1 files changed, 174 insertions, 0 deletions
diff --git a/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/buildtag/buildtag_old.go b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/buildtag/buildtag_old.go
new file mode 100644
index 0000000000..e9234925f9
--- /dev/null
+++ b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/buildtag/buildtag_old.go
@@ -0,0 +1,174 @@
+// 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.
+
+// TODO(rsc): Delete this file once Go 1.17 comes out and we can retire Go 1.15 support.
+
+//go:build !go1.16
+// +build !go1.16
+
+// 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("//")
+)