcheck/lint.go

@@ -0,0 +1,68 @@
+package sharedcheck
+
+import (
+	"go/ast"
+	"go/types"
+
+	"honnef.co/go/tools/lint"
+	. "honnef.co/go/tools/lint/lintdsl"
+	"honnef.co/go/tools/ssa"
+)
+
+func CheckRangeStringRunes(j *lint.Job) {
+	for _, ssafn := range j.Program.InitialFunctions {
+		fn := func(node ast.Node) bool {
+			rng, ok := node.(*ast.RangeStmt)
+			if !ok || !IsBlank(rng.Key) {
+				return true
+			}
+
+			v, _ := ssafn.ValueForExpr(rng.X)
+
+			// Check that we're converting from string to []rune
+			val, _ := v.(*ssa.Convert)
+			if val == nil {
+				return true
+			}
+			Tsrc, ok := val.X.Type().(*types.Basic)
+			if !ok || Tsrc.Kind() != types.String {
+				return true
+			}
+			Tdst, ok := val.Type().(*types.Slice)
+			if !ok {
+				return true
+			}
+			TdstElem, ok := Tdst.Elem().(*types.Basic)
+			if !ok || TdstElem.Kind() != types.Int32 {
+				return true
+			}
+
+			// Check that the result of the conversion is only used to
+			// range over
+			refs := val.Referrers()
+			if refs == nil {
+				return true
+			}
+
+			// Expect two refs: one for obtaining the length of the slice,
+			// one for accessing the elements
+			if len(FilterDebug(*refs)) != 2 {
+				// TODO(dh): right now, we check that only one place
+				// refers to our slice. This will miss cases such as
+				// ranging over the slice twice. Ideally, we'd ensure that
+				// the slice is only used for ranging over (without
+				// accessing the key), but that is harder to do because in
+				// SSA form, ranging over a slice looks like an ordinary
+				// loop with index increments and slice accesses. We'd
+				// have to look at the associated AST node to check that
+				// it's a range statement.
+				return true
+			}
+
+			j.Errorf(rng, "should range over string, not []rune(string)")
+
+			return true
+		}
+		Inspect(ssafn.Syntax(), fn)
+	}
+}

vendor/honnef.co/go/tools/lint/LICENSE

@@ -0,0 +1,28 @@
+Copyright (c) 2013 The Go Authors. All rights reserved.
+Copyright (c) 2016 Dominik Honnef. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/honnef.co/go/tools/lint/lint.go

@@ -0,0 +1,543 @@
+// Copyright (c) 2013 The Go Authors. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd.
+
+// Package lint provides the foundation for tools like gosimple.
+package lint // import "honnef.co/go/tools/lint"
+
+import (
+	"fmt"
+	"go/ast"
+	"go/build"
+	"go/token"
+	"go/types"
+	"path/filepath"
+	"sort"
+	"strings"
+	"sync"
+	"unicode"
+
+	"golang.org/x/tools/go/loader"
+	"honnef.co/go/tools/ssa"
+	"honnef.co/go/tools/ssa/ssautil"
+)
+
+type Job struct {
+	Program *Program
+
+	checker  string
+	check    string
+	problems []Problem
+}
+
+type Ignore interface {
+	Match(p Problem) bool
+}
+
+type LineIgnore struct {
+	File    string
+	Line    int
+	Checks  []string
+	matched bool
+	pos     token.Pos
+}
+
+func (li *LineIgnore) Match(p Problem) bool {
+	if p.Position.Filename != li.File || p.Position.Line != li.Line {
+		return false
+	}
+	for _, c := range li.Checks {
+		if m, _ := filepath.Match(c, p.Check); m {
+			li.matched = true
+			return true
+		}
+	}
+	return false
+}
+
+func (li *LineIgnore) String() string {
+	matched := "not matched"
+	if li.matched {
+		matched = "matched"
+	}
+	return fmt.Sprintf("%s:%d %s (%s)", li.File, li.Line, strings.Join(li.Checks, ", "), matched)
+}
+
+type FileIgnore struct {
+	File   string
+	Checks []string
+}
+
+func (fi *FileIgnore) Match(p Problem) bool {
+	if p.Position.Filename != fi.File {
+		return false
+	}
+	for _, c := range fi.Checks {
+		if m, _ := filepath.Match(c, p.Check); m {
+			return true
+		}
+	}
+	return false
+}
+
+type GlobIgnore struct {
+	Pattern string
+	Checks  []string
+}
+
+func (gi *GlobIgnore) Match(p Problem) bool {
+	if gi.Pattern != "*" {
+		pkgpath := p.Package.Path()
+		if strings.HasSuffix(pkgpath, "_test") {
+			pkgpath = pkgpath[:len(pkgpath)-len("_test")]
+		}
+		name := filepath.Join(pkgpath, filepath.Base(p.Position.Filename))
+		if m, _ := filepath.Match(gi.Pattern, name); !m {
+			return false
+		}
+	}
+	for _, c := range gi.Checks {
+		if m, _ := filepath.Match(c, p.Check); m {
+			return true
+		}
+	}
+	return false
+}
+
+type Program struct {
+	SSA  *ssa.Program
+	Prog *loader.Program
+	// TODO(dh): Rename to InitialPackages?
+	Packages         []*Pkg
+	InitialFunctions []*ssa.Function
+	AllFunctions     []*ssa.Function
+	Files            []*ast.File
+	Info             *types.Info
+	GoVersion        int
+
+	tokenFileMap map[*token.File]*ast.File
+	astFileMap   map[*ast.File]*Pkg
+}
+
+type Func func(*Job)
+
+// Problem represents a problem in some source code.
+type Problem struct {
+	pos      token.Pos
+	Position token.Position // position in source file
+	Text     string         // the prose that describes the problem
+	Check    string
+	Checker  string
+	Package  *types.Package
+	Ignored  bool
+}
+
+func (p *Problem) String() string {
+	if p.Check == "" {
+		return p.Text
+	}
+	return fmt.Sprintf("%s (%s)", p.Text, p.Check)
+}
+
+type Checker interface {
+	Name() string
+	Prefix() string
+	Init(*Program)
+	Funcs() map[string]Func
+}
+
+// A Linter lints Go source code.
+type Linter struct {
+	Checker       Checker
+	Ignores       []Ignore
+	GoVersion     int
+	ReturnIgnored bool
+
+	automaticIgnores []Ignore
+}
+
+func (l *Linter) ignore(p Problem) bool {
+	ignored := false
+	for _, ig := range l.automaticIgnores {
+		// We cannot short-circuit these, as we want to record, for
+		// each ignore, whether it matched or not.
+		if ig.Match(p) {
+			ignored = true
+		}
+	}
+	if ignored {
+		// no need to execute other ignores if we've already had a
+		// match.
+		return true
+	}
+	for _, ig := range l.Ignores {
+		// We can short-circuit here, as we aren't tracking any
+		// information.
+		if ig.Match(p) {
+			return true
+		}
+	}
+
+	return false
+}
+
+func (prog *Program) File(node Positioner) *ast.File {
+	return prog.tokenFileMap[prog.SSA.Fset.File(node.Pos())]
+}
+
+func (j *Job) File(node Positioner) *ast.File {
+	return j.Program.File(node)
+}
+
+// TODO(dh): switch to sort.Slice when Go 1.9 lands.
+type byPosition struct {
+	fset *token.FileSet
+	ps   []Problem
+}
+
+func (ps byPosition) Len() int {
+	return len(ps.ps)
+}
+
+func (ps byPosition) Less(i int, j int) bool {
+	pi, pj := ps.ps[i].Position, ps.ps[j].Position
+
+	if pi.Filename != pj.Filename {
+		return pi.Filename < pj.Filename
+	}
+	if pi.Line != pj.Line {
+		return pi.Line < pj.Line
+	}
+	if pi.Column != pj.Column {
+		return pi.Column < pj.Column
+	}
+
+	return ps.ps[i].Text < ps.ps[j].Text
+}
+
+func (ps byPosition) Swap(i int, j int) {
+	ps.ps[i], ps.ps[j] = ps.ps[j], ps.ps[i]
+}
+
+func parseDirective(s string) (cmd string, args []string) {
+	if !strings.HasPrefix(s, "//lint:") {
+		return "", nil
+	}
+	s = strings.TrimPrefix(s, "//lint:")
+	fields := strings.Split(s, " ")
+	return fields[0], fields[1:]
+}
+
+func (l *Linter) Lint(lprog *loader.Program, conf *loader.Config) []Problem {
+	ssaprog := ssautil.CreateProgram(lprog, ssa.GlobalDebug)
+	ssaprog.Build()
+	pkgMap := map[*ssa.Package]*Pkg{}
+	var pkgs []*Pkg
+	for _, pkginfo := range lprog.InitialPackages() {
+		ssapkg := ssaprog.Package(pkginfo.Pkg)
+		var bp *build.Package
+		if len(pkginfo.Files) != 0 {
+			path := lprog.Fset.Position(pkginfo.Files[0].Pos()).Filename
+			dir := filepath.Dir(path)
+			var err error
+			ctx := conf.Build
+			if ctx == nil {
+				ctx = &build.Default
+			}
+			bp, err = ctx.ImportDir(dir, 0)
+			if err != nil {
+				// shouldn't happen
+			}
+		}
+		pkg := &Pkg{
+			Package:  ssapkg,
+			Info:     pkginfo,
+			BuildPkg: bp,
+		}
+		pkgMap[ssapkg] = pkg
+		pkgs = append(pkgs, pkg)
+	}
+	prog := &Program{
+		SSA:          ssaprog,
+		Prog:         lprog,
+		Packages:     pkgs,
+		Info:         &types.Info{},
+		GoVersion:    l.GoVersion,
+		tokenFileMap: map[*token.File]*ast.File{},
+		astFileMap:   map[*ast.File]*Pkg{},
+	}
+
+	initial := map[*types.Package]struct{}{}
+	for _, pkg := range pkgs {
+		initial[pkg.Info.Pkg] = struct{}{}
+	}
+	for fn := range ssautil.AllFunctions(ssaprog) {
+		if fn.Pkg == nil {
+			continue
+		}
+		prog.AllFunctions = append(prog.AllFunctions, fn)
+		if _, ok := initial[fn.Pkg.Pkg]; ok {
+			prog.InitialFunctions = append(prog.InitialFunctions, fn)
+		}
+	}
+	for _, pkg := range pkgs {
+		prog.Files = append(prog.Files, pkg.Info.Files...)
+
+		ssapkg := ssaprog.Package(pkg.Info.Pkg)
+		for _, f := range pkg.Info.Files {
+			prog.astFileMap[f] = pkgMap[ssapkg]
+		}
+	}
+
+	for _, pkginfo := range lprog.AllPackages {
+		for _, f := range pkginfo.Files {
+			tf := lprog.Fset.File(f.Pos())
+			prog.tokenFileMap[tf] = f
+		}
+	}
+
+	var out []Problem
+	l.automaticIgnores = nil
+	for _, pkginfo := range lprog.InitialPackages() {
+		for _, f := range pkginfo.Files {
+			cm := ast.NewCommentMap(lprog.Fset, f, f.Comments)
+			for node, cgs := range cm {
+				for _, cg := range cgs {
+					for _, c := range cg.List {
+						if !strings.HasPrefix(c.Text, "//lint:") {
+							continue
+						}
+						cmd, args := parseDirective(c.Text)
+						switch cmd {
+						case "ignore", "file-ignore":
+							if len(args) < 2 {
+								// FIXME(dh): this causes duplicated warnings when using megacheck
+								p := Problem{
+									pos:      c.Pos(),
+									Position: prog.DisplayPosition(c.Pos()),
+									Text:     "malformed linter directive; missing the required reason field?",
+									Check:    "",
+									Checker:  l.Checker.Name(),
+									Package:  nil,
+								}
+								out = append(out, p)
+								continue
+							}
+						default:
+							// unknown directive, ignore
+							continue
+						}
+						checks := strings.Split(args[0], ",")
+						pos := prog.DisplayPosition(node.Pos())
+						var ig Ignore
+						switch cmd {
+						case "ignore":
+							ig = &LineIgnore{
+								File:   pos.Filename,
+								Line:   pos.Line,
+								Checks: checks,
+								pos:    c.Pos(),
+							}
+						case "file-ignore":
+							ig = &FileIgnore{
+								File:   pos.Filename,
+								Checks: checks,
+							}
+						}
+						l.automaticIgnores = append(l.automaticIgnores, ig)
+					}
+				}
+			}
+		}
+	}
+
+	sizes := struct {
+		types      int
+		defs       int
+		uses       int
+		implicits  int
+		selections int
+		scopes     int
+	}{}
+	for _, pkg := range pkgs {
+		sizes.types += len(pkg.Info.Info.Types)
+		sizes.defs += len(pkg.Info.Info.Defs)
+		sizes.uses += len(pkg.Info.Info.Uses)
+		sizes.implicits += len(pkg.Info.Info.Implicits)
+		sizes.selections += len(pkg.Info.Info.Selections)
+		sizes.scopes += len(pkg.Info.Info.Scopes)
+	}
+	prog.Info.Types = make(map[ast.Expr]types.TypeAndValue, sizes.types)
+	prog.Info.Defs = make(map[*ast.Ident]types.Object, sizes.defs)
+	prog.Info.Uses = make(map[*ast.Ident]types.Object, sizes.uses)
+	prog.Info.Implicits = make(map[ast.Node]types.Object, sizes.implicits)
+	prog.Info.Selections = make(map[*ast.SelectorExpr]*types.Selection, sizes.selections)
+	prog.Info.Scopes = make(map[ast.Node]*types.Scope, sizes.scopes)
+	for _, pkg := range pkgs {
+		for k, v := range pkg.Info.Info.Types {
+			prog.Info.Types[k] = v
+		}
+		for k, v := range pkg.Info.Info.Defs {
+			prog.Info.Defs[k] = v
+		}
+		for k, v := range pkg.Info.Info.Uses {
+			prog.Info.Uses[k] = v
+		}
+		for k, v := range pkg.Info.Info.Implicits {
+			prog.Info.Implicits[k] = v
+		}
+		for k, v := range pkg.Info.Info.Selections {
+			prog.Info.Selections[k] = v
+		}
+		for k, v := range pkg.Info.Info.Scopes {
+			prog.Info.Scopes[k] = v
+		}
+	}
+	l.Checker.Init(prog)
+
+	funcs := l.Checker.Funcs()
+	var keys []string
+	for k := range funcs {
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
+
+	var jobs []*Job
+	for _, k := range keys {
+		j := &Job{
+			Program: prog,
+			checker: l.Checker.Name(),
+			check:   k,
+		}
+		jobs = append(jobs, j)
+	}
+	wg := &sync.WaitGroup{}
+	for _, j := range jobs {
+		wg.Add(1)
+		go func(j *Job) {
+			defer wg.Done()
+			fn := funcs[j.check]
+			if fn == nil {
+				return
+			}
+			fn(j)
+		}(j)
+	}
+	wg.Wait()
+
+	for _, j := range jobs {
+		for _, p := range j.problems {
+			p.Ignored = l.ignore(p)
+			if l.ReturnIgnored || !p.Ignored {
+				out = append(out, p)
+			}
+		}
+	}
+
+	for _, ig := range l.automaticIgnores {
+		ig, ok := ig.(*LineIgnore)
+		if !ok {
+			continue
+		}
+		if ig.matched {
+			continue
+		}
+		for _, c := range ig.Checks {
+			idx := strings.IndexFunc(c, func(r rune) bool {
+				return unicode.IsNumber(r)
+			})
+			if idx == -1 {
+				// malformed check name, backing out
+				continue
+			}
+			if c[:idx] != l.Checker.Prefix() {
+				// not for this checker
+				continue
+			}
+			p := Problem{
+				pos:      ig.pos,
+				Position: prog.DisplayPosition(ig.pos),
+				Text:     "this linter directive didn't match anything; should it be removed?",
+				Check:    "",
+				Checker:  l.Checker.Name(),
+				Package:  nil,
+			}
+			out = append(out, p)
+		}
+	}
+
+	sort.Sort(byPosition{lprog.Fset, out})
+	return out
+}
+
+// Pkg represents a package being linted.
+type Pkg struct {
+	*ssa.Package
+	Info     *loader.PackageInfo
+	BuildPkg *build.Package
+}
+
+type Positioner interface {
+	Pos() token.Pos
+}
+
+func (prog *Program) DisplayPosition(p token.Pos) token.Position {
+	// The //line compiler directive can be used to change the file
+	// name and line numbers associated with code. This can, for
+	// example, be used by code generation tools. The most prominent
+	// example is 'go tool cgo', which uses //line directives to refer
+	// back to the original source code.
+	//
+	// In the context of our linters, we need to treat these
+	// directives differently depending on context. For cgo files, we
+	// want to honour the directives, so that line numbers are
+	// adjusted correctly. For all other files, we want to ignore the
+	// directives, so that problems are reported at their actual
+	// position and not, for example, a yacc grammar file. This also
+	// affects the ignore mechanism, since it operates on the position
+	// information stored within problems. With this implementation, a
+	// user will ignore foo.go, not foo.y
+
+	pkg := prog.astFileMap[prog.tokenFileMap[prog.Prog.Fset.File(p)]]
+	bp := pkg.BuildPkg
+	adjPos := prog.Prog.Fset.Position(p)
+	if bp == nil {
+		// couldn't find the package for some reason (deleted? faulty
+		// file system?)
+		return adjPos
+	}
+	base := filepath.Base(adjPos.Filename)
+	for _, f := range bp.CgoFiles {
+		if f == base {
+			// this is a cgo file, use the adjusted position
+			return adjPos
+		}
+	}
+	// not a cgo file, ignore //line directives
+	return prog.Prog.Fset.PositionFor(p, false)
+}
+
+func (j *Job) Errorf(n Positioner, format string, args ...interface{}) *Problem {
+	tf := j.Program.SSA.Fset.File(n.Pos())
+	f := j.Program.tokenFileMap[tf]
+	pkg := j.Program.astFileMap[f].Pkg
+
+	pos := j.Program.DisplayPosition(n.Pos())
+	problem := Problem{
+		pos:      n.Pos(),
+		Position: pos,
+		Text:     fmt.Sprintf(format, args...),
+		Check:    j.check,
+		Checker:  j.checker,
+		Package:  pkg,
+	}
+	j.problems = append(j.problems, problem)
+	return &j.problems[len(j.problems)-1]
+}
+
+func (j *Job) NodePackage(node Positioner) *Pkg {
+	f := j.File(node)
+	return j.Program.astFileMap[f]
+}

vendor/honnef.co/go/tools/lint/lintdsl/lintdsl.go

@@ -0,0 +1,282 @@
+// Package lintdsl provides helpers for implementing static analysis
+// checks. Dot-importing this package is encouraged.
+package lintdsl
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/constant"
+	"go/printer"
+	"go/token"
+	"go/types"
+	"strings"
+
+	"honnef.co/go/tools/lint"
+	"honnef.co/go/tools/ssa"
+)
+
+type packager interface {
+	Package() *ssa.Package
+}
+
+func CallName(call *ssa.CallCommon) string {
+	if call.IsInvoke() {
+		return ""
+	}
+	switch v := call.Value.(type) {
+	case *ssa.Function:
+		fn, ok := v.Object().(*types.Func)
+		if !ok {
+			return ""
+		}
+		return fn.FullName()
+	case *ssa.Builtin:
+		return v.Name()
+	}
+	return ""
+}
+
+func IsCallTo(call *ssa.CallCommon, name string) bool { return CallName(call) == name }
+func IsType(T types.Type, name string) bool           { return types.TypeString(T, nil) == name }
+
+func FilterDebug(instr []ssa.Instruction) []ssa.Instruction {
+	var out []ssa.Instruction
+	for _, ins := range instr {
+		if _, ok := ins.(*ssa.DebugRef); !ok {
+			out = append(out, ins)
+		}
+	}
+	return out
+}
+
+func IsExample(fn *ssa.Function) bool {
+	if !strings.HasPrefix(fn.Name(), "Example") {
+		return false
+	}
+	f := fn.Prog.Fset.File(fn.Pos())
+	if f == nil {
+		return false
+	}
+	return strings.HasSuffix(f.Name(), "_test.go")
+}
+
+func IsPointerLike(T types.Type) bool {
+	switch T := T.Underlying().(type) {
+	case *types.Interface, *types.Chan, *types.Map, *types.Pointer:
+		return true
+	case *types.Basic:
+		return T.Kind() == types.UnsafePointer
+	}
+	return false
+}
+
+func IsGenerated(f *ast.File) bool {
+	comments := f.Comments
+	if len(comments) > 0 {
+		comment := comments[0].Text()
+		return strings.Contains(comment, "Code generated by") ||
+			strings.Contains(comment, "DO NOT EDIT")
+	}
+	return false
+}
+
+func IsIdent(expr ast.Expr, ident string) bool {
+	id, ok := expr.(*ast.Ident)
+	return ok && id.Name == ident
+}
+
+// isBlank returns whether id is the blank identifier "_".
+// If id == nil, the answer is false.
+func IsBlank(id ast.Expr) bool {
+	ident, _ := id.(*ast.Ident)
+	return ident != nil && ident.Name == "_"
+}
+
+func IsIntLiteral(expr ast.Expr, literal string) bool {
+	lit, ok := expr.(*ast.BasicLit)
+	return ok && lit.Kind == token.INT && lit.Value == literal
+}
+
+// Deprecated: use IsIntLiteral instead
+func IsZero(expr ast.Expr) bool {
+	return IsIntLiteral(expr, "0")
+}
+
+func TypeOf(j *lint.Job, expr ast.Expr) types.Type          { return j.Program.Info.TypeOf(expr) }
+func IsOfType(j *lint.Job, expr ast.Expr, name string) bool { return IsType(TypeOf(j, expr), name) }
+
+func ObjectOf(j *lint.Job, ident *ast.Ident) types.Object { return j.Program.Info.ObjectOf(ident) }
+
+func IsInTest(j *lint.Job, node lint.Positioner) bool {
+	// FIXME(dh): this doesn't work for global variables with
+	// initializers
+	f := j.Program.SSA.Fset.File(node.Pos())
+	return f != nil && strings.HasSuffix(f.Name(), "_test.go")
+}
+
+func IsInMain(j *lint.Job, node lint.Positioner) bool {
+	if node, ok := node.(packager); ok {
+		return node.Package().Pkg.Name() == "main"
+	}
+	pkg := j.NodePackage(node)
+	if pkg == nil {
+		return false
+	}
+	return pkg.Pkg.Name() == "main"
+}
+
+func SelectorName(j *lint.Job, expr *ast.SelectorExpr) string {
+	sel := j.Program.Info.Selections[expr]
+	if sel == nil {
+		if x, ok := expr.X.(*ast.Ident); ok {
+			pkg, ok := j.Program.Info.ObjectOf(x).(*types.PkgName)
+			if !ok {
+				// This shouldn't happen
+				return fmt.Sprintf("%s.%s", x.Name, expr.Sel.Name)
+			}
+			return fmt.Sprintf("%s.%s", pkg.Imported().Path(), expr.Sel.Name)
+		}
+		panic(fmt.Sprintf("unsupported selector: %v", expr))
+	}
+	return fmt.Sprintf("(%s).%s", sel.Recv(), sel.Obj().Name())
+}
+
+func IsNil(j *lint.Job, expr ast.Expr) bool {
+	return j.Program.Info.Types[expr].IsNil()
+}
+
+func BoolConst(j *lint.Job, expr ast.Expr) bool {
+	val := j.Program.Info.ObjectOf(expr.(*ast.Ident)).(*types.Const).Val()
+	return constant.BoolVal(val)
+}
+
+func IsBoolConst(j *lint.Job, expr ast.Expr) bool {
+	// We explicitly don't support typed bools because more often than
+	// not, custom bool types are used as binary enums and the
+	// explicit comparison is desired.
+
+	ident, ok := expr.(*ast.Ident)
+	if !ok {
+		return false
+	}
+	obj := j.Program.Info.ObjectOf(ident)
+	c, ok := obj.(*types.Const)
+	if !ok {
+		return false
+	}
+	basic, ok := c.Type().(*types.Basic)
+	if !ok {
+		return false
+	}
+	if basic.Kind() != types.UntypedBool && basic.Kind() != types.Bool {
+		return false
+	}
+	return true
+}
+
+func ExprToInt(j *lint.Job, expr ast.Expr) (int64, bool) {
+	tv := j.Program.Info.Types[expr]
+	if tv.Value == nil {
+		return 0, false
+	}
+	if tv.Value.Kind() != constant.Int {
+		return 0, false
+	}
+	return constant.Int64Val(tv.Value)
+}
+
+func ExprToString(j *lint.Job, expr ast.Expr) (string, bool) {
+	val := j.Program.Info.Types[expr].Value
+	if val == nil {
+		return "", false
+	}
+	if val.Kind() != constant.String {
+		return "", false
+	}
+	return constant.StringVal(val), true
+}
+
+// Dereference returns a pointer's element type; otherwise it returns
+// T.
+func Dereference(T types.Type) types.Type {
+	if p, ok := T.Underlying().(*types.Pointer); ok {
+		return p.Elem()
+	}
+	return T
+}
+
+// DereferenceR returns a pointer's element type; otherwise it returns
+// T. If the element type is itself a pointer, DereferenceR will be
+// applied recursively.
+func DereferenceR(T types.Type) types.Type {
+	if p, ok := T.Underlying().(*types.Pointer); ok {
+		return DereferenceR(p.Elem())
+	}
+	return T
+}
+
+func IsGoVersion(j *lint.Job, minor int) bool {
+	return j.Program.GoVersion >= minor
+}
+
+func IsCallToAST(j *lint.Job, node ast.Node, name string) bool {
+	call, ok := node.(*ast.CallExpr)
+	if !ok {
+		return false
+	}
+	sel, ok := call.Fun.(*ast.SelectorExpr)
+	if !ok {
+		return false
+	}
+	fn, ok := j.Program.Info.ObjectOf(sel.Sel).(*types.Func)
+	return ok && fn.FullName() == name
+}
+
+func IsCallToAnyAST(j *lint.Job, node ast.Node, names ...string) bool {
+	for _, name := range names {
+		if IsCallToAST(j, node, name) {
+			return true
+		}
+	}
+	return false
+}
+
+func Render(j *lint.Job, x interface{}) string {
+	fset := j.Program.SSA.Fset
+	var buf bytes.Buffer
+	if err := printer.Fprint(&buf, fset, x); err != nil {
+		panic(err)
+	}
+	return buf.String()
+}
+
+func RenderArgs(j *lint.Job, args []ast.Expr) string {
+	var ss []string
+	for _, arg := range args {
+		ss = append(ss, Render(j, arg))
+	}
+	return strings.Join(ss, ", ")
+}
+
+func Preamble(f *ast.File) string {
+	cutoff := f.Package
+	if f.Doc != nil {
+		cutoff = f.Doc.Pos()
+	}
+	var out []string
+	for _, cmt := range f.Comments {
+		if cmt.Pos() >= cutoff {
+			break
+		}
+		out = append(out, cmt.Text())
+	}
+	return strings.Join(out, "\n")
+}
+
+func Inspect(node ast.Node, fn func(node ast.Node) bool) {
+	if node == nil {
+		return
+	}
+	ast.Inspect(node, fn)
+}

