libgo/go/golang.org/x/tools/go/analysis/passes/buildtag/buildtag.go - gofrontend - Git at Google

 // 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.

 //go:build go1.16
 // +build go1.16

 // Package buildtag defines an Analyzer that checks build tags.
 package buildtag

 import (
 	"go/ast"
 	"go/build/constraint"
 	"go/parser"
 	"go/token"
 	"strings"
 	"unicode"

 	"golang.org/x/tools/go/analysis"
 	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
 )

 const Doc = "check that +build tags are well-formed and correctly located"

 var Analyzer = &analysis.Analyzer{
 	Name: "buildtag",
 	Doc:  Doc,
 	Run:  runBuildTag,
 }

 func runBuildTag(pass *analysis.Pass) (interface{}, error) {
 	for _, f := range pass.Files {
 		checkGoFile(pass, f)
 	}
 	for _, name := range pass.OtherFiles {
 		if err := checkOtherFile(pass, name); err != nil {
 			return nil, err
 		}
 	}
 	for _, name := range pass.IgnoredFiles {
 		if strings.HasSuffix(name, ".go") {
 			f, err := parser.ParseFile(pass.Fset, name, nil, parser.ParseComments)
 			if err != nil {
 				// Not valid Go source code - not our job to diagnose, so ignore.
 				return nil, nil
 			}
 			checkGoFile(pass, f)
 		} else {
 			if err := checkOtherFile(pass, name); err != nil {
 				return nil, err
 			}
 		}
 	}
 	return nil, nil
 }

 func checkGoFile(pass *analysis.Pass, f *ast.File) {
 	var check checker
 	check.init(pass)
 	defer check.finish()

 	for _, group := range f.Comments {
 		// A +build comment is ignored after or adjoining the package declaration.
 		if group.End()+1 >= f.Package {
 			check.plusBuildOK = false
 		}
 		// A //go:build comment is ignored after the package declaration
 		// (but adjoining it is OK, in contrast to +build comments).
 		if group.Pos() >= f.Package {
 			check.goBuildOK = false
 		}

 		// Check each line of a //-comment.
 		for _, c := range group.List {
 			// "+build" is ignored within or after a /*...*/ comment.
 			if !strings.HasPrefix(c.Text, "//") {
 				check.plusBuildOK = false
 			}
 			check.comment(c.Slash, c.Text)
 		}
 	}
 }

 func checkOtherFile(pass *analysis.Pass, filename string) error {
 	var check checker
 	check.init(pass)
 	defer check.finish()

 	// We cannot use the Go parser, since this may not be a Go source file.
 	// Read the raw bytes instead.
 	content, tf, err := analysisutil.ReadFile(pass.Fset, filename)
 	if err != nil {
 		return err
 	}

 	check.file(token.Pos(tf.Base()), string(content))
 	return nil
 }

 type checker struct {
 	pass         *analysis.Pass
 	plusBuildOK  bool            // "+build" lines still OK
 	goBuildOK    bool            // "go:build" lines still OK
 	crossCheck   bool            // cross-check go:build and +build lines when done reading file
 	inStar       bool            // currently in a /* */ comment
 	goBuildPos   token.Pos       // position of first go:build line found
 	plusBuildPos token.Pos       // position of first "+build" line found
 	goBuild      constraint.Expr // go:build constraint found
 	plusBuild    constraint.Expr // AND of +build constraints found
 }

 func (check *checker) init(pass *analysis.Pass) {
 	check.pass = pass
 	check.goBuildOK = true
 	check.plusBuildOK = true
 	check.crossCheck = true
 }

 func (check *checker) file(pos token.Pos, text string) {
 	// Determine cutpoint where +build comments are no longer valid.
 	// They are valid in leading // comments in the file followed by
 	// a blank line.
 	//
 	// This must be done as a separate pass because of the
 	// requirement that the comment be followed by a blank line.
 	var plusBuildCutoff int
 	fullText := text
 	for text != "" {
 		i := strings.Index(text, "\n")
 		if i < 0 {
 			i = len(text)
 		} else {
 			i++
 		}
 		offset := len(fullText) - len(text)
 		line := text[:i]
 		text = text[i:]
 		line = strings.TrimSpace(line)
 		if !strings.HasPrefix(line, "//") && line != "" {
 			break
 		}
 		if line == "" {
 			plusBuildCutoff = offset
 		}
 	}

