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go/build: prefer //go:build over // +build lines

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Part of //go:build change (#41184).
See https://golang.org/design/draft-gobuild

- Reject files with multiple //go:build lines.
- If a file has both //go:build and // +build lines, only use the //go:build line.
- Otherwise fall back to // +build lines
- Use go/build/constraint for parsing both //go:build and // +build lines.

For Go 1.17.

Change-Id: I32e2404d8ce266230f767718dc7cc24e77b425e8
Reviewed-on: https://go-review.googlesource.com/c/go/+/240607
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>
This commit is contained in:
Russ Cox 2020-06-22 13:27:10 -04:00
parent a8942d2cff
commit 5b76343a10
3 changed files with 129 additions and 104 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

139
src/go/build/build.go
View File

@ -9,6 +9,7 @@ import (
"errors"
"fmt"
"go/ast"
"go/build/constraint"
"go/doc"
"go/token"
exec "internal/execabs"
@ -1423,7 +1424,7 @@ func (ctxt *Context) matchFile(dir, name string, allTags map[string]bool, binary
// Look for +build comments to accept or reject the file.
ok, sawBinaryOnly, err := ctxt.shouldBuild(info.header, allTags)
if err != nil {
return nil, err
return nil, fmt.Errorf("%s: %v", name, err)
}
if !ok && !ctxt.UseAllFiles {
return nil, nil
@ -1459,11 +1460,12 @@ var (
bSlashSlash = []byte(slashSlash)
bStarSlash = []byte(starSlash)
bSlashStar = []byte(slashStar)
bPlusBuild = []byte("+build")
goBuildComment = []byte("//go:build")
errGoBuildWithoutBuild = errors.New("//go:build comment without // +build comment")
errMultipleGoBuild = errors.New("multiple //go:build comments") // unused in Go 1.(N-1)
errMultipleGoBuild = errors.New("multiple //go:build comments")
)
func isGoBuildComment(line []byte) bool {
@ -1498,8 +1500,7 @@ var binaryOnlyComment = []byte("//go:binary-only-package")
// shouldBuild reports whether the file should be built
// and whether a //go:binary-only-package comment was found.
func (ctxt *Context) shouldBuild(content []byte, allTags map[string]bool) (shouldBuild, binaryOnly bool, err error) {
// Pass 1. Identify leading run of // comments and blank lines,
// Identify leading run of // comments and blank lines,
// which must be followed by a blank line.
// Also identify any //go:build comments.
content, goBuild, sawBinaryOnly, err := parseFileHeader(content)
@ -1507,44 +1508,42 @@ func (ctxt *Context) shouldBuild(content []byte, allTags map[string]bool) (shoul
return false, false, err
}
// Pass 2. Process each +build line in the run.
p := content
shouldBuild = true
sawBuild := false
for len(p) > 0 {
line := p
if i := bytes.IndexByte(line, '\n'); i >= 0 {
line, p = line[:i], p[i+1:]
} else {
p = p[len(p):]
// If //go:build line is present, it controls.
// Otherwise fall back to +build processing.
switch {
case goBuild != nil:
x, err := constraint.Parse(string(goBuild))
if err != nil {
return false, false, fmt.Errorf("parsing //go:build line: %v", err)
}
line = bytes.TrimSpace(line)
if !bytes.HasPrefix(line, bSlashSlash) {
continue
}
line = bytes.TrimSpace(line[len(bSlashSlash):])
if len(line) > 0 && line[0] == '+' {
// Looks like a comment +line.
f := strings.Fields(string(line))
if f[0] == "+build" {
sawBuild = true
ok := false
for _, tok := range f[1:] {
if ctxt.match(tok, allTags) {
ok = true
}
}
if !ok {
shouldBuild = ctxt.eval(x, allTags)
default:
shouldBuild = true
p := content
for len(p) > 0 {
line := p
if i := bytes.IndexByte(line, '\n'); i >= 0 {