vendor/honnef.co/go/tools/lint/lintutil/util.go

@@ -0,0 +1,350 @@
+// Copyright (c) 2013 The Go Authors. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd.
+
+// Package lintutil provides helpers for writing linter command lines.
+package lintutil // import "honnef.co/go/tools/lint/lintutil"
+
+import (
+	"encoding/json"
+	"errors"
+	"flag"
+	"fmt"
+	"go/build"
+	"go/parser"
+	"go/token"
+	"go/types"
+	"io"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"honnef.co/go/tools/lint"
+	"honnef.co/go/tools/version"
+
+	"github.com/kisielk/gotool"
+	"golang.org/x/tools/go/loader"
+)
+
+type OutputFormatter interface {
+	Format(p lint.Problem)
+}
+
+type TextOutput struct {
+	w io.Writer
+}
+
+func (o TextOutput) Format(p lint.Problem) {
+	fmt.Fprintf(o.w, "%v: %s\n", relativePositionString(p.Position), p.String())
+}
+
+type JSONOutput struct {
+	w io.Writer
+}
+
+func (o JSONOutput) Format(p lint.Problem) {
+	type location struct {
+		File   string `json:"file"`
+		Line   int    `json:"line"`
+		Column int    `json:"column"`
+	}
+	jp := struct {
+		Checker  string   `json:"checker"`
+		Code     string   `json:"code"`
+		Severity string   `json:"severity,omitempty"`
+		Location location `json:"location"`
+		Message  string   `json:"message"`
+		Ignored  bool     `json:"ignored"`
+	}{
+		p.Checker,
+		p.Check,
+		"", // TODO(dh): support severity
+		location{
+			p.Position.Filename,
+			p.Position.Line,
+			p.Position.Column,
+		},
+		p.Text,
+		p.Ignored,
+	}
+	_ = json.NewEncoder(o.w).Encode(jp)
+}
+func usage(name string, flags *flag.FlagSet) func() {
+	return func() {
+		fmt.Fprintf(os.Stderr, "Usage of %s:\n", name)
+		fmt.Fprintf(os.Stderr, "\t%s [flags] # runs on package in current directory\n", name)
+		fmt.Fprintf(os.Stderr, "\t%s [flags] packages\n", name)
+		fmt.Fprintf(os.Stderr, "\t%s [flags] directory\n", name)
+		fmt.Fprintf(os.Stderr, "\t%s [flags] files... # must be a single package\n", name)
+		fmt.Fprintf(os.Stderr, "Flags:\n")
+		flags.PrintDefaults()
+	}
+}
+
+type runner struct {
+	checker       lint.Checker
+	tags          []string
+	ignores       []lint.Ignore
+	version       int
+	returnIgnored bool
+}
+
+func resolveRelative(importPaths []string, tags []string) (goFiles bool, err error) {
+	if len(importPaths) == 0 {
+		return false, nil
+	}
+	if strings.HasSuffix(importPaths[0], ".go") {
+		// User is specifying a package in terms of .go files, don't resolve
+		return true, nil
+	}
+	wd, err := os.Getwd()
+	if err != nil {
+		return false, err
+	}
+	ctx := build.Default
+	ctx.BuildTags = tags
+	for i, path := range importPaths {
+		bpkg, err := ctx.Import(path, wd, build.FindOnly)
+		if err != nil {
+			return false, fmt.Errorf("can't load package %q: %v", path, err)
+		}
+		importPaths[i] = bpkg.ImportPath
+	}
+	return false, nil
+}
+
+func parseIgnore(s string) ([]lint.Ignore, error) {
+	var out []lint.Ignore
+	if len(s) == 0 {
+		return nil, nil
+	}
+	for _, part := range strings.Fields(s) {
+		p := strings.Split(part, ":")
+		if len(p) != 2 {
+			return nil, errors.New("malformed ignore string")
+		}
+		path := p[0]
+		checks := strings.Split(p[1], ",")
+		out = append(out, &lint.GlobIgnore{Pattern: path, Checks: checks})
+	}
+	return out, nil
+}
+
+type versionFlag int
+
+func (v *versionFlag) String() string {
+	return fmt.Sprintf("1.%d", *v)
+}
+
+func (v *versionFlag) Set(s string) error {
+	if len(s) < 3 {
+		return errors.New("invalid Go version")
+	}
+	if s[0] != '1' {
+		return errors.New("invalid Go version")
+	}
+	if s[1] != '.' {
+		return errors.New("invalid Go version")
+	}
+	i, err := strconv.Atoi(s[2:])
+	*v = versionFlag(i)
+	return err
+}
+
+func (v *versionFlag) Get() interface{} {
+	return int(*v)
+}
+
+func FlagSet(name string) *flag.FlagSet {
+	flags := flag.NewFlagSet("", flag.ExitOnError)
+	flags.Usage = usage(name, flags)
+	flags.Float64("min_confidence", 0, "Deprecated; use -ignore instead")
+	flags.String("tags", "", "List of `build tags`")
+	flags.String("ignore", "", "Space separated list of checks to ignore, in the following format: 'import/path/file.go:Check1,Check2,...' Both the import path and file name sections support globbing, e.g. 'os/exec/*_test.go'")
+	flags.Bool("tests", true, "Include tests")
+	flags.Bool("version", false, "Print version and exit")
+	flags.Bool("show-ignored", false, "Don't filter ignored problems")
+	flags.String("f", "text", "Output `format` (valid choices are 'text' and 'json')")
+
+	tags := build.Default.ReleaseTags
+	v := tags[len(tags)-1][2:]
+	version := new(versionFlag)
+	if err := version.Set(v); err != nil {
+		panic(fmt.Sprintf("internal error: %s", err))
+	}
+
+	flags.Var(version, "go", "Target Go `version` in the format '1.x'")
+	return flags
+}
+
+type CheckerConfig struct {
+	Checker     lint.Checker
+	ExitNonZero bool
+}
+
+func ProcessFlagSet(confs []CheckerConfig, fs *flag.FlagSet) {
+	tags := fs.Lookup("tags").Value.(flag.Getter).Get().(string)
+	ignore := fs.Lookup("ignore").Value.(flag.Getter).Get().(string)
+	tests := fs.Lookup("tests").Value.(flag.Getter).Get().(bool)
+	goVersion := fs.Lookup("go").Value.(flag.Getter).Get().(int)
+	format := fs.Lookup("f").Value.(flag.Getter).Get().(string)
+	printVersion := fs.Lookup("version").Value.(flag.Getter).Get().(bool)
+	showIgnored := fs.Lookup("show-ignored").Value.(flag.Getter).Get().(bool)
+
+	if printVersion {
+		version.Print()
+		os.Exit(0)
+	}
+
+	var cs []lint.Checker
+	for _, conf := range confs {
+		cs = append(cs, conf.Checker)
+	}
+	pss, err := Lint(cs, fs.Args(), &Options{
+		Tags:          strings.Fields(tags),
+		LintTests:     tests,
+		Ignores:       ignore,
+		GoVersion:     goVersion,
+		ReturnIgnored: showIgnored,
+	})
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+
+	var ps []lint.Problem
+	for _, p := range pss {
+		ps = append(ps, p...)
+	}
+
+	var f OutputFormatter
+	switch format {
+	case "text":
+		f = TextOutput{os.Stdout}
+	case "json":
+		f = JSONOutput{os.Stdout}
+	default:
+		fmt.Fprintf(os.Stderr, "unsupported output format %q\n", format)
+		os.Exit(2)
+	}
+
+	for _, p := range ps {
+		f.Format(p)
+	}
+	for i, p := range pss {
+		if len(p) != 0 && confs[i].ExitNonZero {
+			os.Exit(1)
+		}
+	}
+}
+
+type Options struct {
+	Tags          []string
+	LintTests     bool
+	Ignores       string
+	GoVersion     int
+	ReturnIgnored bool
+}
+
+func Lint(cs []lint.Checker, pkgs []string, opt *Options) ([][]lint.Problem, error) {
+	if opt == nil {
+		opt = &Options{}
+	}
+	ignores, err := parseIgnore(opt.Ignores)
+	if err != nil {
+		return nil, err
+	}
+	paths := gotool.ImportPaths(pkgs)
+	goFiles, err := resolveRelative(paths, opt.Tags)
+	if err != nil {
+		return nil, err
+	}
+	ctx := build.Default
+	ctx.BuildTags = opt.Tags
+	hadError := false
+	conf := &loader.Config{
+		Build:      &ctx,
+		ParserMode: parser.ParseComments,
+		ImportPkgs: map[string]bool{},
+		TypeChecker: types.Config{
+			Sizes: types.SizesFor(ctx.Compiler, ctx.GOARCH),
+			Error: func(err error) {
+				// Only print the first error found
+				if hadError {
+					return
+				}
+				hadError = true
+				fmt.Fprintln(os.Stderr, err)
+			},
+		},
+	}
+	if goFiles {
+		conf.CreateFromFilenames("adhoc", paths...)
+	} else {
+		for _, path := range paths {
+			conf.ImportPkgs[path] = opt.LintTests
+		}
+	}
+	lprog, err := conf.Load()
+	if err != nil {
+		return nil, err
+	}
+
+	var problems [][]lint.Problem
+	for _, c := range cs {
+		runner := &runner{
+			checker:       c,
+			tags:          opt.Tags,
+			ignores:       ignores,
+			version:       opt.GoVersion,
+			returnIgnored: opt.ReturnIgnored,
+		}
+		problems = append(problems, runner.lint(lprog, conf))
+	}
+	return problems, nil
+}
+
+func shortPath(path string) string {
+	cwd, err := os.Getwd()
+	if err != nil {
+		return path
+	}
+	if rel, err := filepath.Rel(cwd, path); err == nil && len(rel) < len(path) {
+		return rel
+	}
+	return path
+}
+
+func relativePositionString(pos token.Position) string {
+	s := shortPath(pos.Filename)
+	if pos.IsValid() {
+		if s != "" {
+			s += ":"
+		}
+		s += fmt.Sprintf("%d:%d", pos.Line, pos.Column)
+	}
+	if s == "" {
+		s = "-"
+	}
+	return s
+}
+
+func ProcessArgs(name string, cs []CheckerConfig, args []string) {
+	flags := FlagSet(name)
+	flags.Parse(args)
+
+	ProcessFlagSet(cs, flags)
+}
+
+func (runner *runner) lint(lprog *loader.Program, conf *loader.Config) []lint.Problem {
+	l := &lint.Linter{
+		Checker:       runner.checker,
+		Ignores:       runner.ignores,
+		GoVersion:     runner.version,
+		ReturnIgnored: runner.returnIgnored,
+	}
+	return l.Lint(lprog, conf)
+}

vendor/honnef.co/go/tools/simple/CONTRIBUTING.md

@@ -0,0 +1,15 @@
+# Contributing to gosimple
+
+## Before filing an issue:
+
+### Are you having trouble building gosimple?
+
+Check you have the latest version of its dependencies. Run
+```
+go get -u honnef.co/go/tools/simple
+```
+If you still have problems, consider searching for existing issues before filing a new issue.
+
+## Before sending a pull request:
+
+Have you understood the purpose of gosimple? Make sure to carefully read `README`.

vendor/honnef.co/go/tools/simple/lint17.go

@@ -0,0 +1,7 @@
+// +build !go1.8
+
+package simple
+
+import "go/types"
+
+var structsIdentical = types.Identical

vendor/honnef.co/go/tools/simple/lint18.go

@@ -0,0 +1,7 @@
+// +build go1.8
+
+package simple
+
+import "go/types"
+
+var structsIdentical = types.IdenticalIgnoreTags

vendor/honnef.co/go/tools/ssa/LICENSE

@@ -0,0 +1,28 @@
+Copyright (c) 2009 The Go Authors. All rights reserved.
+Copyright (c) 2016 Dominik Honnef. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/honnef.co/go/tools/ssa/blockopt.go

@@ -0,0 +1,195 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+// Simple block optimizations to simplify the control flow graph.
+
+// TODO(adonovan): opt: instead of creating several "unreachable" blocks
+// per function in the Builder, reuse a single one (e.g. at Blocks[1])
+// to reduce garbage.
+
+import (
+	"fmt"
+	"os"
+)
+
+// If true, perform sanity checking and show progress at each
+// successive iteration of optimizeBlocks.  Very verbose.
+const debugBlockOpt = false
+
+// markReachable sets Index=-1 for all blocks reachable from b.
+func markReachable(b *BasicBlock) {
+	b.Index = -1
+	for _, succ := range b.Succs {
+		if succ.Index == 0 {
+			markReachable(succ)
+		}
+	}
+}
+
+func DeleteUnreachableBlocks(f *Function) {
+	deleteUnreachableBlocks(f)
+}
+
+// deleteUnreachableBlocks marks all reachable blocks of f and
+// eliminates (nils) all others, including possibly cyclic subgraphs.
+//
+func deleteUnreachableBlocks(f *Function) {
+	const white, black = 0, -1
+	// We borrow b.Index temporarily as the mark bit.
+	for _, b := range f.Blocks {
+		b.Index = white
+	}
+	markReachable(f.Blocks[0])
+	if f.Recover != nil {
+		markReachable(f.Recover)
+	}
+	for i, b := range f.Blocks {
+		if b.Index == white {
+			for _, c := range b.Succs {
+				if c.Index == black {
+					c.removePred(b) // delete white->black edge
+				}
+			}
+			if debugBlockOpt {
+				fmt.Fprintln(os.Stderr, "unreachable", b)
+			}
+			f.Blocks[i] = nil // delete b
+		}
+	}
+	f.removeNilBlocks()
+}
+
+// jumpThreading attempts to apply simple jump-threading to block b,
+// in which a->b->c become a->c if b is just a Jump.
+// The result is true if the optimization was applied.
+//
+func jumpThreading(f *Function, b *BasicBlock) bool {
+	if b.Index == 0 {
+		return false // don't apply to entry block
+	}
+	if b.Instrs == nil {
+		return false
+	}
+	if _, ok := b.Instrs[0].(*Jump); !ok {
+		return false // not just a jump
+	}
+	c := b.Succs[0]
+	if c == b {
+		return false // don't apply to degenerate jump-to-self.
+	}
+	if c.hasPhi() {
+		return false // not sound without more effort
+	}
+	for j, a := range b.Preds {
+		a.replaceSucc(b, c)
+
+		// If a now has two edges to c, replace its degenerate If by Jump.
+		if len(a.Succs) == 2 && a.Succs[0] == c && a.Succs[1] == c {
+			jump := new(Jump)
+			jump.setBlock(a)
+			a.Instrs[len(a.Instrs)-1] = jump
+			a.Succs = a.Succs[:1]
+			c.removePred(b)
+		} else {
+			if j == 0 {
+				c.replacePred(b, a)
+			} else {
+				c.Preds = append(c.Preds, a)
+			}
+		}
+
+		if debugBlockOpt {
+			fmt.Fprintln(os.Stderr, "jumpThreading", a, b, c)
+		}
+	}
+	f.Blocks[b.Index] = nil // delete b
+	return true
+}
+
+// fuseBlocks attempts to apply the block fusion optimization to block
+// a, in which a->b becomes ab if len(a.Succs)==len(b.Preds)==1.
+// The result is true if the optimization was applied.
+//
+func fuseBlocks(f *Function, a *BasicBlock) bool {
+	if len(a.Succs) != 1 {
+		return false
+	}
+	b := a.Succs[0]
+	if len(b.Preds) != 1 {
+		return false
+	}
+
+	// Degenerate &&/|| ops may result in a straight-line CFG
+	// containing φ-nodes. (Ideally we'd replace such them with
+	// their sole operand but that requires Referrers, built later.)
+	if b.hasPhi() {
+		return false // not sound without further effort
+	}
+
+	// Eliminate jump at end of A, then copy all of B across.
+	a.Instrs = append(a.Instrs[:len(a.Instrs)-1], b.Instrs...)
+	for _, instr := range b.Instrs {
+		instr.setBlock(a)
+	}
+
+	// A inherits B's successors
+	a.Succs = append(a.succs2[:0], b.Succs...)
+
+	// Fix up Preds links of all successors of B.
+	for _, c := range b.Succs {
+		c.replacePred(b, a)
+	}
+
+	if debugBlockOpt {
+		fmt.Fprintln(os.Stderr, "fuseBlocks", a, b)
+	}
+
+	f.Blocks[b.Index] = nil // delete b
+	return true
+}
+
+func OptimizeBlocks(f *Function) {
+	optimizeBlocks(f)
+}
+
+// optimizeBlocks() performs some simple block optimizations on a
+// completed function: dead block elimination, block fusion, jump
+// threading.
+//
+func optimizeBlocks(f *Function) {
+	deleteUnreachableBlocks(f)
+
+	// Loop until no further progress.
+	changed := true
+	for changed {
+		changed = false
+
+		if debugBlockOpt {
+			f.WriteTo(os.Stderr)
+			mustSanityCheck(f, nil)
+		}
+
+		for _, b := range f.Blocks {
+			// f.Blocks will temporarily contain nils to indicate
+			// deleted blocks; we remove them at the end.
+			if b == nil {
+				continue
+			}
+
+			// Fuse blocks.  b->c becomes bc.
+			if fuseBlocks(f, b) {
+				changed = true
+			}
+
+			// a->b->c becomes a->c if b contains only a Jump.
+			if jumpThreading(f, b) {
+				changed = true
+				continue // (b was disconnected)
+			}
+		}
+	}
+	f.removeNilBlocks()
+}

vendor/honnef.co/go/tools/ssa/const.go

@@ -0,0 +1,169 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+// This file defines the Const SSA value type.
+
+import (
+	"fmt"
+	exact "go/constant"
+	"go/token"
+	"go/types"
+	"strconv"
+)
+
+// NewConst returns a new constant of the specified value and type.
+// val must be valid according to the specification of Const.Value.
+//
+func NewConst(val exact.Value, typ types.Type) *Const {
+	return &Const{typ, val}
+}
+
+// intConst returns an 'int' constant that evaluates to i.
+// (i is an int64 in case the host is narrower than the target.)
+func intConst(i int64) *Const {
+	return NewConst(exact.MakeInt64(i), tInt)
+}
+
+// nilConst returns a nil constant of the specified type, which may
+// be any reference type, including interfaces.
+//
+func nilConst(typ types.Type) *Const {
+	return NewConst(nil, typ)
+}
+
+// stringConst returns a 'string' constant that evaluates to s.
+func stringConst(s string) *Const {
+	return NewConst(exact.MakeString(s), tString)
+}
+
+// zeroConst returns a new "zero" constant of the specified type,
+// which must not be an array or struct type: the zero values of
+// aggregates are well-defined but cannot be represented by Const.
+//
+func zeroConst(t types.Type) *Const {
+	switch t := t.(type) {
+	case *types.Basic:
+		switch {
+		case t.Info()&types.IsBoolean != 0:
+			return NewConst(exact.MakeBool(false), t)
+		case t.Info()&types.IsNumeric != 0:
+			return NewConst(exact.MakeInt64(0), t)
+		case t.Info()&types.IsString != 0:
+			return NewConst(exact.MakeString(""), t)
+		case t.Kind() == types.UnsafePointer:
+			fallthrough
+		case t.Kind() == types.UntypedNil:
+			return nilConst(t)
+		default:
+			panic(fmt.Sprint("zeroConst for unexpected type:", t))
+		}
+	case *types.Pointer, *types.Slice, *types.Interface, *types.Chan, *types.Map, *types.Signature:
+		return nilConst(t)
+	case *types.Named:
+		return NewConst(zeroConst(t.Underlying()).Value, t)
+	case *types.Array, *types.Struct, *types.Tuple:
+		panic(fmt.Sprint("zeroConst applied to aggregate:", t))
+	}
+	panic(fmt.Sprint("zeroConst: unexpected ", t))
+}
+
+func (c *Const) RelString(from *types.Package) string {
+	var s string
+	if c.Value == nil {
+		s = "nil"
+	} else if c.Value.Kind() == exact.String {
+		s = exact.StringVal(c.Value)
+		const max = 20
+		// TODO(adonovan): don't cut a rune in half.
+		if len(s) > max {
+			s = s[:max-3] + "..." // abbreviate
+		}
+		s = strconv.Quote(s)
+	} else {
+		s = c.Value.String()
+	}
+	return s + ":" + relType(c.Type(), from)
+}
+
+func (c *Const) Name() string {
+	return c.RelString(nil)
+}
+
+func (c *Const) String() string {
+	return c.Name()
+}
+
+func (c *Const) Type() types.Type {
+	return c.typ
+}
+
+func (c *Const) Referrers() *[]Instruction {
+	return nil
+}
+
+func (c *Const) Parent() *Function { return nil }
+
+func (c *Const) Pos() token.Pos {
+	return token.NoPos
+}
+
+// IsNil returns true if this constant represents a typed or untyped nil value.
+func (c *Const) IsNil() bool {
+	return c.Value == nil
+}
+
+// TODO(adonovan): move everything below into honnef.co/go/tools/ssa/interp.
+
+// Int64 returns the numeric value of this constant truncated to fit
+// a signed 64-bit integer.
+//
+func (c *Const) Int64() int64 {
+	switch x := exact.ToInt(c.Value); x.Kind() {
+	case exact.Int:
+		if i, ok := exact.Int64Val(x); ok {
+			return i
+		}
+		return 0
+	case exact.Float:
+		f, _ := exact.Float64Val(x)
+		return int64(f)
+	}
+	panic(fmt.Sprintf("unexpected constant value: %T", c.Value))
+}
+
+// Uint64 returns the numeric value of this constant truncated to fit
+// an unsigned 64-bit integer.
+//
+func (c *Const) Uint64() uint64 {
+	switch x := exact.ToInt(c.Value); x.Kind() {
+	case exact.Int:
+		if u, ok := exact.Uint64Val(x); ok {
+			return u
+		}
+		return 0
+	case exact.Float:
+		f, _ := exact.Float64Val(x)
+		return uint64(f)
+	}
+	panic(fmt.Sprintf("unexpected constant value: %T", c.Value))
+}
+
+// Float64 returns the numeric value of this constant truncated to fit
+// a float64.
+//
+func (c *Const) Float64() float64 {
+	f, _ := exact.Float64Val(c.Value)
+	return f
+}
+
+// Complex128 returns the complex value of this constant truncated to
+// fit a complex128.
+//
+func (c *Const) Complex128() complex128 {
+	re, _ := exact.Float64Val(exact.Real(c.Value))
+	im, _ := exact.Float64Val(exact.Imag(c.Value))
+	return complex(re, im)
+}

vendor/honnef.co/go/tools/ssa/create.go

@@ -0,0 +1,263 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+// This file implements the CREATE phase of SSA construction.
+// See builder.go for explanation.
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+	"os"
+	"sync"
+
+	"golang.org/x/tools/go/types/typeutil"
+)
+
+// NewProgram returns a new SSA Program.
+//
+// mode controls diagnostics and checking during SSA construction.
+//
+func NewProgram(fset *token.FileSet, mode BuilderMode) *Program {
+	prog := &Program{
+		Fset:     fset,
+		imported: make(map[string]*Package),
+		packages: make(map[*types.Package]*Package),
+		thunks:   make(map[selectionKey]*Function),
+		bounds:   make(map[*types.Func]*Function),
+		mode:     mode,
+	}
+
+	h := typeutil.MakeHasher() // protected by methodsMu, in effect
+	prog.methodSets.SetHasher(h)
+	prog.canon.SetHasher(h)
+
+	return prog
+}
+
+// memberFromObject populates package pkg with a member for the
+// typechecker object obj.
+//
+// For objects from Go source code, syntax is the associated syntax
+// tree (for funcs and vars only); it will be used during the build
+// phase.
+//
+func memberFromObject(pkg *Package, obj types.Object, syntax ast.Node) {
+	name := obj.Name()
+	switch obj := obj.(type) {
+	case *types.Builtin:
+		if pkg.Pkg != types.Unsafe {
+			panic("unexpected builtin object: " + obj.String())
+		}
+
+	case *types.TypeName:
+		pkg.Members[name] = &Type{
+			object: obj,
+			pkg:    pkg,
+		}
+
+	case *types.Const:
+		c := &NamedConst{
+			object: obj,
+			Value:  NewConst(obj.Val(), obj.Type()),
+			pkg:    pkg,
+		}
+		pkg.values[obj] = c.Value
+		pkg.Members[name] = c
+
+	case *types.Var:
+		g := &Global{
+			Pkg:    pkg,
+			name:   name,
+			object: obj,
+			typ:    types.NewPointer(obj.Type()), // address
+			pos:    obj.Pos(),
+		}
+		pkg.values[obj] = g
+		pkg.Members[name] = g
+
+	case *types.Func:
+		sig := obj.Type().(*types.Signature)
+		if sig.Recv() == nil && name == "init" {
+			pkg.ninit++
+			name = fmt.Sprintf("init#%d", pkg.ninit)
+		}
+		fn := &Function{
+			name:      name,
+			object:    obj,
+			Signature: sig,
+			syntax:    syntax,
+			pos:       obj.Pos(),
+			Pkg:       pkg,
+			Prog:      pkg.Prog,
+		}
+		if syntax == nil {
+			fn.Synthetic = "loaded from gc object file"
+		}
+
+		pkg.values[obj] = fn
+		if sig.Recv() == nil {
+			pkg.Members[name] = fn // package-level function
+		}
+
+	default: // (incl. *types.Package)
+		panic("unexpected Object type: " + obj.String())
+	}
+}
+
+// membersFromDecl populates package pkg with members for each
+// typechecker object (var, func, const or type) associated with the
+// specified decl.
+//
+func membersFromDecl(pkg *Package, decl ast.Decl) {
+	switch decl := decl.(type) {
+	case *ast.GenDecl: // import, const, type or var
+		switch decl.Tok {
+		case token.CONST:
+			for _, spec := range decl.Specs {
+				for _, id := range spec.(*ast.ValueSpec).Names {
+					if !isBlankIdent(id) {
+						memberFromObject(pkg, pkg.info.Defs[id], nil)
+					}
+				}
+			}
+
+		case token.VAR:
+			for _, spec := range decl.Specs {
+				for _, id := range spec.(*ast.ValueSpec).Names {
+					if !isBlankIdent(id) {
+						memberFromObject(pkg, pkg.info.Defs[id], spec)
+					}
+				}
+			}
+
+		case token.TYPE:
+			for _, spec := range decl.Specs {
+				id := spec.(*ast.TypeSpec).Name
+				if !isBlankIdent(id) {
+					memberFromObject(pkg, pkg.info.Defs[id], nil)
+				}
+			}
+		}
+
+	case *ast.FuncDecl:
+		id := decl.Name
+		if !isBlankIdent(id) {
+			memberFromObject(pkg, pkg.info.Defs[id], decl)
+		}
+	}
+}
+
+// CreatePackage constructs and returns an SSA Package from the
+// specified type-checked, error-free file ASTs, and populates its
+// Members mapping.
+//
+// importable determines whether this package should be returned by a
+// subsequent call to ImportedPackage(pkg.Path()).
+//
+// The real work of building SSA form for each function is not done
+// until a subsequent call to Package.Build().
+//
+func (prog *Program) CreatePackage(pkg *types.Package, files []*ast.File, info *types.Info, importable bool) *Package {
+	p := &Package{
+		Prog:    prog,
+		Members: make(map[string]Member),
+		values:  make(map[types.Object]Value),
+		Pkg:     pkg,
+		info:    info,  // transient (CREATE and BUILD phases)
+		files:   files, // transient (CREATE and BUILD phases)
+	}
+
+	// Add init() function.
+	p.init = &Function{
+		name:      "init",
+		Signature: new(types.Signature),
+		Synthetic: "package initializer",
+		Pkg:       p,
+		Prog:      prog,
+	}
+	p.Members[p.init.name] = p.init
+
+	// CREATE phase.
+	// Allocate all package members: vars, funcs, consts and types.
+	if len(files) > 0 {
+		// Go source package.
+		for _, file := range files {
+			for _, decl := range file.Decls {
+				membersFromDecl(p, decl)
+			}
+		}
+	} else {
+		// GC-compiled binary package (or "unsafe")
+		// No code.
+		// No position information.
+		scope := p.Pkg.Scope()
+		for _, name := range scope.Names() {
+			obj := scope.Lookup(name)
+			memberFromObject(p, obj, nil)
+			if obj, ok := obj.(*types.TypeName); ok {
+				if named, ok := obj.Type().(*types.Named); ok {
+					for i, n := 0, named.NumMethods(); i < n; i++ {
+						memberFromObject(p, named.Method(i), nil)
+					}
+				}
+			}
+		}
+	}
+
+	if prog.mode&BareInits == 0 {
+		// Add initializer guard variable.
+		initguard := &Global{
+			Pkg:  p,
+			name: "init$guard",
+			typ:  types.NewPointer(tBool),
+		}
+		p.Members[initguard.Name()] = initguard
+	}
+
+	if prog.mode&GlobalDebug != 0 {
+		p.SetDebugMode(true)
+	}
+
+	if prog.mode&PrintPackages != 0 {
+		printMu.Lock()
+		p.WriteTo(os.Stdout)
+		printMu.Unlock()
+	}
+
+	if importable {
+		prog.imported[p.Pkg.Path()] = p
+	}
+	prog.packages[p.Pkg] = p
+
+	return p
+}
+
+// printMu serializes printing of Packages/Functions to stdout.
+var printMu sync.Mutex
+
+// AllPackages returns a new slice containing all packages in the
+// program prog in unspecified order.
+//
+func (prog *Program) AllPackages() []*Package {
+	pkgs := make([]*Package, 0, len(prog.packages))
+	for _, pkg := range prog.packages {
+		pkgs = append(pkgs, pkg)
+	}
+	return pkgs
+}
+
+// ImportedPackage returns the importable SSA Package whose import
+// path is path, or nil if no such SSA package has been created.
+//
+// Not all packages are importable.  For example, no import
+// declaration can resolve to the x_test package created by 'go test'
+// or the ad-hoc main package created 'go build foo.go'.
+//
+func (prog *Program) ImportedPackage(path string) *Package {
+	return prog.imported[path]
+}