 	// Process each line.
 	// Must stop once we hit goBuildOK == false
 	text = fullText
 	check.inStar = false
 	for text != "" {
 		i := strings.Index(text, "\n")
 		if i < 0 {
 			i = len(text)
 		} else {
 			i++
 		}
 		offset := len(fullText) - len(text)
 		line := text[:i]
 		text = text[i:]
 		check.plusBuildOK = offset < plusBuildCutoff

 		if strings.HasPrefix(line, "//") {
 			check.comment(pos+token.Pos(offset), line)
 			continue
 		}

 		// Keep looking for the point at which //go:build comments
 		// stop being allowed. Skip over, cut out any /* */ comments.
 		for {
 			line = strings.TrimSpace(line)
 			if check.inStar {
 				i := strings.Index(line, "*/")
 				if i < 0 {
 					line = ""
 					break
 				}
 				line = line[i+len("*/"):]
 				check.inStar = false
 				continue
 			}
 			if strings.HasPrefix(line, "/*") {
 				check.inStar = true
 				line = line[len("/*"):]
 				continue
 			}
 			break
 		}
 		if line != "" {
 			// Found non-comment non-blank line.
 			// Ends space for valid //go:build comments,
 			// but also ends the fraction of the file we can
 			// reliably parse. From this point on we might
 			// incorrectly flag "comments" inside multiline
 			// string constants or anything else (this might
 			// not even be a Go program). So stop.
 			break
 		}
 	}
 }

 func (check *checker) comment(pos token.Pos, text string) {
 	if strings.HasPrefix(text, "//") {
 		if strings.Contains(text, "+build") {
 			check.plusBuildLine(pos, text)
 		}
 		if strings.Contains(text, "//go:build") {
 			check.goBuildLine(pos, text)
 		}
 	}
 	if strings.HasPrefix(text, "/*") {
 		if i := strings.Index(text, "\n"); i >= 0 {
 			// multiline /* */ comment - process interior lines
 			check.inStar = true
 			i++
 			pos += token.Pos(i)
 			text = text[i:]
 			for text != "" {
 				i := strings.Index(text, "\n")
 				if i < 0 {
 					i = len(text)
 				} else {
 					i++
 				}
 				line := text[:i]
 				if strings.HasPrefix(line, "//") {
 					check.comment(pos, line)
 				}
 				pos += token.Pos(i)
 				text = text[i:]
 			}
 			check.inStar = false
 		}
 	}
 }

 func (check *checker) goBuildLine(pos token.Pos, line string) {
 	if !constraint.IsGoBuild(line) {
 		if !strings.HasPrefix(line, "//go:build") && constraint.IsGoBuild("//"+strings.TrimSpace(line[len("//"):])) {
 			check.pass.Reportf(pos, "malformed //go:build line (space between // and go:build)")
 		}
 		return
 	}
 	if !check.goBuildOK || check.inStar {
 		check.pass.Reportf(pos, "misplaced //go:build comment")
 		check.crossCheck = false
 		return
 	}

 	if check.goBuildPos == token.NoPos {
 		check.goBuildPos = pos
 	} else {
 		check.pass.Reportf(pos, "unexpected extra //go:build line")
 		check.crossCheck = false
 	}

 	// testing hack: stop at // ERROR
 	if i := strings.Index(line, " // ERROR "); i >= 0 {
 		line = line[:i]
 	}

 	x, err := constraint.Parse(line)
 	if err != nil {
 		check.pass.Reportf(pos, "%v", err)
 		check.crossCheck = false
 		return
 	}

 	if check.goBuild == nil {
 		check.goBuild = x
 	}
 }

 func (check *checker) plusBuildLine(pos token.Pos, line string) {
 	line = strings.TrimSpace(line)
 	if !constraint.IsPlusBuild(line) {
 		// Comment with +build but not at beginning.
 		// Only report early in file.
 		if check.plusBuildOK && !strings.HasPrefix(line, "// want") {
 			check.pass.Reportf(pos, "possible malformed +build comment")
 		}
 		return
 	}
 	if !check.plusBuildOK { // inStar implies !plusBuildOK
 		check.pass.Reportf(pos, "misplaced +build comment")
 		check.crossCheck = false
 	}