line, p = line[:i], p[i+1:]
} else {
p = p[len(p):]
}
line = bytes.TrimSpace(line)
if !bytes.HasPrefix(line, bSlashSlash) || !bytes.Contains(line, bPlusBuild) {
continue
}
text := string(line)
if !constraint.IsPlusBuild(text) {
continue
}
if x, err := constraint.Parse(text); err == nil {
if !ctxt.eval(x, allTags) {
shouldBuild = false
}
}
}
}
if goBuild != nil && !sawBuild {
return false, false, errGoBuildWithoutBuild
}
return shouldBuild, sawBinaryOnly, nil
}
@ -1580,7 +1579,7 @@ Lines:
}
if !inSlashStar && isGoBuildComment(line) {
if false && goBuild != nil { // enabled in Go 1.N
if goBuild != nil {
return nil, nil, false, errMultipleGoBuild
}
goBuild = line
@ -1649,7 +1648,7 @@ func (ctxt *Context) saveCgo(filename string, di *Package, cg *ast.CommentGroup)
if len(cond) > 0 {
ok := false
for _, c := range cond {
if ctxt.match(c, nil) {
if ctxt.matchAuto(c, nil) {
ok = true
break
}
@ -1831,50 +1830,44 @@ func splitQuoted(s string) (r []string, err error) {
return args, err
}
// match reports whether the name is one of:
// matchAuto interprets text as either a +build or //go:build expression (whichever works),
// reporting whether the expression matches the build context.
//
// matchAuto is only used for testing of tag evaluation
// and in #cgo lines, which accept either syntax.
func (ctxt *Context) matchAuto(text string, allTags map[string]bool) bool {
if strings.ContainsAny(text, "&|()") {
text = "//go:build " + text
} else {
text = "// +build " + text
}
x, err := constraint.Parse(text)
if err != nil {
return false
}
return ctxt.eval(x, allTags)
}
func (ctxt *Context) eval(x constraint.Expr, allTags map[string]bool) bool {
return x.Eval(func(tag string) bool { return ctxt.matchTag(tag, allTags) })
}
// matchTag reports whether the name is one of:
//
// cgo (if cgo is enabled)
// $GOOS
// $GOARCH
// cgo (if cgo is enabled)
// !cgo (if cgo is disabled)
// ctxt.Compiler
// !ctxt.Compiler
// linux (if GOOS = android)
// solaris (if GOOS = illumos)
// tag (if tag is listed in ctxt.BuildTags or ctxt.ReleaseTags)
// !tag (if tag is not listed in ctxt.BuildTags or ctxt.ReleaseTags)
// a comma-separated list of any of these
//
func (ctxt *Context) match(name string, allTags map[string]bool) bool {
if name == "" {
if allTags != nil {
allTags[name] = true
}
return false
}
if i := strings.Index(name, ","); i >= 0 {
// comma-separated list
ok1 := ctxt.match(name[:i], allTags)
ok2 := ctxt.match(name[i+1:], allTags)
return ok1 && ok2
}
if strings.HasPrefix(name, "!!") { // bad syntax, reject always
return false
}
if strings.HasPrefix(name, "!") { // negation
return len(name) > 1 && !ctxt.match(name[1:], allTags)
}
// It records all consulted tags in allTags.
func (ctxt *Context) matchTag(name string, allTags map[string]bool) bool {
if allTags != nil {
allTags[name] = true
}
// Tags must be letters, digits, underscores or dots.
// Unlike in Go identifiers, all digits are fine (e.g., "386").
for _, c := range name {
if !unicode.IsLetter(c) && !unicode.IsDigit(c) && c != '_' && c != '.' {
return false
}
}
// special tags
if ctxt.CgoEnabled && name == "cgo" {
return true
@ -1946,10 +1939,10 @@ func (ctxt *Context) goodOSArchFile(name string, allTags map[string]bool) bool {
}
n := len(l)
if n >= 2 && knownOS[l[n-2]] && knownArch[l[n-1]] {
return ctxt.match(l[n-1], allTags) && ctxt.match(l[n-2], allTags)
return ctxt.matchTag(l[n-1], allTags) && ctxt.matchTag(l[n-2], allTags)
}
if n >= 1 && (knownOS[l[n-1]] || knownArch[l[n-1]]) {
return ctxt.match(l[n-1], allTags)
return ctxt.matchTag(l[n-1], allTags)
}
return true
}