vendor/honnef.co/go/tools/ssa/doc.go

@@ -0,0 +1,123 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package ssa defines a representation of the elements of Go programs
+// (packages, types, functions, variables and constants) using a
+// static single-assignment (SSA) form intermediate representation
+// (IR) for the bodies of functions.
+//
+// THIS INTERFACE IS EXPERIMENTAL AND IS LIKELY TO CHANGE.
+//
+// For an introduction to SSA form, see
+// http://en.wikipedia.org/wiki/Static_single_assignment_form.
+// This page provides a broader reading list:
+// http://www.dcs.gla.ac.uk/~jsinger/ssa.html.
+//
+// The level of abstraction of the SSA form is intentionally close to
+// the source language to facilitate construction of source analysis
+// tools.  It is not intended for machine code generation.
+//
+// All looping, branching and switching constructs are replaced with
+// unstructured control flow.  Higher-level control flow constructs
+// such as multi-way branch can be reconstructed as needed; see
+// ssautil.Switches() for an example.
+//
+// To construct an SSA-form program, call ssautil.CreateProgram on a
+// loader.Program, a set of type-checked packages created from
+// parsed Go source files.  The resulting ssa.Program contains all the
+// packages and their members, but SSA code is not created for
+// function bodies until a subsequent call to (*Package).Build.
+//
+// The builder initially builds a naive SSA form in which all local
+// variables are addresses of stack locations with explicit loads and
+// stores.  Registerisation of eligible locals and φ-node insertion
+// using dominance and dataflow are then performed as a second pass
+// called "lifting" to improve the accuracy and performance of
+// subsequent analyses; this pass can be skipped by setting the
+// NaiveForm builder flag.
+//
+// The primary interfaces of this package are:
+//
+//    - Member: a named member of a Go package.
+//    - Value: an expression that yields a value.
+//    - Instruction: a statement that consumes values and performs computation.
+//    - Node: a Value or Instruction (emphasizing its membership in the SSA value graph)
+//
+// A computation that yields a result implements both the Value and
+// Instruction interfaces.  The following table shows for each
+// concrete type which of these interfaces it implements.
+//
+//                      Value?          Instruction?    Member?
+//   *Alloc             ✔               ✔
+//   *BinOp             ✔               ✔
+//   *Builtin           ✔
+//   *Call              ✔               ✔
+//   *ChangeInterface   ✔               ✔
+//   *ChangeType        ✔               ✔
+//   *Const             ✔
+//   *Convert           ✔               ✔
+//   *DebugRef                          ✔
+//   *Defer                             ✔
+//   *Extract           ✔               ✔
+//   *Field             ✔               ✔
+//   *FieldAddr         ✔               ✔
+//   *FreeVar           ✔
+//   *Function          ✔                               ✔ (func)
+//   *Global            ✔                               ✔ (var)
+//   *Go                                ✔
+//   *If                                ✔
+//   *Index             ✔               ✔
+//   *IndexAddr         ✔               ✔
+//   *Jump                              ✔
+//   *Lookup            ✔               ✔
+//   *MakeChan          ✔               ✔
+//   *MakeClosure       ✔               ✔
+//   *MakeInterface     ✔               ✔
+//   *MakeMap           ✔               ✔
+//   *MakeSlice         ✔               ✔
+//   *MapUpdate                         ✔
+//   *NamedConst                                        ✔ (const)
+//   *Next              ✔               ✔
+//   *Panic                             ✔
+//   *Parameter         ✔
+//   *Phi               ✔               ✔
+//   *Range             ✔               ✔
+//   *Return                            ✔
+//   *RunDefers                         ✔
+//   *Select            ✔               ✔
+//   *Send                              ✔
+//   *Slice             ✔               ✔
+//   *Store                             ✔
+//   *Type                                              ✔ (type)
+//   *TypeAssert        ✔               ✔
+//   *UnOp              ✔               ✔
+//
+// Other key types in this package include: Program, Package, Function
+// and BasicBlock.
+//
+// The program representation constructed by this package is fully
+// resolved internally, i.e. it does not rely on the names of Values,
+// Packages, Functions, Types or BasicBlocks for the correct
+// interpretation of the program.  Only the identities of objects and
+// the topology of the SSA and type graphs are semantically
+// significant.  (There is one exception: Ids, used to identify field
+// and method names, contain strings.)  Avoidance of name-based
+// operations simplifies the implementation of subsequent passes and
+// can make them very efficient.  Many objects are nonetheless named
+// to aid in debugging, but it is not essential that the names be
+// either accurate or unambiguous.  The public API exposes a number of
+// name-based maps for client convenience.
+//
+// The ssa/ssautil package provides various utilities that depend only
+// on the public API of this package.
+//
+// TODO(adonovan): Consider the exceptional control-flow implications
+// of defer and recover().
+//
+// TODO(adonovan): write a how-to document for all the various cases
+// of trying to determine corresponding elements across the four
+// domains of source locations, ast.Nodes, types.Objects,
+// ssa.Values/Instructions.
+//
+package ssa // import "honnef.co/go/tools/ssa"

vendor/honnef.co/go/tools/ssa/dom.go

@@ -0,0 +1,341 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+// This file defines algorithms related to dominance.
+
+// Dominator tree construction ----------------------------------------
+//
+// We use the algorithm described in Lengauer & Tarjan. 1979.  A fast
+// algorithm for finding dominators in a flowgraph.
+// http://doi.acm.org/10.1145/357062.357071
+//
+// We also apply the optimizations to SLT described in Georgiadis et
+// al, Finding Dominators in Practice, JGAA 2006,
+// http://jgaa.info/accepted/2006/GeorgiadisTarjanWerneck2006.10.1.pdf
+// to avoid the need for buckets of size > 1.
+
+import (
+	"bytes"
+	"fmt"
+	"math/big"
+	"os"
+	"sort"
+)
+
+// Idom returns the block that immediately dominates b:
+// its parent in the dominator tree, if any.
+// Neither the entry node (b.Index==0) nor recover node
+// (b==b.Parent().Recover()) have a parent.
+//
+func (b *BasicBlock) Idom() *BasicBlock { return b.dom.idom }
+
+// Dominees returns the list of blocks that b immediately dominates:
+// its children in the dominator tree.
+//
+func (b *BasicBlock) Dominees() []*BasicBlock { return b.dom.children }
+
+// Dominates reports whether b dominates c.
+func (b *BasicBlock) Dominates(c *BasicBlock) bool {
+	return b.dom.pre <= c.dom.pre && c.dom.post <= b.dom.post
+}
+
+type byDomPreorder []*BasicBlock
+
+func (a byDomPreorder) Len() int           { return len(a) }
+func (a byDomPreorder) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+func (a byDomPreorder) Less(i, j int) bool { return a[i].dom.pre < a[j].dom.pre }
+
+// DomPreorder returns a new slice containing the blocks of f in
+// dominator tree preorder.
+//
+func (f *Function) DomPreorder() []*BasicBlock {
+	n := len(f.Blocks)
+	order := make(byDomPreorder, n, n)
+	copy(order, f.Blocks)
+	sort.Sort(order)
+	return order
+}
+
+// domInfo contains a BasicBlock's dominance information.
+type domInfo struct {
+	idom      *BasicBlock   // immediate dominator (parent in domtree)
+	children  []*BasicBlock // nodes immediately dominated by this one
+	pre, post int32         // pre- and post-order numbering within domtree
+}
+
+// ltState holds the working state for Lengauer-Tarjan algorithm
+// (during which domInfo.pre is repurposed for CFG DFS preorder number).
+type ltState struct {
+	// Each slice is indexed by b.Index.
+	sdom     []*BasicBlock // b's semidominator
+	parent   []*BasicBlock // b's parent in DFS traversal of CFG
+	ancestor []*BasicBlock // b's ancestor with least sdom
+}
+
+// dfs implements the depth-first search part of the LT algorithm.
+func (lt *ltState) dfs(v *BasicBlock, i int32, preorder []*BasicBlock) int32 {
+	preorder[i] = v
+	v.dom.pre = i // For now: DFS preorder of spanning tree of CFG
+	i++
+	lt.sdom[v.Index] = v
+	lt.link(nil, v)
+	for _, w := range v.Succs {
+		if lt.sdom[w.Index] == nil {
+			lt.parent[w.Index] = v
+			i = lt.dfs(w, i, preorder)
+		}
+	}
+	return i
+}
+
+// eval implements the EVAL part of the LT algorithm.
+func (lt *ltState) eval(v *BasicBlock) *BasicBlock {
+	// TODO(adonovan): opt: do path compression per simple LT.
+	u := v
+	for ; lt.ancestor[v.Index] != nil; v = lt.ancestor[v.Index] {
+		if lt.sdom[v.Index].dom.pre < lt.sdom[u.Index].dom.pre {
+			u = v
+		}
+	}
+	return u
+}
+
+// link implements the LINK part of the LT algorithm.
+func (lt *ltState) link(v, w *BasicBlock) {
+	lt.ancestor[w.Index] = v
+}
+
+// buildDomTree computes the dominator tree of f using the LT algorithm.
+// Precondition: all blocks are reachable (e.g. optimizeBlocks has been run).
+//
+func buildDomTree(f *Function) {
+	// The step numbers refer to the original LT paper; the
+	// reordering is due to Georgiadis.
+
+	// Clear any previous domInfo.
+	for _, b := range f.Blocks {
+		b.dom = domInfo{}
+	}
+
+	n := len(f.Blocks)
+	// Allocate space for 5 contiguous [n]*BasicBlock arrays:
+	// sdom, parent, ancestor, preorder, buckets.
+	space := make([]*BasicBlock, 5*n, 5*n)
+	lt := ltState{
+		sdom:     space[0:n],
+		parent:   space[n : 2*n],
+		ancestor: space[2*n : 3*n],
+	}
+
+	// Step 1.  Number vertices by depth-first preorder.
+	preorder := space[3*n : 4*n]
+	root := f.Blocks[0]
+	prenum := lt.dfs(root, 0, preorder)
+	recover := f.Recover
+	if recover != nil {
+		lt.dfs(recover, prenum, preorder)
+	}
+
+	buckets := space[4*n : 5*n]
+	copy(buckets, preorder)
+
+	// In reverse preorder...
+	for i := int32(n) - 1; i > 0; i-- {
+		w := preorder[i]
+
+		// Step 3. Implicitly define the immediate dominator of each node.
+		for v := buckets[i]; v != w; v = buckets[v.dom.pre] {
+			u := lt.eval(v)
+			if lt.sdom[u.Index].dom.pre < i {
+				v.dom.idom = u
+			} else {
+				v.dom.idom = w
+			}
+		}
+
+		// Step 2. Compute the semidominators of all nodes.
+		lt.sdom[w.Index] = lt.parent[w.Index]
+		for _, v := range w.Preds {
+			u := lt.eval(v)
+			if lt.sdom[u.Index].dom.pre < lt.sdom[w.Index].dom.pre {
+				lt.sdom[w.Index] = lt.sdom[u.Index]
+			}
+		}
+
+		lt.link(lt.parent[w.Index], w)
+
+		if lt.parent[w.Index] == lt.sdom[w.Index] {
+			w.dom.idom = lt.parent[w.Index]
+		} else {
+			buckets[i] = buckets[lt.sdom[w.Index].dom.pre]
+			buckets[lt.sdom[w.Index].dom.pre] = w
+		}
+	}
+
+	// The final 'Step 3' is now outside the loop.
+	for v := buckets[0]; v != root; v = buckets[v.dom.pre] {
+		v.dom.idom = root
+	}
+
+	// Step 4. Explicitly define the immediate dominator of each
+	// node, in preorder.
+	for _, w := range preorder[1:] {
+		if w == root || w == recover {
+			w.dom.idom = nil
+		} else {
+			if w.dom.idom != lt.sdom[w.Index] {
+				w.dom.idom = w.dom.idom.dom.idom
+			}
+			// Calculate Children relation as inverse of Idom.
+			w.dom.idom.dom.children = append(w.dom.idom.dom.children, w)
+		}
+	}
+
+	pre, post := numberDomTree(root, 0, 0)
+	if recover != nil {
+		numberDomTree(recover, pre, post)
+	}
+
+	// printDomTreeDot(os.Stderr, f)        // debugging
+	// printDomTreeText(os.Stderr, root, 0) // debugging
+
+	if f.Prog.mode&SanityCheckFunctions != 0 {
+		sanityCheckDomTree(f)
+	}
+}
+
+// numberDomTree sets the pre- and post-order numbers of a depth-first
+// traversal of the dominator tree rooted at v.  These are used to
+// answer dominance queries in constant time.
+//
+func numberDomTree(v *BasicBlock, pre, post int32) (int32, int32) {
+	v.dom.pre = pre
+	pre++
+	for _, child := range v.dom.children {
+		pre, post = numberDomTree(child, pre, post)
+	}
+	v.dom.post = post
+	post++
+	return pre, post
+}
+
+// Testing utilities ----------------------------------------
+
+// sanityCheckDomTree checks the correctness of the dominator tree
+// computed by the LT algorithm by comparing against the dominance
+// relation computed by a naive Kildall-style forward dataflow
+// analysis (Algorithm 10.16 from the "Dragon" book).
+//
+func sanityCheckDomTree(f *Function) {
+	n := len(f.Blocks)
+
+	// D[i] is the set of blocks that dominate f.Blocks[i],
+	// represented as a bit-set of block indices.
+	D := make([]big.Int, n)
+
+	one := big.NewInt(1)
+
+	// all is the set of all blocks; constant.
+	var all big.Int
+	all.Set(one).Lsh(&all, uint(n)).Sub(&all, one)
+
+	// Initialization.
+	for i, b := range f.Blocks {
+		if i == 0 || b == f.Recover {
+			// A root is dominated only by itself.
+			D[i].SetBit(&D[0], 0, 1)
+		} else {
+			// All other blocks are (initially) dominated
+			// by every block.
+			D[i].Set(&all)
+		}
+	}
+
+	// Iteration until fixed point.
+	for changed := true; changed; {
+		changed = false
+		for i, b := range f.Blocks {
+			if i == 0 || b == f.Recover {
+				continue
+			}
+			// Compute intersection across predecessors.
+			var x big.Int
+			x.Set(&all)
+			for _, pred := range b.Preds {
+				x.And(&x, &D[pred.Index])
+			}
+			x.SetBit(&x, i, 1) // a block always dominates itself.
+			if D[i].Cmp(&x) != 0 {
+				D[i].Set(&x)
+				changed = true
+			}
+		}
+	}
+
+	// Check the entire relation.  O(n^2).
+	// The Recover block (if any) must be treated specially so we skip it.
+	ok := true
+	for i := 0; i < n; i++ {
+		for j := 0; j < n; j++ {
+			b, c := f.Blocks[i], f.Blocks[j]
+			if c == f.Recover {
+				continue
+			}
+			actual := b.Dominates(c)
+			expected := D[j].Bit(i) == 1
+			if actual != expected {
+				fmt.Fprintf(os.Stderr, "dominates(%s, %s)==%t, want %t\n", b, c, actual, expected)
+				ok = false
+			}
+		}
+	}
+
+	preorder := f.DomPreorder()
+	for _, b := range f.Blocks {
+		if got := preorder[b.dom.pre]; got != b {
+			fmt.Fprintf(os.Stderr, "preorder[%d]==%s, want %s\n", b.dom.pre, got, b)
+			ok = false
+		}
+	}
+
+	if !ok {
+		panic("sanityCheckDomTree failed for " + f.String())
+	}
+
+}
+
+// Printing functions ----------------------------------------
+
+// printDomTree prints the dominator tree as text, using indentation.
+func printDomTreeText(buf *bytes.Buffer, v *BasicBlock, indent int) {
+	fmt.Fprintf(buf, "%*s%s\n", 4*indent, "", v)
+	for _, child := range v.dom.children {
+		printDomTreeText(buf, child, indent+1)
+	}
+}
+
+// printDomTreeDot prints the dominator tree of f in AT&T GraphViz
+// (.dot) format.
+func printDomTreeDot(buf *bytes.Buffer, f *Function) {
+	fmt.Fprintln(buf, "//", f)
+	fmt.Fprintln(buf, "digraph domtree {")
+	for i, b := range f.Blocks {
+		v := b.dom
+		fmt.Fprintf(buf, "\tn%d [label=\"%s (%d, %d)\",shape=\"rectangle\"];\n", v.pre, b, v.pre, v.post)
+		// TODO(adonovan): improve appearance of edges
+		// belonging to both dominator tree and CFG.
+
+		// Dominator tree edge.
+		if i != 0 {
+			fmt.Fprintf(buf, "\tn%d -> n%d [style=\"solid\",weight=100];\n", v.idom.dom.pre, v.pre)
+		}
+		// CFG edges.
+		for _, pred := range b.Preds {
+			fmt.Fprintf(buf, "\tn%d -> n%d [style=\"dotted\",weight=0];\n", pred.dom.pre, v.pre)
+		}
+	}
+	fmt.Fprintln(buf, "}")
+}

vendor/honnef.co/go/tools/ssa/emit.go

@@ -0,0 +1,468 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+// Helpers for emitting SSA instructions.
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+)
+
+// emitNew emits to f a new (heap Alloc) instruction allocating an
+// object of type typ.  pos is the optional source location.
+//
+func emitNew(f *Function, typ types.Type, pos token.Pos) *Alloc {
+	v := &Alloc{Heap: true}
+	v.setType(types.NewPointer(typ))
+	v.setPos(pos)
+	f.emit(v)
+	return v
+}
+
+// emitLoad emits to f an instruction to load the address addr into a
+// new temporary, and returns the value so defined.
+//
+func emitLoad(f *Function, addr Value) *UnOp {
+	v := &UnOp{Op: token.MUL, X: addr}
+	v.setType(deref(addr.Type()))
+	f.emit(v)
+	return v
+}
+
+// emitDebugRef emits to f a DebugRef pseudo-instruction associating
+// expression e with value v.
+//
+func emitDebugRef(f *Function, e ast.Expr, v Value, isAddr bool) {
+	if !f.debugInfo() {
+		return // debugging not enabled
+	}
+	if v == nil || e == nil {
+		panic("nil")
+	}
+	var obj types.Object
+	e = unparen(e)
+	if id, ok := e.(*ast.Ident); ok {
+		if isBlankIdent(id) {
+			return
+		}
+		obj = f.Pkg.objectOf(id)
+		switch obj.(type) {
+		case *types.Nil, *types.Const, *types.Builtin:
+			return
+		}
+	}
+	f.emit(&DebugRef{
+		X:      v,
+		Expr:   e,
+		IsAddr: isAddr,
+		object: obj,
+	})
+}
+
+// emitArith emits to f code to compute the binary operation op(x, y)
+// where op is an eager shift, logical or arithmetic operation.
+// (Use emitCompare() for comparisons and Builder.logicalBinop() for
+// non-eager operations.)
+//
+func emitArith(f *Function, op token.Token, x, y Value, t types.Type, pos token.Pos) Value {
+	switch op {
+	case token.SHL, token.SHR:
+		x = emitConv(f, x, t)
+		// y may be signed or an 'untyped' constant.
+		// TODO(adonovan): whence signed values?
+		if b, ok := y.Type().Underlying().(*types.Basic); ok && b.Info()&types.IsUnsigned == 0 {
+			y = emitConv(f, y, types.Typ[types.Uint64])
+		}
+
+	case token.ADD, token.SUB, token.MUL, token.QUO, token.REM, token.AND, token.OR, token.XOR, token.AND_NOT:
+		x = emitConv(f, x, t)
+		y = emitConv(f, y, t)
+
+	default:
+		panic("illegal op in emitArith: " + op.String())
+
+	}
+	v := &BinOp{
+		Op: op,
+		X:  x,
+		Y:  y,
+	}
+	v.setPos(pos)
+	v.setType(t)
+	return f.emit(v)
+}
+
+// emitCompare emits to f code compute the boolean result of
+// comparison comparison 'x op y'.
+//
+func emitCompare(f *Function, op token.Token, x, y Value, pos token.Pos) Value {
+	xt := x.Type().Underlying()
+	yt := y.Type().Underlying()
+
+	// Special case to optimise a tagless SwitchStmt so that
+	// these are equivalent
+	//   switch { case e: ...}
+	//   switch true { case e: ... }
+	//   if e==true { ... }
+	// even in the case when e's type is an interface.
+	// TODO(adonovan): opt: generalise to x==true, false!=y, etc.
+	if x == vTrue && op == token.EQL {
+		if yt, ok := yt.(*types.Basic); ok && yt.Info()&types.IsBoolean != 0 {
+			return y
+		}
+	}
+
+	if types.Identical(xt, yt) {
+		// no conversion necessary
+	} else if _, ok := xt.(*types.Interface); ok {
+		y = emitConv(f, y, x.Type())
+	} else if _, ok := yt.(*types.Interface); ok {
+		x = emitConv(f, x, y.Type())
+	} else if _, ok := x.(*Const); ok {
+		x = emitConv(f, x, y.Type())
+	} else if _, ok := y.(*Const); ok {
+		y = emitConv(f, y, x.Type())
+	} else {
+		// other cases, e.g. channels.  No-op.
+	}
+
+	v := &BinOp{
+		Op: op,
+		X:  x,
+		Y:  y,
+	}
+	v.setPos(pos)
+	v.setType(tBool)
+	return f.emit(v)
+}
+
+// isValuePreserving returns true if a conversion from ut_src to
+// ut_dst is value-preserving, i.e. just a change of type.
+// Precondition: neither argument is a named type.
+//
+func isValuePreserving(ut_src, ut_dst types.Type) bool {
+	// Identical underlying types?
+	if structTypesIdentical(ut_dst, ut_src) {
+		return true
+	}
+
+	switch ut_dst.(type) {
+	case *types.Chan:
+		// Conversion between channel types?
+		_, ok := ut_src.(*types.Chan)
+		return ok
+
+	case *types.Pointer:
+		// Conversion between pointers with identical base types?
+		_, ok := ut_src.(*types.Pointer)
+		return ok
+	}
+	return false
+}
+
+// emitConv emits to f code to convert Value val to exactly type typ,
+// and returns the converted value.  Implicit conversions are required
+// by language assignability rules in assignments, parameter passing,
+// etc.  Conversions cannot fail dynamically.
+//
+func emitConv(f *Function, val Value, typ types.Type) Value {
+	t_src := val.Type()
+
+	// Identical types?  Conversion is a no-op.
+	if types.Identical(t_src, typ) {
+		return val
+	}
+
+	ut_dst := typ.Underlying()
+	ut_src := t_src.Underlying()
+
+	// Just a change of type, but not value or representation?
+	if isValuePreserving(ut_src, ut_dst) {
+		c := &ChangeType{X: val}
+		c.setType(typ)
+		return f.emit(c)
+	}
+
+	// Conversion to, or construction of a value of, an interface type?
+	if _, ok := ut_dst.(*types.Interface); ok {
+		// Assignment from one interface type to another?
+		if _, ok := ut_src.(*types.Interface); ok {
+			c := &ChangeInterface{X: val}
+			c.setType(typ)
+			return f.emit(c)
+		}
+
+		// Untyped nil constant?  Return interface-typed nil constant.
+		if ut_src == tUntypedNil {
+			return nilConst(typ)
+		}
+
+		// Convert (non-nil) "untyped" literals to their default type.
+		if t, ok := ut_src.(*types.Basic); ok && t.Info()&types.IsUntyped != 0 {
+			val = emitConv(f, val, DefaultType(ut_src))
+		}
+
+		f.Pkg.Prog.needMethodsOf(val.Type())
+		mi := &MakeInterface{X: val}
+		mi.setType(typ)
+		return f.emit(mi)
+	}
+
+	// Conversion of a compile-time constant value?
+	if c, ok := val.(*Const); ok {
+		if _, ok := ut_dst.(*types.Basic); ok || c.IsNil() {
+			// Conversion of a compile-time constant to
+			// another constant type results in a new
+			// constant of the destination type and
+			// (initially) the same abstract value.
+			// We don't truncate the value yet.
+			return NewConst(c.Value, typ)
+		}
+
+		// We're converting from constant to non-constant type,
+		// e.g. string -> []byte/[]rune.
+	}
+
+	// A representation-changing conversion?
+	// At least one of {ut_src,ut_dst} must be *Basic.
+	// (The other may be []byte or []rune.)
+	_, ok1 := ut_src.(*types.Basic)
+	_, ok2 := ut_dst.(*types.Basic)
+	if ok1 || ok2 {
+		c := &Convert{X: val}
+		c.setType(typ)
+		return f.emit(c)
+	}
+
+	panic(fmt.Sprintf("in %s: cannot convert %s (%s) to %s", f, val, val.Type(), typ))
+}
+
+// emitStore emits to f an instruction to store value val at location
+// addr, applying implicit conversions as required by assignability rules.
+//
+func emitStore(f *Function, addr, val Value, pos token.Pos) *Store {
+	s := &Store{
+		Addr: addr,
+		Val:  emitConv(f, val, deref(addr.Type())),
+		pos:  pos,
+	}
+	f.emit(s)
+	return s
+}
+
+// emitJump emits to f a jump to target, and updates the control-flow graph.
+// Postcondition: f.currentBlock is nil.
+//
+func emitJump(f *Function, target *BasicBlock) {
+	b := f.currentBlock
+	b.emit(new(Jump))
+	addEdge(b, target)
+	f.currentBlock = nil
+}
+
+// emitIf emits to f a conditional jump to tblock or fblock based on
+// cond, and updates the control-flow graph.
+// Postcondition: f.currentBlock is nil.
+//
+func emitIf(f *Function, cond Value, tblock, fblock *BasicBlock) {
+	b := f.currentBlock
+	b.emit(&If{Cond: cond})
+	addEdge(b, tblock)
+	addEdge(b, fblock)
+	f.currentBlock = nil
+}
+
+// emitExtract emits to f an instruction to extract the index'th
+// component of tuple.  It returns the extracted value.
+//
+func emitExtract(f *Function, tuple Value, index int) Value {
+	e := &Extract{Tuple: tuple, Index: index}
+	e.setType(tuple.Type().(*types.Tuple).At(index).Type())
+	return f.emit(e)
+}
+
+// emitTypeAssert emits to f a type assertion value := x.(t) and
+// returns the value.  x.Type() must be an interface.
+//
+func emitTypeAssert(f *Function, x Value, t types.Type, pos token.Pos) Value {
+	a := &TypeAssert{X: x, AssertedType: t}
+	a.setPos(pos)
+	a.setType(t)
+	return f.emit(a)
+}
+
+// emitTypeTest emits to f a type test value,ok := x.(t) and returns
+// a (value, ok) tuple.  x.Type() must be an interface.
+//
+func emitTypeTest(f *Function, x Value, t types.Type, pos token.Pos) Value {
+	a := &TypeAssert{
+		X:            x,
+		AssertedType: t,
+		CommaOk:      true,
+	}
+	a.setPos(pos)
+	a.setType(types.NewTuple(
+		newVar("value", t),
+		varOk,
+	))
+	return f.emit(a)
+}
+
+// emitTailCall emits to f a function call in tail position.  The
+// caller is responsible for all fields of 'call' except its type.
+// Intended for wrapper methods.
+// Precondition: f does/will not use deferred procedure calls.
+// Postcondition: f.currentBlock is nil.
+//
+func emitTailCall(f *Function, call *Call) {
+	tresults := f.Signature.Results()
+	nr := tresults.Len()
+	if nr == 1 {
+		call.typ = tresults.At(0).Type()
+	} else {
+		call.typ = tresults
+	}
+	tuple := f.emit(call)
+	var ret Return
+	switch nr {
+	case 0:
+		// no-op
+	case 1:
+		ret.Results = []Value{tuple}
+	default:
+		for i := 0; i < nr; i++ {
+			v := emitExtract(f, tuple, i)
+			// TODO(adonovan): in principle, this is required:
+			//   v = emitConv(f, o.Type, f.Signature.Results[i].Type)
+			// but in practice emitTailCall is only used when
+			// the types exactly match.
+			ret.Results = append(ret.Results, v)
+		}
+	}
+	f.emit(&ret)
+	f.currentBlock = nil
+}
+
+// emitImplicitSelections emits to f code to apply the sequence of
+// implicit field selections specified by indices to base value v, and
+// returns the selected value.
+//
+// If v is the address of a struct, the result will be the address of
+// a field; if it is the value of a struct, the result will be the
+// value of a field.
+//
+func emitImplicitSelections(f *Function, v Value, indices []int) Value {
+	for _, index := range indices {
+		fld := deref(v.Type()).Underlying().(*types.Struct).Field(index)
+
+		if isPointer(v.Type()) {
+			instr := &FieldAddr{
+				X:     v,
+				Field: index,
+			}
+			instr.setType(types.NewPointer(fld.Type()))
+			v = f.emit(instr)
+			// Load the field's value iff indirectly embedded.
+			if isPointer(fld.Type()) {
+				v = emitLoad(f, v)
+			}
+		} else {
+			instr := &Field{
+				X:     v,
+				Field: index,
+			}
+			instr.setType(fld.Type())
+			v = f.emit(instr)
+		}
+	}
+	return v
+}
+
+// emitFieldSelection emits to f code to select the index'th field of v.
+//
+// If wantAddr, the input must be a pointer-to-struct and the result
+// will be the field's address; otherwise the result will be the
+// field's value.
+// Ident id is used for position and debug info.
+//
+func emitFieldSelection(f *Function, v Value, index int, wantAddr bool, id *ast.Ident) Value {
+	fld := deref(v.Type()).Underlying().(*types.Struct).Field(index)
+	if isPointer(v.Type()) {
+		instr := &FieldAddr{
+			X:     v,
+			Field: index,
+		}
+		instr.setPos(id.Pos())
+		instr.setType(types.NewPointer(fld.Type()))
+		v = f.emit(instr)
+		// Load the field's value iff we don't want its address.
+		if !wantAddr {
+			v = emitLoad(f, v)
+		}
+	} else {
+		instr := &Field{
+			X:     v,
+			Field: index,
+		}
+		instr.setPos(id.Pos())
+		instr.setType(fld.Type())
+		v = f.emit(instr)
+	}
+	emitDebugRef(f, id, v, wantAddr)
+	return v
+}
+
+// zeroValue emits to f code to produce a zero value of type t,
+// and returns it.
+//
+func zeroValue(f *Function, t types.Type) Value {
+	switch t.Underlying().(type) {
+	case *types.Struct, *types.Array:
+		return emitLoad(f, f.addLocal(t, token.NoPos))
+	default:
+		return zeroConst(t)
+	}
+}
+
+// createRecoverBlock emits to f a block of code to return after a
+// recovered panic, and sets f.Recover to it.
+//
+// If f's result parameters are named, the code loads and returns
+// their current values, otherwise it returns the zero values of their
+// type.
+//
+// Idempotent.
+//
+func createRecoverBlock(f *Function) {
+	if f.Recover != nil {
+		return // already created
+	}
+	saved := f.currentBlock
+
+	f.Recover = f.newBasicBlock("recover")
+	f.currentBlock = f.Recover
+
+	var results []Value
+	if f.namedResults != nil {
+		// Reload NRPs to form value tuple.
+		for _, r := range f.namedResults {
+			results = append(results, emitLoad(f, r))
+		}
+	} else {
+		R := f.Signature.Results()
+		for i, n := 0, R.Len(); i < n; i++ {
+			T := R.At(i).Type()
+
+			// Return zero value of each result type.
+			results = append(results, zeroValue(f, T))
+		}
+	}
+	f.emit(&Return{Results: results})
+
+	f.currentBlock = saved
+}