 	if check.plusBuildPos == token.NoPos {
 		check.plusBuildPos = pos
 	}

 	// testing hack: stop at // ERROR
 	if i := strings.Index(line, " // ERROR "); i >= 0 {
 		line = line[:i]
 	}

 	fields := strings.Fields(line[len("//"):])
 	// IsPlusBuildConstraint check above implies fields[0] == "+build"
 	for _, arg := range fields[1:] {
 		for _, elem := range strings.Split(arg, ",") {
 			if strings.HasPrefix(elem, "!!") {
 				check.pass.Reportf(pos, "invalid double negative in build constraint: %s", arg)
 				check.crossCheck = false
 				continue
 			}
 			elem = strings.TrimPrefix(elem, "!")
 			for _, c := range elem {
 				if !unicode.IsLetter(c) && !unicode.IsDigit(c) && c != '_' && c != '.' {
 					check.pass.Reportf(pos, "invalid non-alphanumeric build constraint: %s", arg)
 					check.crossCheck = false
 					break
 				}
 			}
 		}
 	}

 	if check.crossCheck {
 		y, err := constraint.Parse(line)
 		if err != nil {
 			// Should never happen - constraint.Parse never rejects a // +build line.
 			// Also, we just checked the syntax above.
 			// Even so, report.
 			check.pass.Reportf(pos, "%v", err)
 			check.crossCheck = false
 			return
 		}
 		if check.plusBuild == nil {
 			check.plusBuild = y
 		} else {
 			check.plusBuild = &constraint.AndExpr{X: check.plusBuild, Y: y}
 		}
 	}
 }

 func (check *checker) finish() {
 	if !check.crossCheck || check.plusBuildPos == token.NoPos || check.goBuildPos == token.NoPos {
 		return
 	}

 	// Have both //go:build and // +build,
 	// with no errors found (crossCheck still true).
 	// Check they match.
 	var want constraint.Expr
 	lines, err := constraint.PlusBuildLines(check.goBuild)
 	if err != nil {
 		check.pass.Reportf(check.goBuildPos, "%v", err)
 		return
 	}
 	for _, line := range lines {
 		y, err := constraint.Parse(line)
 		if err != nil {
 			// Definitely should not happen, but not the user's fault.
 			// Do not report.
 			return
 		}
 		if want == nil {
 			want = y
 		} else {
 			want = &constraint.AndExpr{X: want, Y: y}
 		}
 	}
 	if want.String() != check.plusBuild.String() {
 		check.pass.Reportf(check.plusBuildPos, "+build lines do not match //go:build condition")
 		return
 	}
 }
	// 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.

	//go:build go1.16
	// +build go1.16

	// Package buildtag defines an Analyzer that checks build tags.
	package buildtag

	import (
	"go/ast"
	"go/build/constraint"
	"go/parser"
	"go/token"
	"strings"
	"unicode"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
	)

	const Doc = "check that +build tags are well-formed and correctly located"

	var Analyzer = &analysis.Analyzer{
	Name: "buildtag",
	Doc: Doc,
	Run: runBuildTag,
	}

	func runBuildTag(pass *analysis.Pass) (interface{}, error) {
	for _, f := range pass.Files {
	checkGoFile(pass, f)
	}
	for _, name := range pass.OtherFiles {
	if err := checkOtherFile(pass, name); err != nil {
	return nil, err
	}
	}
	for _, name := range pass.IgnoredFiles {
	if strings.HasSuffix(name, ".go") {
	f, err := parser.ParseFile(pass.Fset, name, nil, parser.ParseComments)
	if err != nil {
	// Not valid Go source code - not our job to diagnose, so ignore.
	return nil, nil
	}
	checkGoFile(pass, f)
	} else {
	if err := checkOtherFile(pass, name); err != nil {
	return nil, err
	}
	}
	}
	return nil, nil
	}

	func checkGoFile(pass analysis.Pass, f ast.File) {
	var check checker
	check.init(pass)
	defer check.finish()

	for _, group := range f.Comments {
	// A +build comment is ignored after or adjoining the package declaration.
	if group.End()+1 >= f.Package {
	check.plusBuildOK = false
	}
	// A //go:build comment is ignored after the package declaration
	// (but adjoining it is OK, in contrast to +build comments).
	if group.Pos() >= f.Package {
	check.goBuildOK = false
	}

