--- /dev/null
+// 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 buildtag defines an Analyzer that checks build tags.
+package buildtag
+
+import (
+ "bytes"
+ "fmt"
+ "go/ast"
+ "go/parser"
+ "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) {
+ pastCutoff := false
+ for _, group := range f.Comments {
+ // A +build comment is ignored after or adjoining the package declaration.
+ if group.End()+1 >= f.Package {
+ pastCutoff = true
+ }
+
+ // "+build" is ignored within or after a /*...*/ comment.
+ if !strings.HasPrefix(group.List[0].Text, "//") {
+ pastCutoff = true
+ continue
+ }
+
+ // Check each line of a //-comment.
+ for _, c := range group.List {
+ if !strings.Contains(c.Text, "+build") {
+ continue
+ }
+ if err := checkLine(c.Text, pastCutoff); err != nil {
+ pass.Reportf(c.Pos(), "%s", err)
+ }
+ }
+ }
+}
+
+func checkOtherFile(pass *analysis.Pass, filename string) error {
+ content, tf, err := analysisutil.ReadFile(pass.Fset, filename)
+ if err != nil {
+ return err
+ }
+
+ // We must look at the raw lines, as build tags may appear in non-Go
+ // files such as assembly files.
+ lines := bytes.SplitAfter(content, nl)
+
+ // Determine cutpoint where +build comments are no longer valid.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 cutoff int
+ for i, line := range lines {
+ line = bytes.TrimSpace(line)
+ if !bytes.HasPrefix(line, slashSlash) {
+ if len(line) > 0 {
+ break
+ }
+ cutoff = i
+ }
+ }
+
+ for i, line := range lines {
+ line = bytes.TrimSpace(line)
+ if !bytes.HasPrefix(line, slashSlash) {
+ continue
+ }
+ if !bytes.Contains(line, []byte("+build")) {
+ continue
+ }
+ if err := checkLine(string(line), i >= cutoff); err != nil {
+ pass.Reportf(analysisutil.LineStart(tf, i+1), "%s", err)
+ continue
+ }
+ }
+ return nil
+}
+
+// checkLine checks a line that starts with "//" and contains "+build".
+func checkLine(line string, pastCutoff bool) error {
+ line = strings.TrimPrefix(line, "//")
+ line = strings.TrimSpace(line)
+
+ if strings.HasPrefix(line, "+build") {
+ fields := strings.Fields(line)
+ if fields[0] != "+build" {
+ // Comment is something like +buildasdf not +build.
+ return fmt.Errorf("possible malformed +build comment")
+ }
+ if pastCutoff {
+ return fmt.Errorf("+build comment must appear before package clause and be followed by a blank line")
+ }
+ if err := checkArguments(fields); err != nil {
+ return err
+ }
+ } else {
+ // Comment with +build but not at beginning.
+ if !pastCutoff {
+ return fmt.Errorf("possible malformed +build comment")
+ }
+ }
+ return nil
+}
+
+func checkArguments(fields []string) error {
+ for _, arg := range fields[1:] {
+ for _, elem := range strings.Split(arg, ",") {
+ if strings.HasPrefix(elem, "!!") {
+ return fmt.Errorf("invalid double negative in build constraint: %s", arg)
+ }
+ elem = strings.TrimPrefix(elem, "!")
+ for _, c := range elem {
+ if !unicode.IsLetter(c) && !unicode.IsDigit(c) && c != '_' && c != '.' {
+ return fmt.Errorf("invalid non-alphanumeric build constraint: %s", arg)
+ }
+ }
+ }
+ }
+ return nil
+}
+
+var (
+ nl = []byte("\n")
+ slashSlash = []byte("//")
+)
projects / dotfiles / .git / blobdiff