vendor/honnef.co/go/tools/ssa/func.go

@@ -0,0 +1,701 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+// This file implements the Function and BasicBlock types.
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+	"io"
+	"os"
+	"strings"
+)
+
+// addEdge adds a control-flow graph edge from from to to.
+func addEdge(from, to *BasicBlock) {
+	from.Succs = append(from.Succs, to)
+	to.Preds = append(to.Preds, from)
+}
+
+// Parent returns the function that contains block b.
+func (b *BasicBlock) Parent() *Function { return b.parent }
+
+// String returns a human-readable label of this block.
+// It is not guaranteed unique within the function.
+//
+func (b *BasicBlock) String() string {
+	return fmt.Sprintf("%d", b.Index)
+}
+
+// emit appends an instruction to the current basic block.
+// If the instruction defines a Value, it is returned.
+//
+func (b *BasicBlock) emit(i Instruction) Value {
+	i.setBlock(b)
+	b.Instrs = append(b.Instrs, i)
+	v, _ := i.(Value)
+	return v
+}
+
+// predIndex returns the i such that b.Preds[i] == c or panics if
+// there is none.
+func (b *BasicBlock) predIndex(c *BasicBlock) int {
+	for i, pred := range b.Preds {
+		if pred == c {
+			return i
+		}
+	}
+	panic(fmt.Sprintf("no edge %s -> %s", c, b))
+}
+
+// hasPhi returns true if b.Instrs contains φ-nodes.
+func (b *BasicBlock) hasPhi() bool {
+	_, ok := b.Instrs[0].(*Phi)
+	return ok
+}
+
+func (b *BasicBlock) Phis() []Instruction {
+	return b.phis()
+}
+
+// phis returns the prefix of b.Instrs containing all the block's φ-nodes.
+func (b *BasicBlock) phis() []Instruction {
+	for i, instr := range b.Instrs {
+		if _, ok := instr.(*Phi); !ok {
+			return b.Instrs[:i]
+		}
+	}
+	return nil // unreachable in well-formed blocks
+}
+
+// replacePred replaces all occurrences of p in b's predecessor list with q.
+// Ordinarily there should be at most one.
+//
+func (b *BasicBlock) replacePred(p, q *BasicBlock) {
+	for i, pred := range b.Preds {
+		if pred == p {
+			b.Preds[i] = q
+		}
+	}
+}
+
+// replaceSucc replaces all occurrences of p in b's successor list with q.
+// Ordinarily there should be at most one.
+//
+func (b *BasicBlock) replaceSucc(p, q *BasicBlock) {
+	for i, succ := range b.Succs {
+		if succ == p {
+			b.Succs[i] = q
+		}
+	}
+}
+
+func (b *BasicBlock) RemovePred(p *BasicBlock) {
+	b.removePred(p)
+}
+
+// removePred removes all occurrences of p in b's
+// predecessor list and φ-nodes.
+// Ordinarily there should be at most one.
+//
+func (b *BasicBlock) removePred(p *BasicBlock) {
+	phis := b.phis()
+
+	// We must preserve edge order for φ-nodes.
+	j := 0
+	for i, pred := range b.Preds {
+		if pred != p {
+			b.Preds[j] = b.Preds[i]
+			// Strike out φ-edge too.
+			for _, instr := range phis {
+				phi := instr.(*Phi)
+				phi.Edges[j] = phi.Edges[i]
+			}
+			j++
+		}
+	}
+	// Nil out b.Preds[j:] and φ-edges[j:] to aid GC.
+	for i := j; i < len(b.Preds); i++ {
+		b.Preds[i] = nil
+		for _, instr := range phis {
+			instr.(*Phi).Edges[i] = nil
+		}
+	}
+	b.Preds = b.Preds[:j]
+	for _, instr := range phis {
+		phi := instr.(*Phi)
+		phi.Edges = phi.Edges[:j]
+	}
+}
+
+// Destinations associated with unlabelled for/switch/select stmts.
+// We push/pop one of these as we enter/leave each construct and for
+// each BranchStmt we scan for the innermost target of the right type.
+//
+type targets struct {
+	tail         *targets // rest of stack
+	_break       *BasicBlock
+	_continue    *BasicBlock
+	_fallthrough *BasicBlock
+}
+
+// Destinations associated with a labelled block.
+// We populate these as labels are encountered in forward gotos or
+// labelled statements.
+//
+type lblock struct {
+	_goto     *BasicBlock
+	_break    *BasicBlock
+	_continue *BasicBlock
+}
+
+// labelledBlock returns the branch target associated with the
+// specified label, creating it if needed.
+//
+func (f *Function) labelledBlock(label *ast.Ident) *lblock {
+	lb := f.lblocks[label.Obj]
+	if lb == nil {
+		lb = &lblock{_goto: f.newBasicBlock(label.Name)}
+		if f.lblocks == nil {
+			f.lblocks = make(map[*ast.Object]*lblock)
+		}
+		f.lblocks[label.Obj] = lb
+	}
+	return lb
+}
+
+// addParam adds a (non-escaping) parameter to f.Params of the
+// specified name, type and source position.
+//
+func (f *Function) addParam(name string, typ types.Type, pos token.Pos) *Parameter {
+	v := &Parameter{
+		name:   name,
+		typ:    typ,
+		pos:    pos,
+		parent: f,
+	}
+	f.Params = append(f.Params, v)
+	return v
+}
+
+func (f *Function) addParamObj(obj types.Object) *Parameter {
+	name := obj.Name()
+	if name == "" {
+		name = fmt.Sprintf("arg%d", len(f.Params))
+	}
+	param := f.addParam(name, obj.Type(), obj.Pos())
+	param.object = obj
+	return param
+}
+
+// addSpilledParam declares a parameter that is pre-spilled to the
+// stack; the function body will load/store the spilled location.
+// Subsequent lifting will eliminate spills where possible.
+//
+func (f *Function) addSpilledParam(obj types.Object) {
+	param := f.addParamObj(obj)
+	spill := &Alloc{Comment: obj.Name()}
+	spill.setType(types.NewPointer(obj.Type()))
+	spill.setPos(obj.Pos())
+	f.objects[obj] = spill
+	f.Locals = append(f.Locals, spill)
+	f.emit(spill)
+	f.emit(&Store{Addr: spill, Val: param})
+}
+
+// startBody initializes the function prior to generating SSA code for its body.
+// Precondition: f.Type() already set.
+//
+func (f *Function) startBody() {
+	f.currentBlock = f.newBasicBlock("entry")
+	f.objects = make(map[types.Object]Value) // needed for some synthetics, e.g. init
+}
+
+// createSyntacticParams populates f.Params and generates code (spills
+// and named result locals) for all the parameters declared in the
+// syntax.  In addition it populates the f.objects mapping.
+//
+// Preconditions:
+// f.startBody() was called.
+// Postcondition:
+// len(f.Params) == len(f.Signature.Params) + (f.Signature.Recv() ? 1 : 0)
+//
+func (f *Function) createSyntacticParams(recv *ast.FieldList, functype *ast.FuncType) {
+	// Receiver (at most one inner iteration).
+	if recv != nil {
+		for _, field := range recv.List {
+			for _, n := range field.Names {
+				f.addSpilledParam(f.Pkg.info.Defs[n])
+			}
+			// Anonymous receiver?  No need to spill.
+			if field.Names == nil {
+				f.addParamObj(f.Signature.Recv())
+			}
+		}
+	}
+
+	// Parameters.
+	if functype.Params != nil {
+		n := len(f.Params) // 1 if has recv, 0 otherwise
+		for _, field := range functype.Params.List {
+			for _, n := range field.Names {
+				f.addSpilledParam(f.Pkg.info.Defs[n])
+			}
+			// Anonymous parameter?  No need to spill.
+			if field.Names == nil {
+				f.addParamObj(f.Signature.Params().At(len(f.Params) - n))
+			}
+		}
+	}
+
+	// Named results.
+	if functype.Results != nil {
+		for _, field := range functype.Results.List {
+			// Implicit "var" decl of locals for named results.
+			for _, n := range field.Names {
+				f.namedResults = append(f.namedResults, f.addLocalForIdent(n))
+			}
+		}
+	}
+}
+
+// numberRegisters assigns numbers to all SSA registers
+// (value-defining Instructions) in f, to aid debugging.
+// (Non-Instruction Values are named at construction.)
+//
+func numberRegisters(f *Function) {
+	v := 0
+	for _, b := range f.Blocks {
+		for _, instr := range b.Instrs {
+			switch instr.(type) {
+			case Value:
+				instr.(interface {
+					setNum(int)
+				}).setNum(v)
+				v++
+			}
+		}
+	}
+}
+
+// buildReferrers populates the def/use information in all non-nil
+// Value.Referrers slice.
+// Precondition: all such slices are initially empty.
+func buildReferrers(f *Function) {
+	var rands []*Value
+	for _, b := range f.Blocks {
+		for _, instr := range b.Instrs {
+			rands = instr.Operands(rands[:0]) // recycle storage
+			for _, rand := range rands {
+				if r := *rand; r != nil {
+					if ref := r.Referrers(); ref != nil {
+						*ref = append(*ref, instr)
+					}
+				}
+			}
+		}
+	}
+}
+
+// finishBody() finalizes the function after SSA code generation of its body.
+func (f *Function) finishBody() {
+	f.objects = nil
+	f.currentBlock = nil
+	f.lblocks = nil
+
+	// Don't pin the AST in memory (except in debug mode).
+	if n := f.syntax; n != nil && !f.debugInfo() {
+		f.syntax = extentNode{n.Pos(), n.End()}
+	}
+
+	// Remove from f.Locals any Allocs that escape to the heap.
+	j := 0
+	for _, l := range f.Locals {
+		if !l.Heap {
+			f.Locals[j] = l
+			j++
+		}
+	}
+	// Nil out f.Locals[j:] to aid GC.
+	for i := j; i < len(f.Locals); i++ {
+		f.Locals[i] = nil
+	}
+	f.Locals = f.Locals[:j]
+
+	optimizeBlocks(f)
+
+	buildReferrers(f)
+
+	buildDomTree(f)
+
+	if f.Prog.mode&NaiveForm == 0 {
+		// For debugging pre-state of lifting pass:
+		// numberRegisters(f)
+		// f.WriteTo(os.Stderr)
+		lift(f)
+	}
+
+	f.namedResults = nil // (used by lifting)
+
+	numberRegisters(f)
+
+	if f.Prog.mode&PrintFunctions != 0 {
+		printMu.Lock()
+		f.WriteTo(os.Stdout)
+		printMu.Unlock()
+	}
+
+	if f.Prog.mode&SanityCheckFunctions != 0 {
+		mustSanityCheck(f, nil)
+	}
+}
+
+func (f *Function) RemoveNilBlocks() {
+	f.removeNilBlocks()
+}
+
+// removeNilBlocks eliminates nils from f.Blocks and updates each
+// BasicBlock.Index.  Use this after any pass that may delete blocks.
+//
+func (f *Function) removeNilBlocks() {
+	j := 0
+	for _, b := range f.Blocks {
+		if b != nil {
+			b.Index = j
+			f.Blocks[j] = b
+			j++
+		}
+	}
+	// Nil out f.Blocks[j:] to aid GC.
+	for i := j; i < len(f.Blocks); i++ {
+		f.Blocks[i] = nil
+	}
+	f.Blocks = f.Blocks[:j]
+}
+
+// SetDebugMode sets the debug mode for package pkg.  If true, all its
+// functions will include full debug info.  This greatly increases the
+// size of the instruction stream, and causes Functions to depend upon
+// the ASTs, potentially keeping them live in memory for longer.
+//
+func (pkg *Package) SetDebugMode(debug bool) {
+	// TODO(adonovan): do we want ast.File granularity?
+	pkg.debug = debug
+}
+
+// debugInfo reports whether debug info is wanted for this function.
+func (f *Function) debugInfo() bool {
+	return f.Pkg != nil && f.Pkg.debug
+}
+
+// addNamedLocal creates a local variable, adds it to function f and
+// returns it.  Its name and type are taken from obj.  Subsequent
+// calls to f.lookup(obj) will return the same local.
+//
+func (f *Function) addNamedLocal(obj types.Object) *Alloc {
+	l := f.addLocal(obj.Type(), obj.Pos())
+	l.Comment = obj.Name()
+	f.objects[obj] = l
+	return l
+}
+
+func (f *Function) addLocalForIdent(id *ast.Ident) *Alloc {
+	return f.addNamedLocal(f.Pkg.info.Defs[id])
+}
+
+// addLocal creates an anonymous local variable of type typ, adds it
+// to function f and returns it.  pos is the optional source location.
+//
+func (f *Function) addLocal(typ types.Type, pos token.Pos) *Alloc {
+	v := &Alloc{}
+	v.setType(types.NewPointer(typ))
+	v.setPos(pos)
+	f.Locals = append(f.Locals, v)
+	f.emit(v)
+	return v
+}
+
+// lookup returns the address of the named variable identified by obj
+// that is local to function f or one of its enclosing functions.
+// If escaping, the reference comes from a potentially escaping pointer
+// expression and the referent must be heap-allocated.
+//
+func (f *Function) lookup(obj types.Object, escaping bool) Value {
+	if v, ok := f.objects[obj]; ok {
+		if alloc, ok := v.(*Alloc); ok && escaping {
+			alloc.Heap = true
+		}
+		return v // function-local var (address)
+	}
+
+	// Definition must be in an enclosing function;
+	// plumb it through intervening closures.
+	if f.parent == nil {
+		panic("no ssa.Value for " + obj.String())
+	}
+	outer := f.parent.lookup(obj, true) // escaping
+	v := &FreeVar{
+		name:   obj.Name(),
+		typ:    outer.Type(),
+		pos:    outer.Pos(),
+		outer:  outer,
+		parent: f,
+	}
+	f.objects[obj] = v
+	f.FreeVars = append(f.FreeVars, v)
+	return v
+}
+
+// emit emits the specified instruction to function f.
+func (f *Function) emit(instr Instruction) Value {
+	return f.currentBlock.emit(instr)
+}
+
+// RelString returns the full name of this function, qualified by
+// package name, receiver type, etc.
+//
+// The specific formatting rules are not guaranteed and may change.
+//
+// Examples:
+//      "math.IsNaN"                  // a package-level function
+//      "(*bytes.Buffer).Bytes"       // a declared method or a wrapper
+//      "(*bytes.Buffer).Bytes$thunk" // thunk (func wrapping method; receiver is param 0)
+//      "(*bytes.Buffer).Bytes$bound" // bound (func wrapping method; receiver supplied by closure)
+//      "main.main$1"                 // an anonymous function in main
+//      "main.init#1"                 // a declared init function
+//      "main.init"                   // the synthesized package initializer
+//
+// When these functions are referred to from within the same package
+// (i.e. from == f.Pkg.Object), they are rendered without the package path.
+// For example: "IsNaN", "(*Buffer).Bytes", etc.
+//
+// All non-synthetic functions have distinct package-qualified names.
+// (But two methods may have the same name "(T).f" if one is a synthetic
+// wrapper promoting a non-exported method "f" from another package; in
+// that case, the strings are equal but the identifiers "f" are distinct.)
+//
+func (f *Function) RelString(from *types.Package) string {
+	// Anonymous?
+	if f.parent != nil {
+		// An anonymous function's Name() looks like "parentName$1",
+		// but its String() should include the type/package/etc.
+		parent := f.parent.RelString(from)
+		for i, anon := range f.parent.AnonFuncs {
+			if anon == f {
+				return fmt.Sprintf("%s$%d", parent, 1+i)
+			}
+		}
+
+		return f.name // should never happen
+	}
+
+	// Method (declared or wrapper)?
+	if recv := f.Signature.Recv(); recv != nil {
+		return f.relMethod(from, recv.Type())
+	}
+
+	// Thunk?
+	if f.method != nil {
+		return f.relMethod(from, f.method.Recv())
+	}
+
+	// Bound?
+	if len(f.FreeVars) == 1 && strings.HasSuffix(f.name, "$bound") {
+		return f.relMethod(from, f.FreeVars[0].Type())
+	}
+
+	// Package-level function?
+	// Prefix with package name for cross-package references only.
+	if p := f.pkg(); p != nil && p != from {
+		return fmt.Sprintf("%s.%s", p.Path(), f.name)
+	}
+
+	// Unknown.
+	return f.name
+}
+
+func (f *Function) relMethod(from *types.Package, recv types.Type) string {
+	return fmt.Sprintf("(%s).%s", relType(recv, from), f.name)
+}
+
+// writeSignature writes to buf the signature sig in declaration syntax.
+func writeSignature(buf *bytes.Buffer, from *types.Package, name string, sig *types.Signature, params []*Parameter) {
+	buf.WriteString("func ")
+	if recv := sig.Recv(); recv != nil {
+		buf.WriteString("(")
+		if n := params[0].Name(); n != "" {
+			buf.WriteString(n)
+			buf.WriteString(" ")
+		}
+		types.WriteType(buf, params[0].Type(), types.RelativeTo(from))
+		buf.WriteString(") ")
+	}
+	buf.WriteString(name)
+	types.WriteSignature(buf, sig, types.RelativeTo(from))
+}
+
+func (f *Function) pkg() *types.Package {
+	if f.Pkg != nil {
+		return f.Pkg.Pkg
+	}
+	return nil
+}
+
+var _ io.WriterTo = (*Function)(nil) // *Function implements io.Writer
+
+func (f *Function) WriteTo(w io.Writer) (int64, error) {
+	var buf bytes.Buffer
+	WriteFunction(&buf, f)
+	n, err := w.Write(buf.Bytes())
+	return int64(n), err
+}
+
+// WriteFunction writes to buf a human-readable "disassembly" of f.
+func WriteFunction(buf *bytes.Buffer, f *Function) {
+	fmt.Fprintf(buf, "# Name: %s\n", f.String())
+	if f.Pkg != nil {
+		fmt.Fprintf(buf, "# Package: %s\n", f.Pkg.Pkg.Path())
+	}
+	if syn := f.Synthetic; syn != "" {
+		fmt.Fprintln(buf, "# Synthetic:", syn)
+	}
+	if pos := f.Pos(); pos.IsValid() {
+		fmt.Fprintf(buf, "# Location: %s\n", f.Prog.Fset.Position(pos))
+	}
+
+	if f.parent != nil {
+		fmt.Fprintf(buf, "# Parent: %s\n", f.parent.Name())
+	}
+
+	if f.Recover != nil {
+		fmt.Fprintf(buf, "# Recover: %s\n", f.Recover)
+	}
+
+	from := f.pkg()
+
+	if f.FreeVars != nil {
+		buf.WriteString("# Free variables:\n")
+		for i, fv := range f.FreeVars {
+			fmt.Fprintf(buf, "# % 3d:\t%s %s\n", i, fv.Name(), relType(fv.Type(), from))
+		}
+	}
+
+	if len(f.Locals) > 0 {
+		buf.WriteString("# Locals:\n")
+		for i, l := range f.Locals {
+			fmt.Fprintf(buf, "# % 3d:\t%s %s\n", i, l.Name(), relType(deref(l.Type()), from))
+		}
+	}
+	writeSignature(buf, from, f.Name(), f.Signature, f.Params)
+	buf.WriteString(":\n")
+
+	if f.Blocks == nil {
+		buf.WriteString("\t(external)\n")
+	}
+
+	// NB. column calculations are confused by non-ASCII
+	// characters and assume 8-space tabs.
+	const punchcard = 80 // for old time's sake.
+	const tabwidth = 8
+	for _, b := range f.Blocks {
+		if b == nil {
+			// Corrupt CFG.
+			fmt.Fprintf(buf, ".nil:\n")
+			continue
+		}
+		n, _ := fmt.Fprintf(buf, "%d:", b.Index)
+		bmsg := fmt.Sprintf("%s P:%d S:%d", b.Comment, len(b.Preds), len(b.Succs))
+		fmt.Fprintf(buf, "%*s%s\n", punchcard-1-n-len(bmsg), "", bmsg)
+
+		if false { // CFG debugging
+			fmt.Fprintf(buf, "\t# CFG: %s --> %s --> %s\n", b.Preds, b, b.Succs)
+		}
+		for _, instr := range b.Instrs {
+			buf.WriteString("\t")
+			switch v := instr.(type) {
+			case Value:
+				l := punchcard - tabwidth
+				// Left-align the instruction.
+				if name := v.Name(); name != "" {
+					n, _ := fmt.Fprintf(buf, "%s = ", name)
+					l -= n
+				}
+				n, _ := buf.WriteString(instr.String())
+				l -= n
+				// Right-align the type if there's space.
+				if t := v.Type(); t != nil {
+					buf.WriteByte(' ')
+					ts := relType(t, from)
+					l -= len(ts) + len("  ") // (spaces before and after type)
+					if l > 0 {
+						fmt.Fprintf(buf, "%*s", l, "")
+					}
+					buf.WriteString(ts)
+				}
+			case nil:
+				// Be robust against bad transforms.
+				buf.WriteString("<deleted>")
+			default:
+				buf.WriteString(instr.String())
+			}
+			buf.WriteString("\n")
+		}
+	}
+	fmt.Fprintf(buf, "\n")
+}
+
+// newBasicBlock adds to f a new basic block and returns it.  It does
+// not automatically become the current block for subsequent calls to emit.
+// comment is an optional string for more readable debugging output.
+//
+func (f *Function) newBasicBlock(comment string) *BasicBlock {
+	b := &BasicBlock{
+		Index:   len(f.Blocks),
+		Comment: comment,
+		parent:  f,
+	}
+	b.Succs = b.succs2[:0]
+	f.Blocks = append(f.Blocks, b)
+	return b
+}
+
+// NewFunction returns a new synthetic Function instance belonging to
+// prog, with its name and signature fields set as specified.
+//
+// The caller is responsible for initializing the remaining fields of
+// the function object, e.g. Pkg, Params, Blocks.
+//
+// It is practically impossible for clients to construct well-formed
+// SSA functions/packages/programs directly, so we assume this is the
+// job of the Builder alone.  NewFunction exists to provide clients a
+// little flexibility.  For example, analysis tools may wish to
+// construct fake Functions for the root of the callgraph, a fake
+// "reflect" package, etc.
+//
+// TODO(adonovan): think harder about the API here.
+//
+func (prog *Program) NewFunction(name string, sig *types.Signature, provenance string) *Function {
+	return &Function{Prog: prog, name: name, Signature: sig, Synthetic: provenance}
+}
+
+type extentNode [2]token.Pos
+
+func (n extentNode) Pos() token.Pos { return n[0] }
+func (n extentNode) End() token.Pos { return n[1] }
+
+// Syntax returns an ast.Node whose Pos/End methods provide the
+// lexical extent of the function if it was defined by Go source code
+// (f.Synthetic==""), or nil otherwise.
+//
+// If f was built with debug information (see Package.SetDebugRef),
+// the result is the *ast.FuncDecl or *ast.FuncLit that declared the
+// function.  Otherwise, it is an opaque Node providing only position
+// information; this avoids pinning the AST in memory.
+//
+func (f *Function) Syntax() ast.Node { return f.syntax }

vendor/honnef.co/go/tools/ssa/identical.go

@@ -0,0 +1,7 @@
+// +build go1.8
+
+package ssa
+
+import "go/types"
+
+var structTypesIdentical = types.IdenticalIgnoreTags

vendor/honnef.co/go/tools/ssa/identical_17.go

@@ -0,0 +1,7 @@
+// +build !go1.8
+
+package ssa
+
+import "go/types"
+
+var structTypesIdentical = types.Identical