	// Check each line of a //-comment.
	for _, c := range group.List {
	// "+build" is ignored within or after a /.../ comment.
	if !strings.HasPrefix(c.Text, "//") {
	check.plusBuildOK = false
	}
	check.comment(c.Slash, c.Text)
	}
	}
	}

	func checkOtherFile(pass *analysis.Pass, filename string) error {
	var check checker
	check.init(pass)
	defer check.finish()

	// We cannot use the Go parser, since this may not be a Go source file.
	// Read the raw bytes instead.
	content, tf, err := analysisutil.ReadFile(pass.Fset, filename)
	if err != nil {
	return err
	}

	check.file(token.Pos(tf.Base()), string(content))
	return nil
	}

	type checker struct {
	pass *analysis.Pass
	plusBuildOK bool // "+build" lines still OK
	goBuildOK bool // "go:build" lines still OK
	crossCheck bool // cross-check go:build and +build lines when done reading file
	inStar bool // currently in a /* */ comment
	goBuildPos token.Pos // position of first go:build line found
	plusBuildPos token.Pos // position of first "+build" line found
	goBuild constraint.Expr // go:build constraint found
	plusBuild constraint.Expr // AND of +build constraints found
	}

	func (check checker) init(pass analysis.Pass) {
	check.pass = pass
	check.goBuildOK = true
	check.plusBuildOK = true
	check.crossCheck = true
	}

	func (check *checker) file(pos token.Pos, text string) {
	// Determine cutpoint where +build comments are no longer valid.
	// They are valid in leading // comments in the file followed by
	// a blank line.
	//
	// This must be done as a separate pass because of the
	// requirement that the comment be followed by a blank line.
	var plusBuildCutoff int
	fullText := text
	for text != "" {
	i := strings.Index(text, "\n")
	if i < 0 {
	i = len(text)
	} else {
	i++
	}
	offset := len(fullText) - len(text)
	line := text[:i]
	text = text[i:]
	line = strings.TrimSpace(line)
	if !strings.HasPrefix(line, "//") && line != "" {
	break
	}
	if line == "" {
	plusBuildCutoff = offset
	}
	}

	// Process each line.
	// Must stop once we hit goBuildOK == false
	text = fullText
	check.inStar = false
	for text != "" {
	i := strings.Index(text, "\n")
	if i < 0 {
	i = len(text)
	} else {
	i++
	}
	offset := len(fullText) - len(text)
	line := text[:i]
	text = text[i:]
	check.plusBuildOK = offset < plusBuildCutoff

	if strings.HasPrefix(line, "//") {
	check.comment(pos+token.Pos(offset), line)
	continue
	}

	// Keep looking for the point at which //go:build comments
	// stop being allowed. Skip over, cut out any /* */ comments.
	for {
	line = strings.TrimSpace(line)
	if check.inStar {
	i := strings.Index(line, "*/")
	if i < 0 {
	line = ""
	break
	}
	line = line[i+len("*/"):]
	check.inStar = false
	continue
	}
	if strings.HasPrefix(line, "/*") {
	check.inStar = true
	line = line[len("/*"):]
	continue
	}
	break
	}
	if line != "" {
	// Found non-comment non-blank line.
	// Ends space for valid //go:build comments,
	// but also ends the fraction of the file we can
	// reliably parse. From this point on we might
	// incorrectly flag "comments" inside multiline
	// string constants or anything else (this might
	// not even be a Go program). So stop.
	break
	}
	}
	}

	func (check *checker) comment(pos token.Pos, text string) {
	if strings.HasPrefix(text, "//") {
	if strings.Contains(text, "+build") {
	check.plusBuildLine(pos, text)
	}
	if strings.Contains(text, "//go:build") {
	check.goBuildLine(pos, text)
	}
	}
	if strings.HasPrefix(text, "/*") {
	if i := strings.Index(text, "\n"); i >= 0 {
	// multiline /* */ comment - process interior lines
	check.inStar = true
	i++
	pos += token.Pos(i)
	text = text[i:]
	for text != "" {
	i := strings.Index(text, "\n")
	if i < 0 {
	i = len(text)
	} else {
	i++
	}
	line := text[:i]
	if strings.HasPrefix(line, "//") {
	check.comment(pos, line)
	}
	pos += token.Pos(i)
	text = text[i:]
	}
	check.inStar = false
	}
	}
	}