92
src/go/build/build_test.go
View File

@ -30,7 +30,7 @@ func TestMatch(t *testing.T) {
match := func(tag string, want map[string]bool) {
t.Helper()
m := make(map[string]bool)
if !ctxt.match(tag, m) {
if !ctxt.matchAuto(tag, m) {
t.Errorf("%s context should match %s, does not", what, tag)
}
if !reflect.DeepEqual(m, want) {
@ -40,7 +40,7 @@ func TestMatch(t *testing.T) {
nomatch := func(tag string, want map[string]bool) {
t.Helper()
m := make(map[string]bool)
if ctxt.match(tag, m) {
if ctxt.matchAuto(tag, m) {
t.Errorf("%s context should NOT match %s, does", what, tag)
}
if !reflect.DeepEqual(m, want) {
@ -153,6 +153,13 @@ var shouldBuildTests = []struct {
tags: map[string]bool{"yes": true},
shouldBuild: true,
},
{
name: "Yes2",
content: "//go:build yes\n" +
"package main\n",
tags: map[string]bool{"yes": true},
shouldBuild: true,
},
{
name: "Or",
content: "// +build no yes\n\n" +
@ -160,6 +167,13 @@ var shouldBuildTests = []struct {
tags: map[string]bool{"yes": true, "no": true},
shouldBuild: true,
},
{
name: "Or2",
content: "//go:build no || yes\n" +
"package main\n",
tags: map[string]bool{"yes": true, "no": true},
shouldBuild: true,
},
{
name: "And",
content: "// +build no,yes\n\n" +
@ -167,6 +181,13 @@ var shouldBuildTests = []struct {
tags: map[string]bool{"yes": true, "no": true},
shouldBuild: false,
},
{
name: "And2",
content: "//go:build no && yes\n" +
"package main\n",
tags: map[string]bool{"yes": true, "no": true},
shouldBuild: false,
},
{
name: "Cgo",
content: "// +build cgo\n\n" +
@ -177,12 +198,23 @@ var shouldBuildTests = []struct {
tags: map[string]bool{"cgo": true},
shouldBuild: false,
},
{
name: "Cgo2",
content: "//go:build cgo\n" +
"// Copyright The Go Authors.\n\n" +
"// This package implements parsing of tags like\n" +
"// +build tag1\n" +
"package build",
tags: map[string]bool{"cgo": true},
shouldBuild: false,
},
{
name: "AfterPackage",
content: "// Copyright The Go Authors.\n\n" +
"package build\n\n" +
"// shouldBuild checks tags given by lines of the form\n" +
"// +build tag\n" +
"//go:build tag\n" +
"func shouldBuild(content []byte)\n",
tags: map[string]bool{},
shouldBuild: true,
@ -194,6 +226,13 @@ var shouldBuildTests = []struct {
tags: map[string]bool{},
shouldBuild: true,
},
{
name: "TooClose2",
content: "//go:build yes\n" +
"package main\n",
tags: map[string]bool{"yes": true},
shouldBuild: true,
},
{
name: "TooCloseNo",
content: "// +build no\n" +
@ -201,6 +240,13 @@ var shouldBuildTests = []struct {
tags: map[string]bool{},
shouldBuild: true,
},
{
name: "TooCloseNo2",
content: "//go:build no\n" +
"package main\n",
tags: map[string]bool{"no": true},
shouldBuild: false,
},
{
name: "BinaryOnly",
content: "//go:binary-only-package\n" +
@ -210,21 +256,22 @@ var shouldBuildTests = []struct {
binaryOnly: true,
shouldBuild: true,
},
{
name: "BinaryOnly2",
content: "//go:binary-only-package\n" +
"//go:build no\n" +
"package main\n",
tags: map[string]bool{"no": true},
binaryOnly: true,
shouldBuild: false,
},
{
name: "ValidGoBuild",
content: "// +build yes\n\n" +
"//go:build no\n" +
"package main\n",
tags: map[string]bool{"yes": true},
shouldBuild: true,
},
{
name: "MissingBuild",
content: "//go:build no\n" +
"package main\n",
tags: map[string]bool{},
tags: map[string]bool{"no": true},
shouldBuild: false,
err: errGoBuildWithoutBuild,
},
{
name: "MissingBuild2",
@ -232,20 +279,8 @@ var shouldBuildTests = []struct {
"// +build yes\n\n" +
"//go:build no\n" +
"package main\n",
tags: map[string]bool{},
tags: map[string]bool{"no": true},
shouldBuild: false,
err: errGoBuildWithoutBuild,
},
{
name: "MissingBuild2",
content: "/*\n" +
"// +build yes\n\n" +
"*/\n" +
"//go:build no\n" +
"package main\n",
tags: map[string]bool{},
shouldBuild: false,
err: errGoBuildWithoutBuild,
},
{
name: "Comment1",
@ -263,9 +298,8 @@ var shouldBuildTests = []struct {
"*/\n\n" +
"//go:build no\n" +
"package main\n",
tags: map[string]bool{},
tags: map[string]bool{"no": true},
shouldBuild: false,
err: errGoBuildWithoutBuild,
},
{
name: "Comment3",
@ -274,9 +308,8 @@ var shouldBuildTests = []struct {
"*/\n\n" +
"//go:build no\n" +
"package main\n",
tags: map[string]bool{},
tags: map[string]bool{"no": true},
shouldBuild: false,
err: errGoBuildWithoutBuild,
},
{
name: "Comment4",
@ -290,9 +323,8 @@ var shouldBuildTests = []struct {
content: "/**/\n" +
"//go:build no\n" +
"package main\n",
tags: map[string]bool{},
tags: map[string]bool{"no": true},
shouldBuild: false,
err: errGoBuildWithoutBuild,
},
}

2
src/go/build/deps_test.go
View File

@ -295,7 +295,7 @@ var depsRules = `
FMT
< go/build/constraint;
go/doc, go/parser, internal/goroot, internal/goversion
go/build/constraint, go/doc, go/parser, internal/goroot, internal/goversion
< go/build;
DEBUG, go/build, go/types, text/scanner