vendor/honnef.co/go/tools/ssa/lift.go

@@ -0,0 +1,653 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+// This file defines the lifting pass which tries to "lift" Alloc
+// cells (new/local variables) into SSA registers, replacing loads
+// with the dominating stored value, eliminating loads and stores, and
+// inserting φ-nodes as needed.
+
+// Cited papers and resources:
+//
+// Ron Cytron et al. 1991. Efficiently computing SSA form...
+// http://doi.acm.org/10.1145/115372.115320
+//
+// Cooper, Harvey, Kennedy.  2001.  A Simple, Fast Dominance Algorithm.
+// Software Practice and Experience 2001, 4:1-10.
+// http://www.hipersoft.rice.edu/grads/publications/dom14.pdf
+//
+// Daniel Berlin, llvmdev mailing list, 2012.
+// http://lists.cs.uiuc.edu/pipermail/llvmdev/2012-January/046638.html
+// (Be sure to expand the whole thread.)
+
+// TODO(adonovan): opt: there are many optimizations worth evaluating, and
+// the conventional wisdom for SSA construction is that a simple
+// algorithm well engineered often beats those of better asymptotic
+// complexity on all but the most egregious inputs.
+//
+// Danny Berlin suggests that the Cooper et al. algorithm for
+// computing the dominance frontier is superior to Cytron et al.
+// Furthermore he recommends that rather than computing the DF for the
+// whole function then renaming all alloc cells, it may be cheaper to
+// compute the DF for each alloc cell separately and throw it away.
+//
+// Consider exploiting liveness information to avoid creating dead
+// φ-nodes which we then immediately remove.
+//
+// Also see many other "TODO: opt" suggestions in the code.
+
+import (
+	"fmt"
+	"go/token"
+	"go/types"
+	"math/big"
+	"os"
+)
+
+// If true, show diagnostic information at each step of lifting.
+// Very verbose.
+const debugLifting = false
+
+// domFrontier maps each block to the set of blocks in its dominance
+// frontier.  The outer slice is conceptually a map keyed by
+// Block.Index.  The inner slice is conceptually a set, possibly
+// containing duplicates.
+//
+// TODO(adonovan): opt: measure impact of dups; consider a packed bit
+// representation, e.g. big.Int, and bitwise parallel operations for
+// the union step in the Children loop.
+//
+// domFrontier's methods mutate the slice's elements but not its
+// length, so their receivers needn't be pointers.
+//
+type domFrontier [][]*BasicBlock
+
+func (df domFrontier) add(u, v *BasicBlock) {
+	p := &df[u.Index]
+	*p = append(*p, v)
+}
+
+// build builds the dominance frontier df for the dominator (sub)tree
+// rooted at u, using the Cytron et al. algorithm.
+//
+// TODO(adonovan): opt: consider Berlin approach, computing pruned SSA
+// by pruning the entire IDF computation, rather than merely pruning
+// the DF -> IDF step.
+func (df domFrontier) build(u *BasicBlock) {
+	// Encounter each node u in postorder of dom tree.
+	for _, child := range u.dom.children {
+		df.build(child)
+	}
+	for _, vb := range u.Succs {
+		if v := vb.dom; v.idom != u {
+			df.add(u, vb)
+		}
+	}
+	for _, w := range u.dom.children {
+		for _, vb := range df[w.Index] {
+			// TODO(adonovan): opt: use word-parallel bitwise union.
+			if v := vb.dom; v.idom != u {
+				df.add(u, vb)
+			}
+		}
+	}
+}
+
+func buildDomFrontier(fn *Function) domFrontier {
+	df := make(domFrontier, len(fn.Blocks))
+	df.build(fn.Blocks[0])
+	if fn.Recover != nil {
+		df.build(fn.Recover)
+	}
+	return df
+}
+
+func removeInstr(refs []Instruction, instr Instruction) []Instruction {
+	i := 0
+	for _, ref := range refs {
+		if ref == instr {
+			continue
+		}
+		refs[i] = ref
+		i++
+	}
+	for j := i; j != len(refs); j++ {
+		refs[j] = nil // aid GC
+	}
+	return refs[:i]
+}
+
+// lift replaces local and new Allocs accessed only with
+// load/store by SSA registers, inserting φ-nodes where necessary.
+// The result is a program in classical pruned SSA form.
+//
+// Preconditions:
+// - fn has no dead blocks (blockopt has run).
+// - Def/use info (Operands and Referrers) is up-to-date.
+// - The dominator tree is up-to-date.
+//
+func lift(fn *Function) {
+	// TODO(adonovan): opt: lots of little optimizations may be
+	// worthwhile here, especially if they cause us to avoid
+	// buildDomFrontier.  For example:
+	//
+	// - Alloc never loaded?  Eliminate.
+	// - Alloc never stored?  Replace all loads with a zero constant.
+	// - Alloc stored once?  Replace loads with dominating store;
+	//   don't forget that an Alloc is itself an effective store
+	//   of zero.
+	// - Alloc used only within a single block?
+	//   Use degenerate algorithm avoiding φ-nodes.
+	// - Consider synergy with scalar replacement of aggregates (SRA).
+	//   e.g. *(&x.f) where x is an Alloc.
+	//   Perhaps we'd get better results if we generated this as x.f
+	//   i.e. Field(x, .f) instead of Load(FieldIndex(x, .f)).
+	//   Unclear.
+	//
+	// But we will start with the simplest correct code.
+	df := buildDomFrontier(fn)
+
+	if debugLifting {
+		title := false
+		for i, blocks := range df {
+			if blocks != nil {
+				if !title {
+					fmt.Fprintf(os.Stderr, "Dominance frontier of %s:\n", fn)
+					title = true
+				}
+				fmt.Fprintf(os.Stderr, "\t%s: %s\n", fn.Blocks[i], blocks)
+			}
+		}
+	}
+
+	newPhis := make(newPhiMap)
+
+	// During this pass we will replace some BasicBlock.Instrs
+	// (allocs, loads and stores) with nil, keeping a count in
+	// BasicBlock.gaps.  At the end we will reset Instrs to the
+	// concatenation of all non-dead newPhis and non-nil Instrs
+	// for the block, reusing the original array if space permits.
+
+	// While we're here, we also eliminate 'rundefers'
+	// instructions in functions that contain no 'defer'
+	// instructions.
+	usesDefer := false
+
+	// A counter used to generate ~unique ids for Phi nodes, as an
+	// aid to debugging.  We use large numbers to make them highly
+	// visible.  All nodes are renumbered later.
+	fresh := 1000
+
+	// Determine which allocs we can lift and number them densely.
+	// The renaming phase uses this numbering for compact maps.
+	numAllocs := 0
+	for _, b := range fn.Blocks {
+		b.gaps = 0
+		b.rundefers = 0
+		for _, instr := range b.Instrs {
+			switch instr := instr.(type) {
+			case *Alloc:
+				index := -1
+				if liftAlloc(df, instr, newPhis, &fresh) {
+					index = numAllocs
+					numAllocs++
+				}
+				instr.index = index
+			case *Defer:
+				usesDefer = true
+			case *RunDefers:
+				b.rundefers++
+			}
+		}
+	}
+
+	// renaming maps an alloc (keyed by index) to its replacement
+	// value.  Initially the renaming contains nil, signifying the
+	// zero constant of the appropriate type; we construct the
+	// Const lazily at most once on each path through the domtree.
+	// TODO(adonovan): opt: cache per-function not per subtree.
+	renaming := make([]Value, numAllocs)
+
+	// Renaming.
+	rename(fn.Blocks[0], renaming, newPhis)
+
+	// Eliminate dead φ-nodes.
+	removeDeadPhis(fn.Blocks, newPhis)
+
+	// Prepend remaining live φ-nodes to each block.
+	for _, b := range fn.Blocks {
+		nps := newPhis[b]
+		j := len(nps)
+
+		rundefersToKill := b.rundefers
+		if usesDefer {
+			rundefersToKill = 0
+		}
+
+		if j+b.gaps+rundefersToKill == 0 {
+			continue // fast path: no new phis or gaps
+		}
+
+		// Compact nps + non-nil Instrs into a new slice.
+		// TODO(adonovan): opt: compact in situ (rightwards)
+		// if Instrs has sufficient space or slack.
+		dst := make([]Instruction, len(b.Instrs)+j-b.gaps-rundefersToKill)
+		for i, np := range nps {
+			dst[i] = np.phi
+		}
+		for _, instr := range b.Instrs {
+			if instr == nil {
+				continue
+			}
+			if !usesDefer {
+				if _, ok := instr.(*RunDefers); ok {
+					continue
+				}
+			}
+			dst[j] = instr
+			j++
+		}
+		b.Instrs = dst
+	}
+
+	// Remove any fn.Locals that were lifted.
+	j := 0
+	for _, l := range fn.Locals {
+		if l.index < 0 {
+			fn.Locals[j] = l
+			j++
+		}
+	}
+	// Nil out fn.Locals[j:] to aid GC.
+	for i := j; i < len(fn.Locals); i++ {
+		fn.Locals[i] = nil
+	}
+	fn.Locals = fn.Locals[:j]
+}
+
+// removeDeadPhis removes φ-nodes not transitively needed by a
+// non-Phi, non-DebugRef instruction.
+func removeDeadPhis(blocks []*BasicBlock, newPhis newPhiMap) {
+	// First pass: find the set of "live" φ-nodes: those reachable
+	// from some non-Phi instruction.
+	//
+	// We compute reachability in reverse, starting from each φ,
+	// rather than forwards, starting from each live non-Phi
+	// instruction, because this way visits much less of the
+	// Value graph.
+	livePhis := make(map[*Phi]bool)
+	for _, npList := range newPhis {
+		for _, np := range npList {
+			phi := np.phi
+			if !livePhis[phi] && phiHasDirectReferrer(phi) {
+				markLivePhi(livePhis, phi)
+			}
+		}
+	}
+
+	// Existing φ-nodes due to && and || operators
+	// are all considered live (see Go issue 19622).
+	for _, b := range blocks {
+		for _, phi := range b.phis() {
+			markLivePhi(livePhis, phi.(*Phi))
+		}
+	}
+
+	// Second pass: eliminate unused phis from newPhis.
+	for block, npList := range newPhis {
+		j := 0
+		for _, np := range npList {
+			if livePhis[np.phi] {
+				npList[j] = np
+				j++
+			} else {
+				// discard it, first removing it from referrers
+				for _, val := range np.phi.Edges {
+					if refs := val.Referrers(); refs != nil {
+						*refs = removeInstr(*refs, np.phi)
+					}
+				}
+				np.phi.block = nil
+			}
+		}
+		newPhis[block] = npList[:j]
+	}
+}
+
+// markLivePhi marks phi, and all φ-nodes transitively reachable via
+// its Operands, live.
+func markLivePhi(livePhis map[*Phi]bool, phi *Phi) {
+	livePhis[phi] = true
+	for _, rand := range phi.Operands(nil) {
+		if q, ok := (*rand).(*Phi); ok {
+			if !livePhis[q] {
+				markLivePhi(livePhis, q)
+			}
+		}
+	}
+}
+
+// phiHasDirectReferrer reports whether phi is directly referred to by
+// a non-Phi instruction.  Such instructions are the
+// roots of the liveness traversal.
+func phiHasDirectReferrer(phi *Phi) bool {
+	for _, instr := range *phi.Referrers() {
+		if _, ok := instr.(*Phi); !ok {
+			return true
+		}
+	}
+	return false
+}
+
+type blockSet struct{ big.Int } // (inherit methods from Int)
+
+// add adds b to the set and returns true if the set changed.
+func (s *blockSet) add(b *BasicBlock) bool {
+	i := b.Index
+	if s.Bit(i) != 0 {
+		return false
+	}
+	s.SetBit(&s.Int, i, 1)
+	return true
+}
+
+// take removes an arbitrary element from a set s and
+// returns its index, or returns -1 if empty.
+func (s *blockSet) take() int {
+	l := s.BitLen()
+	for i := 0; i < l; i++ {
+		if s.Bit(i) == 1 {
+			s.SetBit(&s.Int, i, 0)
+			return i
+		}
+	}
+	return -1
+}
+
+// newPhi is a pair of a newly introduced φ-node and the lifted Alloc
+// it replaces.
+type newPhi struct {
+	phi   *Phi
+	alloc *Alloc
+}
+
+// newPhiMap records for each basic block, the set of newPhis that
+// must be prepended to the block.
+type newPhiMap map[*BasicBlock][]newPhi
+
+// liftAlloc determines whether alloc can be lifted into registers,
+// and if so, it populates newPhis with all the φ-nodes it may require
+// and returns true.
+//
+// fresh is a source of fresh ids for phi nodes.
+//
+func liftAlloc(df domFrontier, alloc *Alloc, newPhis newPhiMap, fresh *int) bool {
+	// Don't lift aggregates into registers, because we don't have
+	// a way to express their zero-constants.
+	switch deref(alloc.Type()).Underlying().(type) {
+	case *types.Array, *types.Struct:
+		return false
+	}
+
+	// Don't lift named return values in functions that defer
+	// calls that may recover from panic.
+	if fn := alloc.Parent(); fn.Recover != nil {
+		for _, nr := range fn.namedResults {
+			if nr == alloc {
+				return false
+			}
+		}
+	}
+
+	// Compute defblocks, the set of blocks containing a
+	// definition of the alloc cell.
+	var defblocks blockSet
+	for _, instr := range *alloc.Referrers() {
+		// Bail out if we discover the alloc is not liftable;
+		// the only operations permitted to use the alloc are
+		// loads/stores into the cell, and DebugRef.
+		switch instr := instr.(type) {
+		case *Store:
+			if instr.Val == alloc {
+				return false // address used as value
+			}
+			if instr.Addr != alloc {
+				panic("Alloc.Referrers is inconsistent")
+			}
+			defblocks.add(instr.Block())
+		case *UnOp:
+			if instr.Op != token.MUL {
+				return false // not a load
+			}
+			if instr.X != alloc {
+				panic("Alloc.Referrers is inconsistent")
+			}
+		case *DebugRef:
+			// ok
+		default:
+			return false // some other instruction
+		}
+	}
+	// The Alloc itself counts as a (zero) definition of the cell.
+	defblocks.add(alloc.Block())
+
+	if debugLifting {
+		fmt.Fprintln(os.Stderr, "\tlifting ", alloc, alloc.Name())
+	}
+
+	fn := alloc.Parent()
+
+	// Φ-insertion.
+	//
+	// What follows is the body of the main loop of the insert-φ
+	// function described by Cytron et al, but instead of using
+	// counter tricks, we just reset the 'hasAlready' and 'work'
+	// sets each iteration.  These are bitmaps so it's pretty cheap.
+	//
+	// TODO(adonovan): opt: recycle slice storage for W,
+	// hasAlready, defBlocks across liftAlloc calls.
+	var hasAlready blockSet
+
+	// Initialize W and work to defblocks.
+	var work blockSet = defblocks // blocks seen
+	var W blockSet                // blocks to do
+	W.Set(&defblocks.Int)
+
+	// Traverse iterated dominance frontier, inserting φ-nodes.
+	for i := W.take(); i != -1; i = W.take() {
+		u := fn.Blocks[i]
+		for _, v := range df[u.Index] {
+			if hasAlready.add(v) {
+				// Create φ-node.
+				// It will be prepended to v.Instrs later, if needed.
+				phi := &Phi{
+					Edges:   make([]Value, len(v.Preds)),
+					Comment: alloc.Comment,
+				}
+				// This is merely a debugging aid:
+				phi.setNum(*fresh)
+				*fresh++
+
+				phi.pos = alloc.Pos()
+				phi.setType(deref(alloc.Type()))
+				phi.block = v
+				if debugLifting {
+					fmt.Fprintf(os.Stderr, "\tplace %s = %s at block %s\n", phi.Name(), phi, v)
+				}
+				newPhis[v] = append(newPhis[v], newPhi{phi, alloc})
+
+				if work.add(v) {
+					W.add(v)
+				}
+			}
+		}
+	}
+
+	return true
+}
+
+// replaceAll replaces all intraprocedural uses of x with y,
+// updating x.Referrers and y.Referrers.
+// Precondition: x.Referrers() != nil, i.e. x must be local to some function.
+//
+func replaceAll(x, y Value) {
+	var rands []*Value
+	pxrefs := x.Referrers()
+	pyrefs := y.Referrers()
+	for _, instr := range *pxrefs {
+		rands = instr.Operands(rands[:0]) // recycle storage
+		for _, rand := range rands {
+			if *rand != nil {
+				if *rand == x {
+					*rand = y
+				}
+			}
+		}
+		if pyrefs != nil {
+			*pyrefs = append(*pyrefs, instr) // dups ok
+		}
+	}
+	*pxrefs = nil // x is now unreferenced
+}
+
+// renamed returns the value to which alloc is being renamed,
+// constructing it lazily if it's the implicit zero initialization.
+//
+func renamed(renaming []Value, alloc *Alloc) Value {
+	v := renaming[alloc.index]
+	if v == nil {
+		v = zeroConst(deref(alloc.Type()))
+		renaming[alloc.index] = v
+	}
+	return v
+}
+
+// rename implements the (Cytron et al) SSA renaming algorithm, a
+// preorder traversal of the dominator tree replacing all loads of
+// Alloc cells with the value stored to that cell by the dominating
+// store instruction.  For lifting, we need only consider loads,
+// stores and φ-nodes.
+//
+// renaming is a map from *Alloc (keyed by index number) to its
+// dominating stored value; newPhis[x] is the set of new φ-nodes to be
+// prepended to block x.
+//
+func rename(u *BasicBlock, renaming []Value, newPhis newPhiMap) {
+	// Each φ-node becomes the new name for its associated Alloc.
+	for _, np := range newPhis[u] {
+		phi := np.phi
+		alloc := np.alloc
+		renaming[alloc.index] = phi
+	}
+
+	// Rename loads and stores of allocs.
+	for i, instr := range u.Instrs {
+		switch instr := instr.(type) {
+		case *Alloc:
+			if instr.index >= 0 { // store of zero to Alloc cell
+				// Replace dominated loads by the zero value.
+				renaming[instr.index] = nil
+				if debugLifting {
+					fmt.Fprintf(os.Stderr, "\tkill alloc %s\n", instr)
+				}
+				// Delete the Alloc.
+				u.Instrs[i] = nil
+				u.gaps++
+			}
+
+		case *Store:
+			if alloc, ok := instr.Addr.(*Alloc); ok && alloc.index >= 0 { // store to Alloc cell
+				// Replace dominated loads by the stored value.
+				renaming[alloc.index] = instr.Val
+				if debugLifting {
+					fmt.Fprintf(os.Stderr, "\tkill store %s; new value: %s\n",
+						instr, instr.Val.Name())
+				}
+				// Remove the store from the referrer list of the stored value.
+				if refs := instr.Val.Referrers(); refs != nil {
+					*refs = removeInstr(*refs, instr)
+				}
+				// Delete the Store.
+				u.Instrs[i] = nil
+				u.gaps++
+			}
+
+		case *UnOp:
+			if instr.Op == token.MUL {
+				if alloc, ok := instr.X.(*Alloc); ok && alloc.index >= 0 { // load of Alloc cell
+					newval := renamed(renaming, alloc)
+					if debugLifting {
+						fmt.Fprintf(os.Stderr, "\tupdate load %s = %s with %s\n",
+							instr.Name(), instr, newval.Name())
+					}
+					// Replace all references to
+					// the loaded value by the
+					// dominating stored value.
+					replaceAll(instr, newval)
+					// Delete the Load.
+					u.Instrs[i] = nil
+					u.gaps++
+				}
+			}
+
+		case *DebugRef:
+			if alloc, ok := instr.X.(*Alloc); ok && alloc.index >= 0 { // ref of Alloc cell
+				if instr.IsAddr {
+					instr.X = renamed(renaming, alloc)
+					instr.IsAddr = false
+
+					// Add DebugRef to instr.X's referrers.
+					if refs := instr.X.Referrers(); refs != nil {
+						*refs = append(*refs, instr)
+					}
+				} else {
+					// A source expression denotes the address
+					// of an Alloc that was optimized away.
+					instr.X = nil
+
+					// Delete the DebugRef.
+					u.Instrs[i] = nil
+					u.gaps++
+				}
+			}
+		}
+	}
+
+	// For each φ-node in a CFG successor, rename the edge.
+	for _, v := range u.Succs {
+		phis := newPhis[v]
+		if len(phis) == 0 {
+			continue
+		}
+		i := v.predIndex(u)
+		for _, np := range phis {
+			phi := np.phi
+			alloc := np.alloc
+			newval := renamed(renaming, alloc)
+			if debugLifting {
+				fmt.Fprintf(os.Stderr, "\tsetphi %s edge %s -> %s (#%d) (alloc=%s) := %s\n",
+					phi.Name(), u, v, i, alloc.Name(), newval.Name())
+			}
+			phi.Edges[i] = newval
+			if prefs := newval.Referrers(); prefs != nil {
+				*prefs = append(*prefs, phi)
+			}
+		}
+	}
+
+	// Continue depth-first recursion over domtree, pushing a
+	// fresh copy of the renaming map for each subtree.
+	for i, v := range u.dom.children {
+		r := renaming
+		if i < len(u.dom.children)-1 {
+			// On all but the final iteration, we must make
+			// a copy to avoid destructive update.
+			r = make([]Value, len(renaming))
+			copy(r, renaming)
+		}
+		rename(v, r, newPhis)
+	}
+
+}

vendor/honnef.co/go/tools/ssa/lvalue.go

@@ -0,0 +1,123 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+// lvalues are the union of addressable expressions and map-index
+// expressions.
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+)
+
+// An lvalue represents an assignable location that may appear on the
+// left-hand side of an assignment.  This is a generalization of a
+// pointer to permit updates to elements of maps.
+//
+type lvalue interface {
+	store(fn *Function, v Value) // stores v into the location
+	load(fn *Function) Value     // loads the contents of the location
+	address(fn *Function) Value  // address of the location
+	typ() types.Type             // returns the type of the location
+}
+
+// An address is an lvalue represented by a true pointer.
+type address struct {
+	addr Value
+	pos  token.Pos // source position
+	expr ast.Expr  // source syntax of the value (not address) [debug mode]
+}
+
+func (a *address) load(fn *Function) Value {
+	load := emitLoad(fn, a.addr)
+	load.pos = a.pos
+	return load
+}
+
+func (a *address) store(fn *Function, v Value) {
+	store := emitStore(fn, a.addr, v, a.pos)
+	if a.expr != nil {
+		// store.Val is v, converted for assignability.
+		emitDebugRef(fn, a.expr, store.Val, false)
+	}
+}
+
+func (a *address) address(fn *Function) Value {
+	if a.expr != nil {
+		emitDebugRef(fn, a.expr, a.addr, true)
+	}
+	return a.addr
+}
+
+func (a *address) typ() types.Type {
+	return deref(a.addr.Type())
+}
+
+// An element is an lvalue represented by m[k], the location of an
+// element of a map or string.  These locations are not addressable
+// since pointers cannot be formed from them, but they do support
+// load(), and in the case of maps, store().
+//
+type element struct {
+	m, k Value      // map or string
+	t    types.Type // map element type or string byte type
+	pos  token.Pos  // source position of colon ({k:v}) or lbrack (m[k]=v)
+}
+
+func (e *element) load(fn *Function) Value {
+	l := &Lookup{
+		X:     e.m,
+		Index: e.k,
+	}
+	l.setPos(e.pos)
+	l.setType(e.t)
+	return fn.emit(l)
+}
+
+func (e *element) store(fn *Function, v Value) {
+	up := &MapUpdate{
+		Map:   e.m,
+		Key:   e.k,
+		Value: emitConv(fn, v, e.t),
+	}
+	up.pos = e.pos
+	fn.emit(up)
+}
+
+func (e *element) address(fn *Function) Value {
+	panic("map/string elements are not addressable")
+}
+
+func (e *element) typ() types.Type {
+	return e.t
+}
+
+// A blank is a dummy variable whose name is "_".
+// It is not reified: loads are illegal and stores are ignored.
+//
+type blank struct{}
+
+func (bl blank) load(fn *Function) Value {
+	panic("blank.load is illegal")
+}
+
+func (bl blank) store(fn *Function, v Value) {
+	s := &BlankStore{
+		Val: v,
+	}
+	fn.emit(s)
+}
+
+func (bl blank) address(fn *Function) Value {
+	panic("blank var is not addressable")
+}
+
+func (bl blank) typ() types.Type {
+	// This should be the type of the blank Ident; the typechecker
+	// doesn't provide this yet, but fortunately, we don't need it
+	// yet either.
+	panic("blank.typ is unimplemented")
+}

vendor/honnef.co/go/tools/ssa/methods.go

@@ -0,0 +1,239 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+// This file defines utilities for population of method sets.
+
+import (
+	"fmt"
+	"go/types"
+)
+
+// MethodValue returns the Function implementing method sel, building
+// wrapper methods on demand.  It returns nil if sel denotes an
+// abstract (interface) method.
+//
+// Precondition: sel.Kind() == MethodVal.
+//
+// Thread-safe.
+//
+// EXCLUSIVE_LOCKS_ACQUIRED(prog.methodsMu)
+//
+func (prog *Program) MethodValue(sel *types.Selection) *Function {
+	if sel.Kind() != types.MethodVal {
+		panic(fmt.Sprintf("Method(%s) kind != MethodVal", sel))
+	}
+	T := sel.Recv()
+	if isInterface(T) {
+		return nil // abstract method
+	}
+	if prog.mode&LogSource != 0 {
+		defer logStack("Method %s %v", T, sel)()
+	}
+
+	prog.methodsMu.Lock()
+	defer prog.methodsMu.Unlock()
+
+	return prog.addMethod(prog.createMethodSet(T), sel)
+}
+
+// LookupMethod returns the implementation of the method of type T
+// identified by (pkg, name).  It returns nil if the method exists but
+// is abstract, and panics if T has no such method.
+//
+func (prog *Program) LookupMethod(T types.Type, pkg *types.Package, name string) *Function {
+	sel := prog.MethodSets.MethodSet(T).Lookup(pkg, name)
+	if sel == nil {
+		panic(fmt.Sprintf("%s has no method %s", T, types.Id(pkg, name)))
+	}
+	return prog.MethodValue(sel)
+}
+
+// methodSet contains the (concrete) methods of a non-interface type.
+type methodSet struct {
+	mapping  map[string]*Function // populated lazily
+	complete bool                 // mapping contains all methods
+}
+
+// Precondition: !isInterface(T).
+// EXCLUSIVE_LOCKS_REQUIRED(prog.methodsMu)
+func (prog *Program) createMethodSet(T types.Type) *methodSet {
+	mset, ok := prog.methodSets.At(T).(*methodSet)
+	if !ok {
+		mset = &methodSet{mapping: make(map[string]*Function)}
+		prog.methodSets.Set(T, mset)
+	}
+	return mset
+}
+
+// EXCLUSIVE_LOCKS_REQUIRED(prog.methodsMu)
+func (prog *Program) addMethod(mset *methodSet, sel *types.Selection) *Function {
+	if sel.Kind() == types.MethodExpr {
+		panic(sel)
+	}
+	id := sel.Obj().Id()
+	fn := mset.mapping[id]
+	if fn == nil {
+		obj := sel.Obj().(*types.Func)
+
+		needsPromotion := len(sel.Index()) > 1
+		needsIndirection := !isPointer(recvType(obj)) && isPointer(sel.Recv())
+		if needsPromotion || needsIndirection {
+			fn = makeWrapper(prog, sel)
+		} else {
+			fn = prog.declaredFunc(obj)
+		}
+		if fn.Signature.Recv() == nil {
+			panic(fn) // missing receiver
+		}
+		mset.mapping[id] = fn
+	}
+	return fn
+}
+
+// RuntimeTypes returns a new unordered slice containing all
+// concrete types in the program for which a complete (non-empty)
+// method set is required at run-time.
+//
+// Thread-safe.
+//
+// EXCLUSIVE_LOCKS_ACQUIRED(prog.methodsMu)
+//
+func (prog *Program) RuntimeTypes() []types.Type {
+	prog.methodsMu.Lock()
+	defer prog.methodsMu.Unlock()
+
+	var res []types.Type
+	prog.methodSets.Iterate(func(T types.Type, v interface{}) {
+		if v.(*methodSet).complete {
+			res = append(res, T)
+		}
+	})
+	return res
+}
+
+// declaredFunc returns the concrete function/method denoted by obj.
+// Panic ensues if there is none.
+//
+func (prog *Program) declaredFunc(obj *types.Func) *Function {
+	if v := prog.packageLevelValue(obj); v != nil {
+		return v.(*Function)
+	}
+	panic("no concrete method: " + obj.String())
+}
+
+// needMethodsOf ensures that runtime type information (including the
+// complete method set) is available for the specified type T and all
+// its subcomponents.
+//
+// needMethodsOf must be called for at least every type that is an
+// operand of some MakeInterface instruction, and for the type of
+// every exported package member.
+//
+// Precondition: T is not a method signature (*Signature with Recv()!=nil).
+//
+// Thread-safe.  (Called via emitConv from multiple builder goroutines.)
+//
+// TODO(adonovan): make this faster.  It accounts for 20% of SSA build time.
+//
+// EXCLUSIVE_LOCKS_ACQUIRED(prog.methodsMu)
+//
+func (prog *Program) needMethodsOf(T types.Type) {
+	prog.methodsMu.Lock()
+	prog.needMethods(T, false)
+	prog.methodsMu.Unlock()
+}
+
+// Precondition: T is not a method signature (*Signature with Recv()!=nil).
+// Recursive case: skip => don't create methods for T.
+//
+// EXCLUSIVE_LOCKS_REQUIRED(prog.methodsMu)
+//
+func (prog *Program) needMethods(T types.Type, skip bool) {
+	// Each package maintains its own set of types it has visited.
+	if prevSkip, ok := prog.runtimeTypes.At(T).(bool); ok {
+		// needMethods(T) was previously called
+		if !prevSkip || skip {
+			return // already seen, with same or false 'skip' value
+		}
+	}
+	prog.runtimeTypes.Set(T, skip)
+
+	tmset := prog.MethodSets.MethodSet(T)
+
+	if !skip && !isInterface(T) && tmset.Len() > 0 {
+		// Create methods of T.
+		mset := prog.createMethodSet(T)
+		if !mset.complete {
+			mset.complete = true
+			n := tmset.Len()
+			for i := 0; i < n; i++ {
+				prog.addMethod(mset, tmset.At(i))
+			}
+		}
+	}
+
+	// Recursion over signatures of each method.
+	for i := 0; i < tmset.Len(); i++ {
+		sig := tmset.At(i).Type().(*types.Signature)
+		prog.needMethods(sig.Params(), false)
+		prog.needMethods(sig.Results(), false)
+	}
+
+	switch t := T.(type) {
+	case *types.Basic:
+		// nop
+
+	case *types.Interface:
+		// nop---handled by recursion over method set.
+
+	case *types.Pointer:
+		prog.needMethods(t.Elem(), false)
+
+	case *types.Slice:
+		prog.needMethods(t.Elem(), false)
+
+	case *types.Chan:
+		prog.needMethods(t.Elem(), false)
+
+	case *types.Map:
+		prog.needMethods(t.Key(), false)
+		prog.needMethods(t.Elem(), false)
+
+	case *types.Signature:
+		if t.Recv() != nil {
+			panic(fmt.Sprintf("Signature %s has Recv %s", t, t.Recv()))
+		}
+		prog.needMethods(t.Params(), false)
+		prog.needMethods(t.Results(), false)
+
+	case *types.Named:
+		// A pointer-to-named type can be derived from a named
+		// type via reflection.  It may have methods too.
+		prog.needMethods(types.NewPointer(T), false)
+
+		// Consider 'type T struct{S}' where S has methods.
+		// Reflection provides no way to get from T to struct{S},
+		// only to S, so the method set of struct{S} is unwanted,
+		// so set 'skip' flag during recursion.
+		prog.needMethods(t.Underlying(), true)
+
+	case *types.Array:
+		prog.needMethods(t.Elem(), false)
+
+	case *types.Struct:
+		for i, n := 0, t.NumFields(); i < n; i++ {
+			prog.needMethods(t.Field(i).Type(), false)
+		}
+
+	case *types.Tuple:
+		for i, n := 0, t.Len(); i < n; i++ {
+			prog.needMethods(t.At(i).Type(), false)
+		}
+
+	default:
+		panic(T)
+	}
+}