	func (check *checker) goBuildLine(pos token.Pos, line string) {
	if !constraint.IsGoBuild(line) {
	if !strings.HasPrefix(line, "//go:build") && constraint.IsGoBuild("//"+strings.TrimSpace(line[len("//"):])) {
	check.pass.Reportf(pos, "malformed //go:build line (space between // and go:build)")
	}
	return
	}
	if !check.goBuildOK \|\| check.inStar {
	check.pass.Reportf(pos, "misplaced //go:build comment")
	check.crossCheck = false
	return
	}

	if check.goBuildPos == token.NoPos {
	check.goBuildPos = pos
	} else {
	check.pass.Reportf(pos, "unexpected extra //go:build line")
	check.crossCheck = false
	}

	// testing hack: stop at // ERROR
	if i := strings.Index(line, " // ERROR "); i >= 0 {
	line = line[:i]
	}

	x, err := constraint.Parse(line)
	if err != nil {
	check.pass.Reportf(pos, "%v", err)
	check.crossCheck = false
	return
	}

	if check.goBuild == nil {
	check.goBuild = x
	}
	}

	func (check *checker) plusBuildLine(pos token.Pos, line string) {
	line = strings.TrimSpace(line)
	if !constraint.IsPlusBuild(line) {
	// Comment with +build but not at beginning.
	// Only report early in file.
	if check.plusBuildOK && !strings.HasPrefix(line, "// want") {
	check.pass.Reportf(pos, "possible malformed +build comment")
	}
	return
	}
	if !check.plusBuildOK { // inStar implies !plusBuildOK
	check.pass.Reportf(pos, "misplaced +build comment")
	check.crossCheck = false
	}

	if check.plusBuildPos == token.NoPos {
	check.plusBuildPos = pos
	}

	// testing hack: stop at // ERROR
	if i := strings.Index(line, " // ERROR "); i >= 0 {
	line = line[:i]
	}

	fields := strings.Fields(line[len("//"):])
	// IsPlusBuildConstraint check above implies fields[0] == "+build"
	for _, arg := range fields[1:] {
	for _, elem := range strings.Split(arg, ",") {
	if strings.HasPrefix(elem, "!!") {
	check.pass.Reportf(pos, "invalid double negative in build constraint: %s", arg)
	check.crossCheck = false
	continue
	}
	elem = strings.TrimPrefix(elem, "!")
	for _, c := range elem {
	if !unicode.IsLetter(c) && !unicode.IsDigit(c) && c != '_' && c != '.' {
	check.pass.Reportf(pos, "invalid non-alphanumeric build constraint: %s", arg)
	check.crossCheck = false
	break
	}
	}
	}
	}

	if check.crossCheck {
	y, err := constraint.Parse(line)
	if err != nil {
	// Should never happen - constraint.Parse never rejects a // +build line.
	// Also, we just checked the syntax above.
	// Even so, report.
	check.pass.Reportf(pos, "%v", err)
	check.crossCheck = false
	return
	}
	if check.plusBuild == nil {
	check.plusBuild = y
	} else {
	check.plusBuild = &constraint.AndExpr{X: check.plusBuild, Y: y}
	}
	}
	}

	func (check *checker) finish() {
	if !check.crossCheck \|\| check.plusBuildPos == token.NoPos \|\| check.goBuildPos == token.NoPos {
	return
	}

	// Have both //go:build and // +build,
	// with no errors found (crossCheck still true).
	// Check they match.
	var want constraint.Expr
	lines, err := constraint.PlusBuildLines(check.goBuild)
	if err != nil {
	check.pass.Reportf(check.goBuildPos, "%v", err)
	return
	}
	for _, line := range lines {
	y, err := constraint.Parse(line)
	if err != nil {
	// Definitely should not happen, but not the user's fault.
	// Do not report.
	return
	}
	if want == nil {
	want = y
	} else {
	want = &constraint.AndExpr{X: want, Y: y}
	}
	}
	if want.String() != check.plusBuild.String() {
	check.pass.Reportf(check.plusBuildPos, "+build lines do not match //go:build condition")
	return
	}
	}