vendor/honnef.co/go/tools/ssa/mode.go

@@ -0,0 +1,100 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+// This file defines the BuilderMode type and its command-line flag.
+
+import (
+	"bytes"
+	"fmt"
+)
+
+// BuilderMode is a bitmask of options for diagnostics and checking.
+//
+// *BuilderMode satisfies the flag.Value interface.  Example:
+//
+// 	var mode = ssa.BuilderMode(0)
+// 	func init() { flag.Var(&mode, "build", ssa.BuilderModeDoc) }
+//
+type BuilderMode uint
+
+const (
+	PrintPackages        BuilderMode = 1 << iota // Print package inventory to stdout
+	PrintFunctions                               // Print function SSA code to stdout
+	LogSource                                    // Log source locations as SSA builder progresses
+	SanityCheckFunctions                         // Perform sanity checking of function bodies
+	NaiveForm                                    // Build naïve SSA form: don't replace local loads/stores with registers
+	BuildSerially                                // Build packages serially, not in parallel.
+	GlobalDebug                                  // Enable debug info for all packages
+	BareInits                                    // Build init functions without guards or calls to dependent inits
+)
+
+const BuilderModeDoc = `Options controlling the SSA builder.
+The value is a sequence of zero or more of these letters:
+C	perform sanity [C]hecking of the SSA form.
+D	include [D]ebug info for every function.
+P	print [P]ackage inventory.
+F	print [F]unction SSA code.
+S	log [S]ource locations as SSA builder progresses.
+L	build distinct packages seria[L]ly instead of in parallel.
+N	build [N]aive SSA form: don't replace local loads/stores with registers.
+I	build bare [I]nit functions: no init guards or calls to dependent inits.
+`
+
+func (m BuilderMode) String() string {
+	var buf bytes.Buffer
+	if m&GlobalDebug != 0 {
+		buf.WriteByte('D')
+	}
+	if m&PrintPackages != 0 {
+		buf.WriteByte('P')
+	}
+	if m&PrintFunctions != 0 {
+		buf.WriteByte('F')
+	}
+	if m&LogSource != 0 {
+		buf.WriteByte('S')
+	}
+	if m&SanityCheckFunctions != 0 {
+		buf.WriteByte('C')
+	}
+	if m&NaiveForm != 0 {
+		buf.WriteByte('N')
+	}
+	if m&BuildSerially != 0 {
+		buf.WriteByte('L')
+	}
+	return buf.String()
+}
+
+// Set parses the flag characters in s and updates *m.
+func (m *BuilderMode) Set(s string) error {
+	var mode BuilderMode
+	for _, c := range s {
+		switch c {
+		case 'D':
+			mode |= GlobalDebug
+		case 'P':
+			mode |= PrintPackages
+		case 'F':
+			mode |= PrintFunctions
+		case 'S':
+			mode |= LogSource | BuildSerially
+		case 'C':
+			mode |= SanityCheckFunctions
+		case 'N':
+			mode |= NaiveForm
+		case 'L':
+			mode |= BuildSerially
+		default:
+			return fmt.Errorf("unknown BuilderMode option: %q", c)
+		}
+	}
+	*m = mode
+	return nil
+}
+
+// Get returns m.
+func (m BuilderMode) Get() interface{} { return m }

vendor/honnef.co/go/tools/ssa/print.go

@@ -0,0 +1,435 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+// This file implements the String() methods for all Value and
+// Instruction types.
+
+import (
+	"bytes"
+	"fmt"
+	"go/types"
+	"io"
+	"reflect"
+	"sort"
+
+	"golang.org/x/tools/go/types/typeutil"
+)
+
+// relName returns the name of v relative to i.
+// In most cases, this is identical to v.Name(), but references to
+// Functions (including methods) and Globals use RelString and
+// all types are displayed with relType, so that only cross-package
+// references are package-qualified.
+//
+func relName(v Value, i Instruction) string {
+	var from *types.Package
+	if i != nil {
+		from = i.Parent().pkg()
+	}
+	switch v := v.(type) {
+	case Member: // *Function or *Global
+		return v.RelString(from)
+	case *Const:
+		return v.RelString(from)
+	}
+	return v.Name()
+}
+
+func relType(t types.Type, from *types.Package) string {
+	return types.TypeString(t, types.RelativeTo(from))
+}
+
+func relString(m Member, from *types.Package) string {
+	// NB: not all globals have an Object (e.g. init$guard),
+	// so use Package().Object not Object.Package().
+	if pkg := m.Package().Pkg; pkg != nil && pkg != from {
+		return fmt.Sprintf("%s.%s", pkg.Path(), m.Name())
+	}
+	return m.Name()
+}
+
+// Value.String()
+//
+// This method is provided only for debugging.
+// It never appears in disassembly, which uses Value.Name().
+
+func (v *Parameter) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("parameter %s : %s", v.Name(), relType(v.Type(), from))
+}
+
+func (v *FreeVar) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("freevar %s : %s", v.Name(), relType(v.Type(), from))
+}
+
+func (v *Builtin) String() string {
+	return fmt.Sprintf("builtin %s", v.Name())
+}
+
+// Instruction.String()
+
+func (v *Alloc) String() string {
+	op := "local"
+	if v.Heap {
+		op = "new"
+	}
+	from := v.Parent().pkg()
+	return fmt.Sprintf("%s %s (%s)", op, relType(deref(v.Type()), from), v.Comment)
+}
+
+func (v *Phi) String() string {
+	var b bytes.Buffer
+	b.WriteString("phi [")
+	for i, edge := range v.Edges {
+		if i > 0 {
+			b.WriteString(", ")
+		}
+		// Be robust against malformed CFG.
+		if v.block == nil {
+			b.WriteString("??")
+			continue
+		}
+		block := -1
+		if i < len(v.block.Preds) {
+			block = v.block.Preds[i].Index
+		}
+		fmt.Fprintf(&b, "%d: ", block)
+		edgeVal := "<nil>" // be robust
+		if edge != nil {
+			edgeVal = relName(edge, v)
+		}
+		b.WriteString(edgeVal)
+	}
+	b.WriteString("]")
+	if v.Comment != "" {
+		b.WriteString(" #")
+		b.WriteString(v.Comment)
+	}
+	return b.String()
+}
+
+func printCall(v *CallCommon, prefix string, instr Instruction) string {
+	var b bytes.Buffer
+	b.WriteString(prefix)
+	if !v.IsInvoke() {
+		b.WriteString(relName(v.Value, instr))
+	} else {
+		fmt.Fprintf(&b, "invoke %s.%s", relName(v.Value, instr), v.Method.Name())
+	}
+	b.WriteString("(")
+	for i, arg := range v.Args {
+		if i > 0 {
+			b.WriteString(", ")
+		}
+		b.WriteString(relName(arg, instr))
+	}
+	if v.Signature().Variadic() {
+		b.WriteString("...")
+	}
+	b.WriteString(")")
+	return b.String()
+}
+
+func (c *CallCommon) String() string {
+	return printCall(c, "", nil)
+}
+
+func (v *Call) String() string {
+	return printCall(&v.Call, "", v)
+}
+
+func (v *BinOp) String() string {
+	return fmt.Sprintf("%s %s %s", relName(v.X, v), v.Op.String(), relName(v.Y, v))
+}
+
+func (v *UnOp) String() string {
+	return fmt.Sprintf("%s%s%s", v.Op, relName(v.X, v), commaOk(v.CommaOk))
+}
+
+func printConv(prefix string, v, x Value) string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("%s %s <- %s (%s)",
+		prefix,
+		relType(v.Type(), from),
+		relType(x.Type(), from),
+		relName(x, v.(Instruction)))
+}
+
+func (v *ChangeType) String() string      { return printConv("changetype", v, v.X) }
+func (v *Convert) String() string         { return printConv("convert", v, v.X) }
+func (v *ChangeInterface) String() string { return printConv("change interface", v, v.X) }
+func (v *MakeInterface) String() string   { return printConv("make", v, v.X) }
+
+func (v *MakeClosure) String() string {
+	var b bytes.Buffer
+	fmt.Fprintf(&b, "make closure %s", relName(v.Fn, v))
+	if v.Bindings != nil {
+		b.WriteString(" [")
+		for i, c := range v.Bindings {
+			if i > 0 {
+				b.WriteString(", ")
+			}
+			b.WriteString(relName(c, v))
+		}
+		b.WriteString("]")
+	}
+	return b.String()
+}
+
+func (v *MakeSlice) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("make %s %s %s",
+		relType(v.Type(), from),
+		relName(v.Len, v),
+		relName(v.Cap, v))
+}
+
+func (v *Slice) String() string {
+	var b bytes.Buffer
+	b.WriteString("slice ")
+	b.WriteString(relName(v.X, v))
+	b.WriteString("[")
+	if v.Low != nil {
+		b.WriteString(relName(v.Low, v))
+	}
+	b.WriteString(":")
+	if v.High != nil {
+		b.WriteString(relName(v.High, v))
+	}
+	if v.Max != nil {
+		b.WriteString(":")
+		b.WriteString(relName(v.Max, v))
+	}
+	b.WriteString("]")
+	return b.String()
+}
+
+func (v *MakeMap) String() string {
+	res := ""
+	if v.Reserve != nil {
+		res = relName(v.Reserve, v)
+	}
+	from := v.Parent().pkg()
+	return fmt.Sprintf("make %s %s", relType(v.Type(), from), res)
+}
+
+func (v *MakeChan) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("make %s %s", relType(v.Type(), from), relName(v.Size, v))
+}
+
+func (v *FieldAddr) String() string {
+	st := deref(v.X.Type()).Underlying().(*types.Struct)
+	// Be robust against a bad index.
+	name := "?"
+	if 0 <= v.Field && v.Field < st.NumFields() {
+		name = st.Field(v.Field).Name()
+	}
+	return fmt.Sprintf("&%s.%s [#%d]", relName(v.X, v), name, v.Field)
+}
+
+func (v *Field) String() string {
+	st := v.X.Type().Underlying().(*types.Struct)
+	// Be robust against a bad index.
+	name := "?"
+	if 0 <= v.Field && v.Field < st.NumFields() {
+		name = st.Field(v.Field).Name()
+	}
+	return fmt.Sprintf("%s.%s [#%d]", relName(v.X, v), name, v.Field)
+}
+
+func (v *IndexAddr) String() string {
+	return fmt.Sprintf("&%s[%s]", relName(v.X, v), relName(v.Index, v))
+}
+
+func (v *Index) String() string {
+	return fmt.Sprintf("%s[%s]", relName(v.X, v), relName(v.Index, v))
+}
+
+func (v *Lookup) String() string {
+	return fmt.Sprintf("%s[%s]%s", relName(v.X, v), relName(v.Index, v), commaOk(v.CommaOk))
+}
+
+func (v *Range) String() string {
+	return "range " + relName(v.X, v)
+}
+
+func (v *Next) String() string {
+	return "next " + relName(v.Iter, v)
+}
+
+func (v *TypeAssert) String() string {
+	from := v.Parent().pkg()
+	return fmt.Sprintf("typeassert%s %s.(%s)", commaOk(v.CommaOk), relName(v.X, v), relType(v.AssertedType, from))
+}
+
+func (v *Extract) String() string {
+	return fmt.Sprintf("extract %s #%d", relName(v.Tuple, v), v.Index)
+}
+
+func (s *Jump) String() string {
+	// Be robust against malformed CFG.
+	block := -1
+	if s.block != nil && len(s.block.Succs) == 1 {
+		block = s.block.Succs[0].Index
+	}
+	return fmt.Sprintf("jump %d", block)
+}
+
+func (s *If) String() string {
+	// Be robust against malformed CFG.
+	tblock, fblock := -1, -1
+	if s.block != nil && len(s.block.Succs) == 2 {
+		tblock = s.block.Succs[0].Index
+		fblock = s.block.Succs[1].Index
+	}
+	return fmt.Sprintf("if %s goto %d else %d", relName(s.Cond, s), tblock, fblock)
+}
+
+func (s *Go) String() string {
+	return printCall(&s.Call, "go ", s)
+}
+
+func (s *Panic) String() string {
+	return "panic " + relName(s.X, s)
+}
+
+func (s *Return) String() string {
+	var b bytes.Buffer
+	b.WriteString("return")
+	for i, r := range s.Results {
+		if i == 0 {
+			b.WriteString(" ")
+		} else {
+			b.WriteString(", ")
+		}
+		b.WriteString(relName(r, s))
+	}
+	return b.String()
+}
+
+func (*RunDefers) String() string {
+	return "rundefers"
+}
+
+func (s *Send) String() string {
+	return fmt.Sprintf("send %s <- %s", relName(s.Chan, s), relName(s.X, s))
+}
+
+func (s *Defer) String() string {
+	return printCall(&s.Call, "defer ", s)
+}
+
+func (s *Select) String() string {
+	var b bytes.Buffer
+	for i, st := range s.States {
+		if i > 0 {
+			b.WriteString(", ")
+		}
+		if st.Dir == types.RecvOnly {
+			b.WriteString("<-")
+			b.WriteString(relName(st.Chan, s))
+		} else {
+			b.WriteString(relName(st.Chan, s))
+			b.WriteString("<-")
+			b.WriteString(relName(st.Send, s))
+		}
+	}
+	non := ""
+	if !s.Blocking {
+		non = "non"
+	}
+	return fmt.Sprintf("select %sblocking [%s]", non, b.String())
+}
+
+func (s *Store) String() string {
+	return fmt.Sprintf("*%s = %s", relName(s.Addr, s), relName(s.Val, s))
+}
+
+func (s *BlankStore) String() string {
+	return fmt.Sprintf("_ = %s", relName(s.Val, s))
+}
+
+func (s *MapUpdate) String() string {
+	return fmt.Sprintf("%s[%s] = %s", relName(s.Map, s), relName(s.Key, s), relName(s.Value, s))
+}
+
+func (s *DebugRef) String() string {
+	p := s.Parent().Prog.Fset.Position(s.Pos())
+	var descr interface{}
+	if s.object != nil {
+		descr = s.object // e.g. "var x int"
+	} else {
+		descr = reflect.TypeOf(s.Expr) // e.g. "*ast.CallExpr"
+	}
+	var addr string
+	if s.IsAddr {
+		addr = "address of "
+	}
+	return fmt.Sprintf("; %s%s @ %d:%d is %s", addr, descr, p.Line, p.Column, s.X.Name())
+}
+
+func (p *Package) String() string {
+	return "package " + p.Pkg.Path()
+}
+
+var _ io.WriterTo = (*Package)(nil) // *Package implements io.Writer
+
+func (p *Package) WriteTo(w io.Writer) (int64, error) {
+	var buf bytes.Buffer
+	WritePackage(&buf, p)
+	n, err := w.Write(buf.Bytes())
+	return int64(n), err
+}
+
+// WritePackage writes to buf a human-readable summary of p.
+func WritePackage(buf *bytes.Buffer, p *Package) {
+	fmt.Fprintf(buf, "%s:\n", p)
+
+	var names []string
+	maxname := 0
+	for name := range p.Members {
+		if l := len(name); l > maxname {
+			maxname = l
+		}
+		names = append(names, name)
+	}
+
+	from := p.Pkg
+	sort.Strings(names)
+	for _, name := range names {
+		switch mem := p.Members[name].(type) {
+		case *NamedConst:
+			fmt.Fprintf(buf, "  const %-*s %s = %s\n",
+				maxname, name, mem.Name(), mem.Value.RelString(from))
+
+		case *Function:
+			fmt.Fprintf(buf, "  func  %-*s %s\n",
+				maxname, name, relType(mem.Type(), from))
+
+		case *Type:
+			fmt.Fprintf(buf, "  type  %-*s %s\n",
+				maxname, name, relType(mem.Type().Underlying(), from))
+			for _, meth := range typeutil.IntuitiveMethodSet(mem.Type(), &p.Prog.MethodSets) {
+				fmt.Fprintf(buf, "    %s\n", types.SelectionString(meth, types.RelativeTo(from)))
+			}
+
+		case *Global:
+			fmt.Fprintf(buf, "  var   %-*s %s\n",
+				maxname, name, relType(mem.Type().(*types.Pointer).Elem(), from))
+		}
+	}
+
+	fmt.Fprintf(buf, "\n")
+}
+
+func commaOk(x bool) string {
+	if x {
+		return ",ok"
+	}
+	return ""
+}

vendor/honnef.co/go/tools/ssa/sanity.go

@@ -0,0 +1,523 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+// An optional pass for sanity-checking invariants of the SSA representation.
+// Currently it checks CFG invariants but little at the instruction level.
+
+import (
+	"fmt"
+	"go/types"
+	"io"
+	"os"
+	"strings"
+)
+
+type sanity struct {
+	reporter io.Writer
+	fn       *Function
+	block    *BasicBlock
+	instrs   map[Instruction]struct{}
+	insane   bool
+}
+
+// sanityCheck performs integrity checking of the SSA representation
+// of the function fn and returns true if it was valid.  Diagnostics
+// are written to reporter if non-nil, os.Stderr otherwise.  Some
+// diagnostics are only warnings and do not imply a negative result.
+//
+// Sanity-checking is intended to facilitate the debugging of code
+// transformation passes.
+//
+func sanityCheck(fn *Function, reporter io.Writer) bool {
+	if reporter == nil {
+		reporter = os.Stderr
+	}
+	return (&sanity{reporter: reporter}).checkFunction(fn)
+}
+
+// mustSanityCheck is like sanityCheck but panics instead of returning
+// a negative result.
+//
+func mustSanityCheck(fn *Function, reporter io.Writer) {
+	if !sanityCheck(fn, reporter) {
+		fn.WriteTo(os.Stderr)
+		panic("SanityCheck failed")
+	}
+}
+
+func (s *sanity) diagnostic(prefix, format string, args ...interface{}) {
+	fmt.Fprintf(s.reporter, "%s: function %s", prefix, s.fn)
+	if s.block != nil {
+		fmt.Fprintf(s.reporter, ", block %s", s.block)
+	}
+	io.WriteString(s.reporter, ": ")
+	fmt.Fprintf(s.reporter, format, args...)
+	io.WriteString(s.reporter, "\n")
+}
+
+func (s *sanity) errorf(format string, args ...interface{}) {
+	s.insane = true
+	s.diagnostic("Error", format, args...)
+}
+
+func (s *sanity) warnf(format string, args ...interface{}) {
+	s.diagnostic("Warning", format, args...)
+}
+
+// findDuplicate returns an arbitrary basic block that appeared more
+// than once in blocks, or nil if all were unique.
+func findDuplicate(blocks []*BasicBlock) *BasicBlock {
+	if len(blocks) < 2 {
+		return nil
+	}
+	if blocks[0] == blocks[1] {
+		return blocks[0]
+	}
+	// Slow path:
+	m := make(map[*BasicBlock]bool)
+	for _, b := range blocks {
+		if m[b] {
+			return b
+		}
+		m[b] = true
+	}
+	return nil
+}
+
+func (s *sanity) checkInstr(idx int, instr Instruction) {
+	switch instr := instr.(type) {
+	case *If, *Jump, *Return, *Panic:
+		s.errorf("control flow instruction not at end of block")
+	case *Phi:
+		if idx == 0 {
+			// It suffices to apply this check to just the first phi node.
+			if dup := findDuplicate(s.block.Preds); dup != nil {
+				s.errorf("phi node in block with duplicate predecessor %s", dup)
+			}
+		} else {
+			prev := s.block.Instrs[idx-1]
+			if _, ok := prev.(*Phi); !ok {
+				s.errorf("Phi instruction follows a non-Phi: %T", prev)
+			}
+		}
+		if ne, np := len(instr.Edges), len(s.block.Preds); ne != np {
+			s.errorf("phi node has %d edges but %d predecessors", ne, np)
+
+		} else {
+			for i, e := range instr.Edges {
+				if e == nil {
+					s.errorf("phi node '%s' has no value for edge #%d from %s", instr.Comment, i, s.block.Preds[i])
+				}
+			}
+		}
+
+	case *Alloc:
+		if !instr.Heap {
+			found := false
+			for _, l := range s.fn.Locals {
+				if l == instr {
+					found = true
+					break
+				}
+			}
+			if !found {
+				s.errorf("local alloc %s = %s does not appear in Function.Locals", instr.Name(), instr)
+			}
+		}
+
+	case *BinOp:
+	case *Call:
+	case *ChangeInterface:
+	case *ChangeType:
+	case *Convert:
+		if _, ok := instr.X.Type().Underlying().(*types.Basic); !ok {
+			if _, ok := instr.Type().Underlying().(*types.Basic); !ok {
+				s.errorf("convert %s -> %s: at least one type must be basic", instr.X.Type(), instr.Type())
+			}
+		}
+
+	case *Defer:
+	case *Extract:
+	case *Field:
+	case *FieldAddr:
+	case *Go:
+	case *Index:
+	case *IndexAddr:
+	case *Lookup:
+	case *MakeChan:
+	case *MakeClosure:
+		numFree := len(instr.Fn.(*Function).FreeVars)
+		numBind := len(instr.Bindings)
+		if numFree != numBind {
+			s.errorf("MakeClosure has %d Bindings for function %s with %d free vars",
+				numBind, instr.Fn, numFree)
+
+		}
+		if recv := instr.Type().(*types.Signature).Recv(); recv != nil {
+			s.errorf("MakeClosure's type includes receiver %s", recv.Type())
+		}
+
+	case *MakeInterface:
+	case *MakeMap:
+	case *MakeSlice:
+	case *MapUpdate:
+	case *Next:
+	case *Range:
+	case *RunDefers:
+	case *Select:
+	case *Send:
+	case *Slice:
+	case *Store:
+	case *TypeAssert:
+	case *UnOp:
+	case *DebugRef:
+	case *BlankStore:
+	case *Sigma:
+		// TODO(adonovan): implement checks.
+	default:
+		panic(fmt.Sprintf("Unknown instruction type: %T", instr))
+	}
+
+	if call, ok := instr.(CallInstruction); ok {
+		if call.Common().Signature() == nil {
+			s.errorf("nil signature: %s", call)
+		}
+	}
+
+	// Check that value-defining instructions have valid types
+	// and a valid referrer list.
+	if v, ok := instr.(Value); ok {
+		t := v.Type()
+		if t == nil {
+			s.errorf("no type: %s = %s", v.Name(), v)
+		} else if t == tRangeIter {
+			// not a proper type; ignore.
+		} else if b, ok := t.Underlying().(*types.Basic); ok && b.Info()&types.IsUntyped != 0 {
+			s.errorf("instruction has 'untyped' result: %s = %s : %s", v.Name(), v, t)
+		}
+		s.checkReferrerList(v)
+	}
+
+	// Untyped constants are legal as instruction Operands(),
+	// for example:
+	//   _ = "foo"[0]
+	// or:
+	//   if wordsize==64 {...}
+
+	// All other non-Instruction Values can be found via their
+	// enclosing Function or Package.
+}
+
+func (s *sanity) checkFinalInstr(instr Instruction) {
+	switch instr := instr.(type) {
+	case *If:
+		if nsuccs := len(s.block.Succs); nsuccs != 2 {
+			s.errorf("If-terminated block has %d successors; expected 2", nsuccs)
+			return
+		}
+		if s.block.Succs[0] == s.block.Succs[1] {
+			s.errorf("If-instruction has same True, False target blocks: %s", s.block.Succs[0])
+			return
+		}
+
+	case *Jump:
+		if nsuccs := len(s.block.Succs); nsuccs != 1 {
+			s.errorf("Jump-terminated block has %d successors; expected 1", nsuccs)
+			return
+		}
+
+	case *Return:
+		if nsuccs := len(s.block.Succs); nsuccs != 0 {
+			s.errorf("Return-terminated block has %d successors; expected none", nsuccs)
+			return
+		}
+		if na, nf := len(instr.Results), s.fn.Signature.Results().Len(); nf != na {
+			s.errorf("%d-ary return in %d-ary function", na, nf)
+		}
+
+	case *Panic:
+		if nsuccs := len(s.block.Succs); nsuccs != 0 {
+			s.errorf("Panic-terminated block has %d successors; expected none", nsuccs)
+			return
+		}
+
+	default:
+		s.errorf("non-control flow instruction at end of block")
+	}
+}
+
+func (s *sanity) checkBlock(b *BasicBlock, index int) {
+	s.block = b
+
+	if b.Index != index {
+		s.errorf("block has incorrect Index %d", b.Index)
+	}
+	if b.parent != s.fn {
+		s.errorf("block has incorrect parent %s", b.parent)
+	}
+
+	// Check all blocks are reachable.
+	// (The entry block is always implicitly reachable,
+	// as is the Recover block, if any.)
+	if (index > 0 && b != b.parent.Recover) && len(b.Preds) == 0 {
+		s.warnf("unreachable block")
+		if b.Instrs == nil {
+			// Since this block is about to be pruned,
+			// tolerating transient problems in it
+			// simplifies other optimizations.
+			return
+		}
+	}
+
+	// Check predecessor and successor relations are dual,
+	// and that all blocks in CFG belong to same function.
+	for _, a := range b.Preds {
+		found := false
+		for _, bb := range a.Succs {
+			if bb == b {
+				found = true
+				break
+			}
+		}
+		if !found {
+			s.errorf("expected successor edge in predecessor %s; found only: %s", a, a.Succs)
+		}
+		if a.parent != s.fn {
+			s.errorf("predecessor %s belongs to different function %s", a, a.parent)
+		}
+	}
+	for _, c := range b.Succs {
+		found := false
+		for _, bb := range c.Preds {
+			if bb == b {
+				found = true
+				break
+			}
+		}
+		if !found {
+			s.errorf("expected predecessor edge in successor %s; found only: %s", c, c.Preds)
+		}
+		if c.parent != s.fn {
+			s.errorf("successor %s belongs to different function %s", c, c.parent)
+		}
+	}
+
+	// Check each instruction is sane.
+	n := len(b.Instrs)
+	if n == 0 {
+		s.errorf("basic block contains no instructions")
+	}
+	var rands [10]*Value // reuse storage
+	for j, instr := range b.Instrs {
+		if instr == nil {
+			s.errorf("nil instruction at index %d", j)
+			continue
+		}
+		if b2 := instr.Block(); b2 == nil {
+			s.errorf("nil Block() for instruction at index %d", j)
+			continue
+		} else if b2 != b {
+			s.errorf("wrong Block() (%s) for instruction at index %d ", b2, j)
+			continue
+		}
+		if j < n-1 {
+			s.checkInstr(j, instr)
+		} else {
+			s.checkFinalInstr(instr)
+		}
+
+		// Check Instruction.Operands.
+	operands:
+		for i, op := range instr.Operands(rands[:0]) {
+			if op == nil {
+				s.errorf("nil operand pointer %d of %s", i, instr)
+				continue
+			}
+			val := *op
+			if val == nil {
+				continue // a nil operand is ok
+			}
+
+			// Check that "untyped" types only appear on constant operands.
+			if _, ok := (*op).(*Const); !ok {
+				if basic, ok := (*op).Type().(*types.Basic); ok {
+					if basic.Info()&types.IsUntyped != 0 {
+						s.errorf("operand #%d of %s is untyped: %s", i, instr, basic)
+					}
+				}
+			}
+
+			// Check that Operands that are also Instructions belong to same function.
+			// TODO(adonovan): also check their block dominates block b.
+			if val, ok := val.(Instruction); ok {
+				if val.Block() == nil {
+					s.errorf("operand %d of %s is an instruction (%s) that belongs to no block", i, instr, val)
+				} else if val.Parent() != s.fn {
+					s.errorf("operand %d of %s is an instruction (%s) from function %s", i, instr, val, val.Parent())
+				}
+			}
+
+			// Check that each function-local operand of
+			// instr refers back to instr.  (NB: quadratic)
+			switch val := val.(type) {
+			case *Const, *Global, *Builtin:
+				continue // not local
+			case *Function:
+				if val.parent == nil {
+					continue // only anon functions are local
+				}
+			}
+
+			// TODO(adonovan): check val.Parent() != nil <=> val.Referrers() is defined.
+
+			if refs := val.Referrers(); refs != nil {
+				for _, ref := range *refs {
+					if ref == instr {
+						continue operands
+					}
+				}
+				s.errorf("operand %d of %s (%s) does not refer to us", i, instr, val)
+			} else {
+				s.errorf("operand %d of %s (%s) has no referrers", i, instr, val)
+			}
+		}
+	}
+}
+
+func (s *sanity) checkReferrerList(v Value) {
+	refs := v.Referrers()
+	if refs == nil {
+		s.errorf("%s has missing referrer list", v.Name())
+		return
+	}
+	for i, ref := range *refs {
+		if _, ok := s.instrs[ref]; !ok {
+			s.errorf("%s.Referrers()[%d] = %s is not an instruction belonging to this function", v.Name(), i, ref)
+		}
+	}
+}
+
+func (s *sanity) checkFunction(fn *Function) bool {
+	// TODO(adonovan): check Function invariants:
+	// - check params match signature
+	// - check transient fields are nil
+	// - warn if any fn.Locals do not appear among block instructions.
+	s.fn = fn
+	if fn.Prog == nil {
+		s.errorf("nil Prog")
+	}
+
+	fn.String()            // must not crash
+	fn.RelString(fn.pkg()) // must not crash
+
+	// All functions have a package, except delegates (which are
+	// shared across packages, or duplicated as weak symbols in a
+	// separate-compilation model), and error.Error.
+	if fn.Pkg == nil {
+		if strings.HasPrefix(fn.Synthetic, "wrapper ") ||
+			strings.HasPrefix(fn.Synthetic, "bound ") ||
+			strings.HasPrefix(fn.Synthetic, "thunk ") ||
+			strings.HasSuffix(fn.name, "Error") {
+			// ok
+		} else {
+			s.errorf("nil Pkg")
+		}
+	}
+	if src, syn := fn.Synthetic == "", fn.Syntax() != nil; src != syn {
+		s.errorf("got fromSource=%t, hasSyntax=%t; want same values", src, syn)
+	}
+	for i, l := range fn.Locals {
+		if l.Parent() != fn {
+			s.errorf("Local %s at index %d has wrong parent", l.Name(), i)
+		}
+		if l.Heap {
+			s.errorf("Local %s at index %d has Heap flag set", l.Name(), i)
+		}
+	}
+	// Build the set of valid referrers.
+	s.instrs = make(map[Instruction]struct{})
+	for _, b := range fn.Blocks {
+		for _, instr := range b.Instrs {
+			s.instrs[instr] = struct{}{}
+		}
+	}
+	for i, p := range fn.Params {
+		if p.Parent() != fn {
+			s.errorf("Param %s at index %d has wrong parent", p.Name(), i)
+		}
+		s.checkReferrerList(p)
+	}
+	for i, fv := range fn.FreeVars {
+		if fv.Parent() != fn {
+			s.errorf("FreeVar %s at index %d has wrong parent", fv.Name(), i)
+		}
+		s.checkReferrerList(fv)
+	}
+
+	if fn.Blocks != nil && len(fn.Blocks) == 0 {
+		// Function _had_ blocks (so it's not external) but
+		// they were "optimized" away, even the entry block.
+		s.errorf("Blocks slice is non-nil but empty")
+	}
+	for i, b := range fn.Blocks {
+		if b == nil {
+			s.warnf("nil *BasicBlock at f.Blocks[%d]", i)
+			continue
+		}
+		s.checkBlock(b, i)
+	}
+	if fn.Recover != nil && fn.Blocks[fn.Recover.Index] != fn.Recover {
+		s.errorf("Recover block is not in Blocks slice")
+	}
+
+	s.block = nil
+	for i, anon := range fn.AnonFuncs {
+		if anon.Parent() != fn {
+			s.errorf("AnonFuncs[%d]=%s but %s.Parent()=%s", i, anon, anon, anon.Parent())
+		}
+	}
+	s.fn = nil
+	return !s.insane
+}
+
+// sanityCheckPackage checks invariants of packages upon creation.
+// It does not require that the package is built.
+// Unlike sanityCheck (for functions), it just panics at the first error.
+func sanityCheckPackage(pkg *Package) {
+	if pkg.Pkg == nil {
+		panic(fmt.Sprintf("Package %s has no Object", pkg))
+	}
+	pkg.String() // must not crash
+
+	for name, mem := range pkg.Members {
+		if name != mem.Name() {
+			panic(fmt.Sprintf("%s: %T.Name() = %s, want %s",
+				pkg.Pkg.Path(), mem, mem.Name(), name))
+		}
+		obj := mem.Object()
+		if obj == nil {
+			// This check is sound because fields
+			// {Global,Function}.object have type
+			// types.Object.  (If they were declared as
+			// *types.{Var,Func}, we'd have a non-empty
+			// interface containing a nil pointer.)
+
+			continue // not all members have typechecker objects
+		}
+		if obj.Name() != name {
+			if obj.Name() == "init" && strings.HasPrefix(mem.Name(), "init#") {
+				// Ok.  The name of a declared init function varies between
+				// its types.Func ("init") and its ssa.Function ("init#%d").
+			} else {
+				panic(fmt.Sprintf("%s: %T.Object().Name() = %s, want %s",
+					pkg.Pkg.Path(), mem, obj.Name(), name))
+			}
+		}
+		if obj.Pos() != mem.Pos() {
+			panic(fmt.Sprintf("%s Pos=%d obj.Pos=%d", mem, mem.Pos(), obj.Pos()))
+		}
+	}
+}

vendor/honnef.co/go/tools/ssa/source.go

@@ -0,0 +1,293 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+// This file defines utilities for working with source positions
+// or source-level named entities ("objects").
+
+// TODO(adonovan): test that {Value,Instruction}.Pos() positions match
+// the originating syntax, as specified.
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+)
+
+// EnclosingFunction returns the function that contains the syntax
+// node denoted by path.
+//
+// Syntax associated with package-level variable specifications is
+// enclosed by the package's init() function.
+//
+// Returns nil if not found; reasons might include:
+//    - the node is not enclosed by any function.
+//    - the node is within an anonymous function (FuncLit) and
+//      its SSA function has not been created yet
+//      (pkg.Build() has not yet been called).
+//
+func EnclosingFunction(pkg *Package, path []ast.Node) *Function {
+	// Start with package-level function...
+	fn := findEnclosingPackageLevelFunction(pkg, path)
+	if fn == nil {
+		return nil // not in any function
+	}
+
+	// ...then walk down the nested anonymous functions.
+	n := len(path)
+outer:
+	for i := range path {
+		if lit, ok := path[n-1-i].(*ast.FuncLit); ok {
+			for _, anon := range fn.AnonFuncs {
+				if anon.Pos() == lit.Type.Func {
+					fn = anon
+					continue outer
+				}
+			}
+			// SSA function not found:
+			// - package not yet built, or maybe
+			// - builder skipped FuncLit in dead block
+			//   (in principle; but currently the Builder
+			//   generates even dead FuncLits).
+			return nil
+		}
+	}
+	return fn
+}
+
+// HasEnclosingFunction returns true if the AST node denoted by path
+// is contained within the declaration of some function or
+// package-level variable.
+//
+// Unlike EnclosingFunction, the behaviour of this function does not
+// depend on whether SSA code for pkg has been built, so it can be
+// used to quickly reject check inputs that will cause
+// EnclosingFunction to fail, prior to SSA building.
+//
+func HasEnclosingFunction(pkg *Package, path []ast.Node) bool {
+	return findEnclosingPackageLevelFunction(pkg, path) != nil
+}
+
+// findEnclosingPackageLevelFunction returns the Function
+// corresponding to the package-level function enclosing path.
+//
+func findEnclosingPackageLevelFunction(pkg *Package, path []ast.Node) *Function {
+	if n := len(path); n >= 2 { // [... {Gen,Func}Decl File]
+		switch decl := path[n-2].(type) {
+		case *ast.GenDecl:
+			if decl.Tok == token.VAR && n >= 3 {
+				// Package-level 'var' initializer.
+				return pkg.init
+			}
+
+		case *ast.FuncDecl:
+			if decl.Recv == nil && decl.Name.Name == "init" {
+				// Explicit init() function.
+				for _, b := range pkg.init.Blocks {
+					for _, instr := range b.Instrs {
+						if instr, ok := instr.(*Call); ok {
+							if callee, ok := instr.Call.Value.(*Function); ok && callee.Pkg == pkg && callee.Pos() == decl.Name.NamePos {
+								return callee
+							}
+						}
+					}
+				}
+				// Hack: return non-nil when SSA is not yet
+				// built so that HasEnclosingFunction works.
+				return pkg.init
+			}
+			// Declared function/method.
+			return findNamedFunc(pkg, decl.Name.NamePos)
+		}
+	}
+	return nil // not in any function
+}
+
+// findNamedFunc returns the named function whose FuncDecl.Ident is at
+// position pos.
+//
+func findNamedFunc(pkg *Package, pos token.Pos) *Function {
+	// Look at all package members and method sets of named types.
+	// Not very efficient.
+	for _, mem := range pkg.Members {
+		switch mem := mem.(type) {
+		case *Function:
+			if mem.Pos() == pos {
+				return mem
+			}
+		case *Type:
+			mset := pkg.Prog.MethodSets.MethodSet(types.NewPointer(mem.Type()))
+			for i, n := 0, mset.Len(); i < n; i++ {
+				// Don't call Program.Method: avoid creating wrappers.
+				obj := mset.At(i).Obj().(*types.Func)
+				if obj.Pos() == pos {
+					return pkg.values[obj].(*Function)
+				}
+			}
+		}
+	}
+	return nil
+}
+
+// ValueForExpr returns the SSA Value that corresponds to non-constant
+// expression e.
+//
+// It returns nil if no value was found, e.g.
+//    - the expression is not lexically contained within f;
+//    - f was not built with debug information; or
+//    - e is a constant expression.  (For efficiency, no debug
+//      information is stored for constants. Use
+//      go/types.Info.Types[e].Value instead.)
+//    - e is a reference to nil or a built-in function.
+//    - the value was optimised away.
+//
+// If e is an addressable expression used in an lvalue context,
+// value is the address denoted by e, and isAddr is true.
+//
+// The types of e (or &e, if isAddr) and the result are equal
+// (modulo "untyped" bools resulting from comparisons).
+//
+// (Tip: to find the ssa.Value given a source position, use
+// importer.PathEnclosingInterval to locate the ast.Node, then
+// EnclosingFunction to locate the Function, then ValueForExpr to find
+// the ssa.Value.)
+//
+func (f *Function) ValueForExpr(e ast.Expr) (value Value, isAddr bool) {
+	if f.debugInfo() { // (opt)
+		e = unparen(e)
+		for _, b := range f.Blocks {
+			for _, instr := range b.Instrs {
+				if ref, ok := instr.(*DebugRef); ok {
+					if ref.Expr == e {
+						return ref.X, ref.IsAddr
+					}
+				}
+			}
+		}
+	}
+	return
+}
+
+// --- Lookup functions for source-level named entities (types.Objects) ---
+
+// Package returns the SSA Package corresponding to the specified
+// type-checker package object.
+// It returns nil if no such SSA package has been created.
+//
+func (prog *Program) Package(obj *types.Package) *Package {
+	return prog.packages[obj]
+}
+
+// packageLevelValue returns the package-level value corresponding to
+// the specified named object, which may be a package-level const
+// (*Const), var (*Global) or func (*Function) of some package in
+// prog.  It returns nil if the object is not found.
+//
+func (prog *Program) packageLevelValue(obj types.Object) Value {
+	if pkg, ok := prog.packages[obj.Pkg()]; ok {
+		return pkg.values[obj]
+	}
+	return nil
+}
+
+// FuncValue returns the concrete Function denoted by the source-level
+// named function obj, or nil if obj denotes an interface method.
+//
+// TODO(adonovan): check the invariant that obj.Type() matches the
+// result's Signature, both in the params/results and in the receiver.
+//
+func (prog *Program) FuncValue(obj *types.Func) *Function {
+	fn, _ := prog.packageLevelValue(obj).(*Function)
+	return fn
+}
+
+// ConstValue returns the SSA Value denoted by the source-level named
+// constant obj.
+//
+func (prog *Program) ConstValue(obj *types.Const) *Const {
+	// TODO(adonovan): opt: share (don't reallocate)
+	// Consts for const objects and constant ast.Exprs.
+
+	// Universal constant? {true,false,nil}
+	if obj.Parent() == types.Universe {
+		return NewConst(obj.Val(), obj.Type())
+	}
+	// Package-level named constant?
+	if v := prog.packageLevelValue(obj); v != nil {
+		return v.(*Const)
+	}
+	return NewConst(obj.Val(), obj.Type())
+}
+
+// VarValue returns the SSA Value that corresponds to a specific
+// identifier denoting the source-level named variable obj.
+//
+// VarValue returns nil if a local variable was not found, perhaps
+// because its package was not built, the debug information was not
+// requested during SSA construction, or the value was optimized away.
+//
+// ref is the path to an ast.Ident (e.g. from PathEnclosingInterval),
+// and that ident must resolve to obj.
+//
+// pkg is the package enclosing the reference.  (A reference to a var
+// always occurs within a function, so we need to know where to find it.)
+//
+// If the identifier is a field selector and its base expression is
+// non-addressable, then VarValue returns the value of that field.
+// For example:
+//    func f() struct {x int}
+//    f().x  // VarValue(x) returns a *Field instruction of type int
+//
+// All other identifiers denote addressable locations (variables).
+// For them, VarValue may return either the variable's address or its
+// value, even when the expression is evaluated only for its value; the
+// situation is reported by isAddr, the second component of the result.
+//
+// If !isAddr, the returned value is the one associated with the
+// specific identifier.  For example,
+//       var x int    // VarValue(x) returns Const 0 here
+//       x = 1        // VarValue(x) returns Const 1 here
+//
+// It is not specified whether the value or the address is returned in
+// any particular case, as it may depend upon optimizations performed
+// during SSA code generation, such as registerization, constant
+// folding, avoidance of materialization of subexpressions, etc.
+//
+func (prog *Program) VarValue(obj *types.Var, pkg *Package, ref []ast.Node) (value Value, isAddr bool) {
+	// All references to a var are local to some function, possibly init.
+	fn := EnclosingFunction(pkg, ref)
+	if fn == nil {
+		return // e.g. def of struct field; SSA not built?
+	}
+
+	id := ref[0].(*ast.Ident)
+
+	// Defining ident of a parameter?
+	if id.Pos() == obj.Pos() {
+		for _, param := range fn.Params {
+			if param.Object() == obj {
+				return param, false
+			}
+		}
+	}
+
+	// Other ident?
+	for _, b := range fn.Blocks {
+		for _, instr := range b.Instrs {
+			if dr, ok := instr.(*DebugRef); ok {
+				if dr.Pos() == id.Pos() {
+					return dr.X, dr.IsAddr
+				}
+			}
+		}
+	}
+
+	// Defining ident of package-level var?
+	if v := prog.packageLevelValue(obj); v != nil {
+		return v.(*Global), true
+	}
+
+	return // e.g. debug info not requested, or var optimized away
+}

vendor/honnef.co/go/tools/ssa/ssautil/load.go

@@ -0,0 +1,95 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssautil
+
+// This file defines utility functions for constructing programs in SSA form.
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+
+	"golang.org/x/tools/go/loader"
+	"honnef.co/go/tools/ssa"
+)
+
+// CreateProgram returns a new program in SSA form, given a program
+// loaded from source.  An SSA package is created for each transitively
+// error-free package of lprog.
+//
+// Code for bodies of functions is not built until Build is called
+// on the result.
+//
+// mode controls diagnostics and checking during SSA construction.
+//
+func CreateProgram(lprog *loader.Program, mode ssa.BuilderMode) *ssa.Program {
+	prog := ssa.NewProgram(lprog.Fset, mode)
+
+	for _, info := range lprog.AllPackages {
+		if info.TransitivelyErrorFree {
+			prog.CreatePackage(info.Pkg, info.Files, &info.Info, info.Importable)
+		}
+	}
+
+	return prog
+}
+
+// BuildPackage builds an SSA program with IR for a single package.
+//
+// It populates pkg by type-checking the specified file ASTs.  All
+// dependencies are loaded using the importer specified by tc, which
+// typically loads compiler export data; SSA code cannot be built for
+// those packages.  BuildPackage then constructs an ssa.Program with all
+// dependency packages created, and builds and returns the SSA package
+// corresponding to pkg.
+//
+// The caller must have set pkg.Path() to the import path.
+//
+// The operation fails if there were any type-checking or import errors.
+//
+// See ../ssa/example_test.go for an example.
+//
+func BuildPackage(tc *types.Config, fset *token.FileSet, pkg *types.Package, files []*ast.File, mode ssa.BuilderMode) (*ssa.Package, *types.Info, error) {
+	if fset == nil {
+		panic("no token.FileSet")
+	}
+	if pkg.Path() == "" {
+		panic("package has no import path")
+	}
+
+	info := &types.Info{
+		Types:      make(map[ast.Expr]types.TypeAndValue),
+		Defs:       make(map[*ast.Ident]types.Object),
+		Uses:       make(map[*ast.Ident]types.Object),
+		Implicits:  make(map[ast.Node]types.Object),
+		Scopes:     make(map[ast.Node]*types.Scope),
+		Selections: make(map[*ast.SelectorExpr]*types.Selection),
+	}
+	if err := types.NewChecker(tc, fset, pkg, info).Files(files); err != nil {
+		return nil, nil, err
+	}
+
+	prog := ssa.NewProgram(fset, mode)
+
+	// Create SSA packages for all imports.
+	// Order is not significant.
+	created := make(map[*types.Package]bool)
+	var createAll func(pkgs []*types.Package)
+	createAll = func(pkgs []*types.Package) {
+		for _, p := range pkgs {
+			if !created[p] {
+				created[p] = true
+				prog.CreatePackage(p, nil, nil, true)
+				createAll(p.Imports())
+			}
+		}
+	}
+	createAll(pkg.Imports())
+
+	// Create and build the primary package.
+	ssapkg := prog.CreatePackage(pkg, files, info, false)
+	ssapkg.Build()
+	return ssapkg, info, nil
+}

vendor/honnef.co/go/tools/ssa/ssautil/switch.go

@@ -0,0 +1,234 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssautil
+
+// This file implements discovery of switch and type-switch constructs
+// from low-level control flow.
+//
+// Many techniques exist for compiling a high-level switch with
+// constant cases to efficient machine code.  The optimal choice will
+// depend on the data type, the specific case values, the code in the
+// body of each case, and the hardware.
+// Some examples:
+// - a lookup table (for a switch that maps constants to constants)
+// - a computed goto
+// - a binary tree
+// - a perfect hash
+// - a two-level switch (to partition constant strings by their first byte).
+
+import (
+	"bytes"
+	"fmt"
+	"go/token"
+	"go/types"
+
+	"honnef.co/go/tools/ssa"
+)
+
+// A ConstCase represents a single constant comparison.
+// It is part of a Switch.
+type ConstCase struct {
+	Block *ssa.BasicBlock // block performing the comparison
+	Body  *ssa.BasicBlock // body of the case
+	Value *ssa.Const      // case comparand
+}
+
+// A TypeCase represents a single type assertion.
+// It is part of a Switch.
+type TypeCase struct {
+	Block   *ssa.BasicBlock // block performing the type assert
+	Body    *ssa.BasicBlock // body of the case
+	Type    types.Type      // case type
+	Binding ssa.Value       // value bound by this case
+}
+
+// A Switch is a logical high-level control flow operation
+// (a multiway branch) discovered by analysis of a CFG containing
+// only if/else chains.  It is not part of the ssa.Instruction set.
+//
+// One of ConstCases and TypeCases has length >= 2;
+// the other is nil.
+//
+// In a value switch, the list of cases may contain duplicate constants.
+// A type switch may contain duplicate types, or types assignable
+// to an interface type also in the list.
+// TODO(adonovan): eliminate such duplicates.
+//
+type Switch struct {
+	Start      *ssa.BasicBlock // block containing start of if/else chain
+	X          ssa.Value       // the switch operand
+	ConstCases []ConstCase     // ordered list of constant comparisons
+	TypeCases  []TypeCase      // ordered list of type assertions
+	Default    *ssa.BasicBlock // successor if all comparisons fail
+}
+
+func (sw *Switch) String() string {
+	// We represent each block by the String() of its
+	// first Instruction, e.g. "print(42:int)".
+	var buf bytes.Buffer
+	if sw.ConstCases != nil {
+		fmt.Fprintf(&buf, "switch %s {\n", sw.X.Name())
+		for _, c := range sw.ConstCases {
+			fmt.Fprintf(&buf, "case %s: %s\n", c.Value, c.Body.Instrs[0])
+		}
+	} else {
+		fmt.Fprintf(&buf, "switch %s.(type) {\n", sw.X.Name())
+		for _, c := range sw.TypeCases {
+			fmt.Fprintf(&buf, "case %s %s: %s\n",
+				c.Binding.Name(), c.Type, c.Body.Instrs[0])
+		}
+	}
+	if sw.Default != nil {
+		fmt.Fprintf(&buf, "default: %s\n", sw.Default.Instrs[0])
+	}
+	fmt.Fprintf(&buf, "}")
+	return buf.String()
+}
+
+// Switches examines the control-flow graph of fn and returns the
+// set of inferred value and type switches.  A value switch tests an
+// ssa.Value for equality against two or more compile-time constant
+// values.  Switches involving link-time constants (addresses) are
+// ignored.  A type switch type-asserts an ssa.Value against two or
+// more types.
+//
+// The switches are returned in dominance order.
+//
+// The resulting switches do not necessarily correspond to uses of the
+// 'switch' keyword in the source: for example, a single source-level
+// switch statement with non-constant cases may result in zero, one or
+// many Switches, one per plural sequence of constant cases.
+// Switches may even be inferred from if/else- or goto-based control flow.
+// (In general, the control flow constructs of the source program
+// cannot be faithfully reproduced from the SSA representation.)
+//
+func Switches(fn *ssa.Function) []Switch {
+	// Traverse the CFG in dominance order, so we don't
+	// enter an if/else-chain in the middle.
+	var switches []Switch
+	seen := make(map[*ssa.BasicBlock]bool) // TODO(adonovan): opt: use ssa.blockSet
+	for _, b := range fn.DomPreorder() {
+		if x, k := isComparisonBlock(b); x != nil {
+			// Block b starts a switch.
+			sw := Switch{Start: b, X: x}
+			valueSwitch(&sw, k, seen)
+			if len(sw.ConstCases) > 1 {
+				switches = append(switches, sw)
+			}
+		}
+
+		if y, x, T := isTypeAssertBlock(b); y != nil {
+			// Block b starts a type switch.
+			sw := Switch{Start: b, X: x}
+			typeSwitch(&sw, y, T, seen)
+			if len(sw.TypeCases) > 1 {
+				switches = append(switches, sw)
+			}
+		}
+	}
+	return switches
+}
+
+func valueSwitch(sw *Switch, k *ssa.Const, seen map[*ssa.BasicBlock]bool) {
+	b := sw.Start
+	x := sw.X
+	for x == sw.X {
+		if seen[b] {
+			break
+		}
+		seen[b] = true
+
+		sw.ConstCases = append(sw.ConstCases, ConstCase{
+			Block: b,
+			Body:  b.Succs[0],
+			Value: k,
+		})
+		b = b.Succs[1]
+		if len(b.Instrs) > 2 {
+			// Block b contains not just 'if x == k',
+			// so it may have side effects that
+			// make it unsafe to elide.
+			break
+		}
+		if len(b.Preds) != 1 {
+			// Block b has multiple predecessors,
+			// so it cannot be treated as a case.
+			break
+		}
+		x, k = isComparisonBlock(b)
+	}
+	sw.Default = b
+}
+
+func typeSwitch(sw *Switch, y ssa.Value, T types.Type, seen map[*ssa.BasicBlock]bool) {
+	b := sw.Start
+	x := sw.X
+	for x == sw.X {
+		if seen[b] {
+			break
+		}
+		seen[b] = true
+
+		sw.TypeCases = append(sw.TypeCases, TypeCase{
+			Block:   b,
+			Body:    b.Succs[0],
+			Type:    T,
+			Binding: y,
+		})
+		b = b.Succs[1]
+		if len(b.Instrs) > 4 {
+			// Block b contains not just
+			//  {TypeAssert; Extract #0; Extract #1; If}
+			// so it may have side effects that
+			// make it unsafe to elide.
+			break
+		}
+		if len(b.Preds) != 1 {
+			// Block b has multiple predecessors,
+			// so it cannot be treated as a case.
+			break
+		}
+		y, x, T = isTypeAssertBlock(b)
+	}
+	sw.Default = b
+}
+
+// isComparisonBlock returns the operands (v, k) if a block ends with
+// a comparison v==k, where k is a compile-time constant.
+//
+func isComparisonBlock(b *ssa.BasicBlock) (v ssa.Value, k *ssa.Const) {
+	if n := len(b.Instrs); n >= 2 {
+		if i, ok := b.Instrs[n-1].(*ssa.If); ok {
+			if binop, ok := i.Cond.(*ssa.BinOp); ok && binop.Block() == b && binop.Op == token.EQL {
+				if k, ok := binop.Y.(*ssa.Const); ok {
+					return binop.X, k
+				}
+				if k, ok := binop.X.(*ssa.Const); ok {
+					return binop.Y, k
+				}
+			}
+		}
+	}
+	return
+}
+
+// isTypeAssertBlock returns the operands (y, x, T) if a block ends with
+// a type assertion "if y, ok := x.(T); ok {".
+//
+func isTypeAssertBlock(b *ssa.BasicBlock) (y, x ssa.Value, T types.Type) {
+	if n := len(b.Instrs); n >= 4 {
+		if i, ok := b.Instrs[n-1].(*ssa.If); ok {
+			if ext1, ok := i.Cond.(*ssa.Extract); ok && ext1.Block() == b && ext1.Index == 1 {
+				if ta, ok := ext1.Tuple.(*ssa.TypeAssert); ok && ta.Block() == b {
+					// hack: relies upon instruction ordering.
+					if ext0, ok := b.Instrs[n-3].(*ssa.Extract); ok {
+						return ext0, ta.X, ta.AssertedType
+					}
+				}
+			}
+		}
+	}
+	return
+}

vendor/honnef.co/go/tools/ssa/ssautil/visit.go

@@ -0,0 +1,79 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssautil // import "honnef.co/go/tools/ssa/ssautil"
+
+import "honnef.co/go/tools/ssa"
+
+// This file defines utilities for visiting the SSA representation of
+// a Program.
+//
+// TODO(adonovan): test coverage.
+
+// AllFunctions finds and returns the set of functions potentially
+// needed by program prog, as determined by a simple linker-style
+// reachability algorithm starting from the members and method-sets of
+// each package.  The result may include anonymous functions and
+// synthetic wrappers.
+//
+// Precondition: all packages are built.
+//
+func AllFunctions(prog *ssa.Program) map[*ssa.Function]bool {
+	visit := visitor{
+		prog: prog,
+		seen: make(map[*ssa.Function]bool),
+	}
+	visit.program()
+	return visit.seen
+}
+
+type visitor struct {
+	prog *ssa.Program
+	seen map[*ssa.Function]bool
+}
+
+func (visit *visitor) program() {
+	for _, pkg := range visit.prog.AllPackages() {
+		for _, mem := range pkg.Members {
+			if fn, ok := mem.(*ssa.Function); ok {
+				visit.function(fn)
+			}
+		}
+	}
+	for _, T := range visit.prog.RuntimeTypes() {
+		mset := visit.prog.MethodSets.MethodSet(T)
+		for i, n := 0, mset.Len(); i < n; i++ {
+			visit.function(visit.prog.MethodValue(mset.At(i)))
+		}
+	}
+}
+
+func (visit *visitor) function(fn *ssa.Function) {
+	if !visit.seen[fn] {
+		visit.seen[fn] = true
+		var buf [10]*ssa.Value // avoid alloc in common case
+		for _, b := range fn.Blocks {
+			for _, instr := range b.Instrs {
+				for _, op := range instr.Operands(buf[:0]) {
+					if fn, ok := (*op).(*ssa.Function); ok {
+						visit.function(fn)
+					}
+				}
+			}
+		}
+	}
+}
+
+// MainPackages returns the subset of the specified packages
+// named "main" that define a main function.
+// The result may include synthetic "testmain" packages.
+func MainPackages(pkgs []*ssa.Package) []*ssa.Package {
+	var mains []*ssa.Package
+	for _, pkg := range pkgs {
+		if pkg.Pkg.Name() == "main" && pkg.Func("main") != nil {
+			mains = append(mains, pkg)
+		}
+	}
+	return mains
+}

vendor/honnef.co/go/tools/ssa/testmain.go

@@ -0,0 +1,267 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+// CreateTestMainPackage synthesizes a main package that runs all the
+// tests of the supplied packages.
+// It is closely coupled to $GOROOT/src/cmd/go/test.go and $GOROOT/src/testing.
+//
+// TODO(adonovan): this file no longer needs to live in the ssa package.
+// Move it to ssautil.
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/types"
+	"log"
+	"os"
+	"strings"
+	"text/template"
+)
+
+// FindTests returns the Test, Benchmark, and Example functions
+// (as defined by "go test") defined in the specified package,
+// and its TestMain function, if any.
+func FindTests(pkg *Package) (tests, benchmarks, examples []*Function, main *Function) {
+	prog := pkg.Prog
+
+	// The first two of these may be nil: if the program doesn't import "testing",
+	// it can't contain any tests, but it may yet contain Examples.
+	var testSig *types.Signature                              // func(*testing.T)
+	var benchmarkSig *types.Signature                         // func(*testing.B)
+	var exampleSig = types.NewSignature(nil, nil, nil, false) // func()
+
+	// Obtain the types from the parameters of testing.MainStart.
+	if testingPkg := prog.ImportedPackage("testing"); testingPkg != nil {
+		mainStart := testingPkg.Func("MainStart")
+		params := mainStart.Signature.Params()
+		testSig = funcField(params.At(1).Type())
+		benchmarkSig = funcField(params.At(2).Type())
+
+		// Does the package define this function?
+		//   func TestMain(*testing.M)
+		if f := pkg.Func("TestMain"); f != nil {
+			sig := f.Type().(*types.Signature)
+			starM := mainStart.Signature.Results().At(0).Type() // *testing.M
+			if sig.Results().Len() == 0 &&
+				sig.Params().Len() == 1 &&
+				types.Identical(sig.Params().At(0).Type(), starM) {
+				main = f
+			}
+		}
+	}
+
+	// TODO(adonovan): use a stable order, e.g. lexical.
+	for _, mem := range pkg.Members {
+		if f, ok := mem.(*Function); ok &&
+			ast.IsExported(f.Name()) &&
+			strings.HasSuffix(prog.Fset.Position(f.Pos()).Filename, "_test.go") {
+
+			switch {
+			case testSig != nil && isTestSig(f, "Test", testSig):
+				tests = append(tests, f)
+			case benchmarkSig != nil && isTestSig(f, "Benchmark", benchmarkSig):
+				benchmarks = append(benchmarks, f)
+			case isTestSig(f, "Example", exampleSig):
+				examples = append(examples, f)
+			default:
+				continue
+			}
+		}
+	}
+	return
+}
+
+// Like isTest, but checks the signature too.
+func isTestSig(f *Function, prefix string, sig *types.Signature) bool {
+	return isTest(f.Name(), prefix) && types.Identical(f.Signature, sig)
+}
+
+// Given the type of one of the three slice parameters of testing.Main,
+// returns the function type.
+func funcField(slice types.Type) *types.Signature {
+	return slice.(*types.Slice).Elem().Underlying().(*types.Struct).Field(1).Type().(*types.Signature)
+}
+
+// isTest tells whether name looks like a test (or benchmark, according to prefix).
+// It is a Test (say) if there is a character after Test that is not a lower-case letter.
+// We don't want TesticularCancer.
+// Plundered from $GOROOT/src/cmd/go/test.go
+func isTest(name, prefix string) bool {
+	if !strings.HasPrefix(name, prefix) {
+		return false
+	}
+	if len(name) == len(prefix) { // "Test" is ok
+		return true
+	}
+	return ast.IsExported(name[len(prefix):])
+}
+
+// CreateTestMainPackage creates and returns a synthetic "testmain"
+// package for the specified package if it defines tests, benchmarks or
+// executable examples, or nil otherwise.  The new package is named
+// "main" and provides a function named "main" that runs the tests,
+// similar to the one that would be created by the 'go test' tool.
+//
+// Subsequent calls to prog.AllPackages include the new package.
+// The package pkg must belong to the program prog.
+func (prog *Program) CreateTestMainPackage(pkg *Package) *Package {
+	if pkg.Prog != prog {
+		log.Fatal("Package does not belong to Program")
+	}
+
+	// Template data
+	var data struct {
+		Pkg                         *Package
+		Tests, Benchmarks, Examples []*Function
+		Main                        *Function
+		Go18                        bool
+	}
+	data.Pkg = pkg
+
+	// Enumerate tests.
+	data.Tests, data.Benchmarks, data.Examples, data.Main = FindTests(pkg)
+	if data.Main == nil &&
+		data.Tests == nil && data.Benchmarks == nil && data.Examples == nil {
+		return nil
+	}
+
+	// Synthesize source for testmain package.
+	path := pkg.Pkg.Path() + "$testmain"
+	tmpl := testmainTmpl
+	if testingPkg := prog.ImportedPackage("testing"); testingPkg != nil {
+		// In Go 1.8, testing.MainStart's first argument is an interface, not a func.
+		data.Go18 = types.IsInterface(testingPkg.Func("MainStart").Signature.Params().At(0).Type())
+	} else {
+		// The program does not import "testing", but FindTests
+		// returned non-nil, which must mean there were Examples
+		// but no Test, Benchmark, or TestMain functions.
+
+		// We'll simply call them from testmain.main; this will
+		// ensure they don't panic, but will not check any
+		// "Output:" comments.
+		// (We should not execute an Example that has no
+		// "Output:" comment, but it's impossible to tell here.)
+		tmpl = examplesOnlyTmpl
+	}
+	var buf bytes.Buffer
+	if err := tmpl.Execute(&buf, data); err != nil {
+		log.Fatalf("internal error expanding template for %s: %v", path, err)
+	}
+	if false { // debugging
+		fmt.Fprintln(os.Stderr, buf.String())
+	}
+
+	// Parse and type-check the testmain package.
+	f, err := parser.ParseFile(prog.Fset, path+".go", &buf, parser.Mode(0))
+	if err != nil {
+		log.Fatalf("internal error parsing %s: %v", path, err)
+	}
+	conf := types.Config{
+		DisableUnusedImportCheck: true,
+		Importer:                 importer{pkg},
+	}
+	files := []*ast.File{f}
+	info := &types.Info{
+		Types:      make(map[ast.Expr]types.TypeAndValue),
+		Defs:       make(map[*ast.Ident]types.Object),
+		Uses:       make(map[*ast.Ident]types.Object),
+		Implicits:  make(map[ast.Node]types.Object),
+		Scopes:     make(map[ast.Node]*types.Scope),
+		Selections: make(map[*ast.SelectorExpr]*types.Selection),
+	}
+	testmainPkg, err := conf.Check(path, prog.Fset, files, info)
+	if err != nil {
+		log.Fatalf("internal error type-checking %s: %v", path, err)
+	}
+
+	// Create and build SSA code.
+	testmain := prog.CreatePackage(testmainPkg, files, info, false)
+	testmain.SetDebugMode(false)
+	testmain.Build()
+	testmain.Func("main").Synthetic = "test main function"
+	testmain.Func("init").Synthetic = "package initializer"
+	return testmain
+}
+
+// An implementation of types.Importer for an already loaded SSA program.
+type importer struct {
+	pkg *Package // package under test; may be non-importable
+}
+
+func (imp importer) Import(path string) (*types.Package, error) {
+	if p := imp.pkg.Prog.ImportedPackage(path); p != nil {
+		return p.Pkg, nil
+	}
+	if path == imp.pkg.Pkg.Path() {
+		return imp.pkg.Pkg, nil
+	}
+	return nil, fmt.Errorf("not found") // can't happen
+}
+
+var testmainTmpl = template.Must(template.New("testmain").Parse(`
+package main
+
+import "io"
+import "os"
+import "testing"
+import p {{printf "%q" .Pkg.Pkg.Path}}
+
+{{if .Go18}}
+type deps struct{}
+
+func (deps) ImportPath() string { return "" }
+func (deps) MatchString(pat, str string) (bool, error) { return true, nil }
+func (deps) StartCPUProfile(io.Writer) error { return nil }
+func (deps) StartTestLog(io.Writer) {}
+func (deps) StopCPUProfile() {}
+func (deps) StopTestLog() error { return nil }
+func (deps) WriteHeapProfile(io.Writer) error { return nil }
+func (deps) WriteProfileTo(string, io.Writer, int) error { return nil }
+
+var match deps
+{{else}}
+func match(_, _ string) (bool, error) { return true, nil }
+{{end}}
+
+func main() {
+	tests := []testing.InternalTest{
+{{range .Tests}}
+		{ {{printf "%q" .Name}}, p.{{.Name}} },
+{{end}}
+	}
+	benchmarks := []testing.InternalBenchmark{
+{{range .Benchmarks}}
+		{ {{printf "%q" .Name}}, p.{{.Name}} },
+{{end}}
+	}
+	examples := []testing.InternalExample{
+{{range .Examples}}
+		{Name: {{printf "%q" .Name}}, F: p.{{.Name}}},
+{{end}}
+	}
+	m := testing.MainStart(match, tests, benchmarks, examples)
+{{with .Main}}
+	p.{{.Name}}(m)
+{{else}}
+	os.Exit(m.Run())
+{{end}}
+}
+
+`))
+
+var examplesOnlyTmpl = template.Must(template.New("examples").Parse(`
+package main
+
+import p {{printf "%q" .Pkg.Pkg.Path}}
+
+func main() {
+{{range .Examples}}
+	p.{{.Name}}()
+{{end}}
+}
+`))

vendor/honnef.co/go/tools/ssa/util.go

@@ -0,0 +1,119 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+// This file defines a number of miscellaneous utility functions.
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"go/types"
+	"io"
+	"os"
+
+	"golang.org/x/tools/go/ast/astutil"
+)
+
+//// AST utilities
+
+func unparen(e ast.Expr) ast.Expr { return astutil.Unparen(e) }
+
+// isBlankIdent returns true iff e is an Ident with name "_".
+// They have no associated types.Object, and thus no type.
+//
+func isBlankIdent(e ast.Expr) bool {
+	id, ok := e.(*ast.Ident)
+	return ok && id.Name == "_"
+}
+
+//// Type utilities.  Some of these belong in go/types.
+
+// isPointer returns true for types whose underlying type is a pointer.
+func isPointer(typ types.Type) bool {
+	_, ok := typ.Underlying().(*types.Pointer)
+	return ok
+}
+
+func isInterface(T types.Type) bool { return types.IsInterface(T) }
+
+// deref returns a pointer's element type; otherwise it returns typ.
+func deref(typ types.Type) types.Type {
+	if p, ok := typ.Underlying().(*types.Pointer); ok {
+		return p.Elem()
+	}
+	return typ
+}
+
+// recvType returns the receiver type of method obj.
+func recvType(obj *types.Func) types.Type {
+	return obj.Type().(*types.Signature).Recv().Type()
+}
+
+// DefaultType returns the default "typed" type for an "untyped" type;
+// it returns the incoming type for all other types.  The default type
+// for untyped nil is untyped nil.
+//
+// Exported to ssa/interp.
+//
+// TODO(adonovan): use go/types.DefaultType after 1.8.
+//
+func DefaultType(typ types.Type) types.Type {
+	if t, ok := typ.(*types.Basic); ok {
+		k := t.Kind()
+		switch k {
+		case types.UntypedBool:
+			k = types.Bool
+		case types.UntypedInt:
+			k = types.Int
+		case types.UntypedRune:
+			k = types.Rune
+		case types.UntypedFloat:
+			k = types.Float64
+		case types.UntypedComplex:
+			k = types.Complex128
+		case types.UntypedString:
+			k = types.String
+		}
+		typ = types.Typ[k]
+	}
+	return typ
+}
+
+// logStack prints the formatted "start" message to stderr and
+// returns a closure that prints the corresponding "end" message.
+// Call using 'defer logStack(...)()' to show builder stack on panic.
+// Don't forget trailing parens!
+//
+func logStack(format string, args ...interface{}) func() {
+	msg := fmt.Sprintf(format, args...)
+	io.WriteString(os.Stderr, msg)
+	io.WriteString(os.Stderr, "\n")
+	return func() {
+		io.WriteString(os.Stderr, msg)
+		io.WriteString(os.Stderr, " end\n")
+	}
+}
+
+// newVar creates a 'var' for use in a types.Tuple.
+func newVar(name string, typ types.Type) *types.Var {
+	return types.NewParam(token.NoPos, nil, name, typ)
+}
+
+// anonVar creates an anonymous 'var' for use in a types.Tuple.
+func anonVar(typ types.Type) *types.Var {
+	return newVar("", typ)
+}
+
+var lenResults = types.NewTuple(anonVar(tInt))
+
+// makeLen returns the len builtin specialized to type func(T)int.
+func makeLen(T types.Type) *Builtin {
+	lenParams := types.NewTuple(anonVar(T))
+	return &Builtin{
+		name: "len",
+		sig:  types.NewSignature(nil, lenParams, lenResults, false),
+	}
+}

vendor/honnef.co/go/tools/ssa/wrappers.go

@@ -0,0 +1,294 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+// This file defines synthesis of Functions that delegate to declared
+// methods; they come in three kinds:
+//
+// (1) wrappers: methods that wrap declared methods, performing
+//     implicit pointer indirections and embedded field selections.
+//
+// (2) thunks: funcs that wrap declared methods.  Like wrappers,
+//     thunks perform indirections and field selections. The thunk's
+//     first parameter is used as the receiver for the method call.
+//
+// (3) bounds: funcs that wrap declared methods.  The bound's sole
+//     free variable, supplied by a closure, is used as the receiver
+//     for the method call.  No indirections or field selections are
+//     performed since they can be done before the call.
+
+import (
+	"fmt"
+
+	"go/types"
+)
+
+// -- wrappers -----------------------------------------------------------
+
+// makeWrapper returns a synthetic method that delegates to the
+// declared method denoted by meth.Obj(), first performing any
+// necessary pointer indirections or field selections implied by meth.
+//
+// The resulting method's receiver type is meth.Recv().
+//
+// This function is versatile but quite subtle!  Consider the
+// following axes of variation when making changes:
+//   - optional receiver indirection
+//   - optional implicit field selections
+//   - meth.Obj() may denote a concrete or an interface method
+//   - the result may be a thunk or a wrapper.
+//
+// EXCLUSIVE_LOCKS_REQUIRED(prog.methodsMu)
+//
+func makeWrapper(prog *Program, sel *types.Selection) *Function {
+	obj := sel.Obj().(*types.Func)       // the declared function
+	sig := sel.Type().(*types.Signature) // type of this wrapper
+
+	var recv *types.Var // wrapper's receiver or thunk's params[0]
+	name := obj.Name()
+	var description string
+	var start int // first regular param
+	if sel.Kind() == types.MethodExpr {
+		name += "$thunk"
+		description = "thunk"
+		recv = sig.Params().At(0)
+		start = 1
+	} else {
+		description = "wrapper"
+		recv = sig.Recv()
+	}
+
+	description = fmt.Sprintf("%s for %s", description, sel.Obj())
+	if prog.mode&LogSource != 0 {
+		defer logStack("make %s to (%s)", description, recv.Type())()
+	}
+	fn := &Function{
+		name:      name,
+		method:    sel,
+		object:    obj,
+		Signature: sig,
+		Synthetic: description,
+		Prog:      prog,
+		pos:       obj.Pos(),
+	}
+	fn.startBody()
+	fn.addSpilledParam(recv)
+	createParams(fn, start)
+
+	indices := sel.Index()
+
+	var v Value = fn.Locals[0] // spilled receiver
+	if isPointer(sel.Recv()) {
+		v = emitLoad(fn, v)
+
+		// For simple indirection wrappers, perform an informative nil-check:
+		// "value method (T).f called using nil *T pointer"
+		if len(indices) == 1 && !isPointer(recvType(obj)) {
+			var c Call
+			c.Call.Value = &Builtin{
+				name: "ssa:wrapnilchk",
+				sig: types.NewSignature(nil,
+					types.NewTuple(anonVar(sel.Recv()), anonVar(tString), anonVar(tString)),
+					types.NewTuple(anonVar(sel.Recv())), false),
+			}
+			c.Call.Args = []Value{
+				v,
+				stringConst(deref(sel.Recv()).String()),
+				stringConst(sel.Obj().Name()),
+			}
+			c.setType(v.Type())
+			v = fn.emit(&c)
+		}
+	}
+
+	// Invariant: v is a pointer, either
+	//   value of *A receiver param, or
+	// address of  A spilled receiver.
+
+	// We use pointer arithmetic (FieldAddr possibly followed by
+	// Load) in preference to value extraction (Field possibly
+	// preceded by Load).
+
+	v = emitImplicitSelections(fn, v, indices[:len(indices)-1])
+
+	// Invariant: v is a pointer, either
+	//   value of implicit *C field, or
+	// address of implicit  C field.
+
+	var c Call
+	if r := recvType(obj); !isInterface(r) { // concrete method
+		if !isPointer(r) {
+			v = emitLoad(fn, v)
+		}
+		c.Call.Value = prog.declaredFunc(obj)
+		c.Call.Args = append(c.Call.Args, v)
+	} else {
+		c.Call.Method = obj
+		c.Call.Value = emitLoad(fn, v)
+	}
+	for _, arg := range fn.Params[1:] {
+		c.Call.Args = append(c.Call.Args, arg)
+	}
+	emitTailCall(fn, &c)
+	fn.finishBody()
+	return fn
+}
+
+// createParams creates parameters for wrapper method fn based on its
+// Signature.Params, which do not include the receiver.
+// start is the index of the first regular parameter to use.
+//
+func createParams(fn *Function, start int) {
+	var last *Parameter
+	tparams := fn.Signature.Params()
+	for i, n := start, tparams.Len(); i < n; i++ {
+		last = fn.addParamObj(tparams.At(i))
+	}
+	if fn.Signature.Variadic() {
+		last.typ = types.NewSlice(last.typ)
+	}
+}
+
+// -- bounds -----------------------------------------------------------
+
+// makeBound returns a bound method wrapper (or "bound"), a synthetic
+// function that delegates to a concrete or interface method denoted
+// by obj.  The resulting function has no receiver, but has one free
+// variable which will be used as the method's receiver in the
+// tail-call.
+//
+// Use MakeClosure with such a wrapper to construct a bound method
+// closure.  e.g.:
+//
+//   type T int          or:  type T interface { meth() }
+//   func (t T) meth()
+//   var t T
+//   f := t.meth
+//   f() // calls t.meth()
+//
+// f is a closure of a synthetic wrapper defined as if by:
+//
+//   f := func() { return t.meth() }
+//
+// Unlike makeWrapper, makeBound need perform no indirection or field
+// selections because that can be done before the closure is
+// constructed.
+//
+// EXCLUSIVE_LOCKS_ACQUIRED(meth.Prog.methodsMu)
+//
+func makeBound(prog *Program, obj *types.Func) *Function {
+	prog.methodsMu.Lock()
+	defer prog.methodsMu.Unlock()
+	fn, ok := prog.bounds[obj]
+	if !ok {
+		description := fmt.Sprintf("bound method wrapper for %s", obj)
+		if prog.mode&LogSource != 0 {
+			defer logStack("%s", description)()
+		}
+		fn = &Function{
+			name:      obj.Name() + "$bound",
+			object:    obj,
+			Signature: changeRecv(obj.Type().(*types.Signature), nil), // drop receiver
+			Synthetic: description,
+			Prog:      prog,
+			pos:       obj.Pos(),
+		}
+
+		fv := &FreeVar{name: "recv", typ: recvType(obj), parent: fn}
+		fn.FreeVars = []*FreeVar{fv}
+		fn.startBody()
+		createParams(fn, 0)
+		var c Call
+
+		if !isInterface(recvType(obj)) { // concrete
+			c.Call.Value = prog.declaredFunc(obj)
+			c.Call.Args = []Value{fv}
+		} else {
+			c.Call.Value = fv
+			c.Call.Method = obj
+		}
+		for _, arg := range fn.Params {
+			c.Call.Args = append(c.Call.Args, arg)
+		}
+		emitTailCall(fn, &c)
+		fn.finishBody()
+
+		prog.bounds[obj] = fn
+	}
+	return fn
+}
+
+// -- thunks -----------------------------------------------------------
+
+// makeThunk returns a thunk, a synthetic function that delegates to a
+// concrete or interface method denoted by sel.Obj().  The resulting
+// function has no receiver, but has an additional (first) regular
+// parameter.
+//
+// Precondition: sel.Kind() == types.MethodExpr.
+//
+//   type T int          or:  type T interface { meth() }
+//   func (t T) meth()
+//   f := T.meth
+//   var t T
+//   f(t) // calls t.meth()
+//
+// f is a synthetic wrapper defined as if by:
+//
+//   f := func(t T) { return t.meth() }
+//
+// TODO(adonovan): opt: currently the stub is created even when used
+// directly in a function call: C.f(i, 0).  This is less efficient
+// than inlining the stub.
+//
+// EXCLUSIVE_LOCKS_ACQUIRED(meth.Prog.methodsMu)
+//
+func makeThunk(prog *Program, sel *types.Selection) *Function {
+	if sel.Kind() != types.MethodExpr {
+		panic(sel)
+	}
+
+	key := selectionKey{
+		kind:     sel.Kind(),
+		recv:     sel.Recv(),
+		obj:      sel.Obj(),
+		index:    fmt.Sprint(sel.Index()),
+		indirect: sel.Indirect(),
+	}
+
+	prog.methodsMu.Lock()
+	defer prog.methodsMu.Unlock()
+
+	// Canonicalize key.recv to avoid constructing duplicate thunks.
+	canonRecv, ok := prog.canon.At(key.recv).(types.Type)
+	if !ok {
+		canonRecv = key.recv
+		prog.canon.Set(key.recv, canonRecv)
+	}
+	key.recv = canonRecv
+
+	fn, ok := prog.thunks[key]
+	if !ok {
+		fn = makeWrapper(prog, sel)
+		if fn.Signature.Recv() != nil {
+			panic(fn) // unexpected receiver
+		}
+		prog.thunks[key] = fn
+	}
+	return fn
+}
+
+func changeRecv(s *types.Signature, recv *types.Var) *types.Signature {
+	return types.NewSignature(recv, s.Params(), s.Results(), s.Variadic())
+}
+
+// selectionKey is like types.Selection but a usable map key.
+type selectionKey struct {
+	kind     types.SelectionKind
+	recv     types.Type // canonicalized via Program.canon
+	obj      types.Object
+	index    string
+	indirect bool
+}

vendor/honnef.co/go/tools/ssa/write.go

@@ -0,0 +1,5 @@
+package ssa
+
+func NewJump(parent *BasicBlock) *Jump {
+	return &Jump{anInstruction{parent}}
+}

vendor/honnef.co/go/tools/version/version.go

@@ -0,0 +1,17 @@
+package version
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+const Version = "devel"
+
+func Print() {
+	if Version == "devel" {
+		fmt.Printf("%s (no version)\n", filepath.Base(os.Args[0]))
+	} else {
+		fmt.Printf("%s %s\n", filepath.Base(os.Args[0]), Version)
+	}
+}

vendor/modules.txt

@@ -72,8 +72,14 @@ github.com/hashicorp/hcl/json/scanner
 github.com/hashicorp/hcl/json/token
 # github.com/imdario/mergo v0.3.6
 github.com/imdario/mergo
+# github.com/jgautheron/goconst v0.0.0-20170703170152-9740945f5dcb
+github.com/jgautheron/goconst/cmd/goconst
+github.com/jgautheron/goconst
 # github.com/karalabe/xgo v0.0.0-20181007145344-72da7d1d3970
 github.com/karalabe/xgo
+# github.com/kisielk/gotool v1.0.0
+github.com/kisielk/gotool
+github.com/kisielk/gotool/internal/load
 # github.com/labstack/echo v3.3.5+incompatible
 github.com/labstack/echo
 github.com/labstack/echo/middleware
@@ -174,6 +180,7 @@ golang.org/x/text/unicode/bidi
 golang.org/x/tools/go/loader
 golang.org/x/tools/go/ast/astutil
 golang.org/x/tools/go/gcexportdata
+golang.org/x/tools/go/types/typeutil
 golang.org/x/tools/go/buildutil
 golang.org/x/tools/go/internal/cgo
 golang.org/x/tools/go/internal/gcimporter
@@ -187,3 +194,15 @@ gopkg.in/gomail.v2
 gopkg.in/testfixtures.v2
 # gopkg.in/yaml.v2 v2.2.2
 gopkg.in/yaml.v2
+# honnef.co/go/tools v0.0.0-20180920025451-e3ad64cb4ed3
+honnef.co/go/tools/cmd/gosimple
+honnef.co/go/tools/cmd/unused
+honnef.co/go/tools/lint/lintutil
+honnef.co/go/tools/simple
+honnef.co/go/tools/unused
+honnef.co/go/tools/lint
+honnef.co/go/tools/version
+honnef.co/go/tools/internal/sharedcheck
+honnef.co/go/tools/lint/lintdsl
+honnef.co/go/tools/ssa
+honnef.co/go/tools/ssa/ssautil