feat: option to strictly follow Go autogenerated file convention (#4507)

.golangci.next.reference.yml

@@ -2814,6 +2814,12 @@ issues:
   # Default: false
   exclude-case-sensitive: false
 
+  # To follow strict Go autogenerated file convention.
+  # https://go.dev/s/generatedcode
+  # By default a lax pattern is applied.
+  # Default: false
+  exclude-autogenerated-strict: true
+
   # The list of ids of default excludes to include or disable.
   # https://golangci-lint.run/usage/false-positives/#default-exclusions
   # Default: []

jsonschema/golangci.next.jsonschema.json

@@ -3342,6 +3342,11 @@
           "type": "boolean",
           "default": false
         },
+        "exclude-autogenerated-strict": {
+          "description": "To follow strict Go autogenerated file convention",
+          "type": "boolean",
+          "default": false
+        },
         "include": {
           "description": "The list of ids of default excludes to include or disable.",
           "type": "array",

pkg/config/issues.go

@@ -105,11 +105,12 @@ var DefaultExcludePatterns = []ExcludePattern{
 }
 
 type Issues struct {
-	IncludeDefaultExcludes []string      `mapstructure:"include"`
-	ExcludeCaseSensitive   bool          `mapstructure:"exclude-case-sensitive"`
-	ExcludePatterns        []string      `mapstructure:"exclude"`
-	ExcludeRules           []ExcludeRule `mapstructure:"exclude-rules"`
-	UseDefaultExcludes     bool          `mapstructure:"exclude-use-default"`
+	IncludeDefaultExcludes     []string      `mapstructure:"include"`
+	ExcludeCaseSensitive       bool          `mapstructure:"exclude-case-sensitive"`
+	ExcludePatterns            []string      `mapstructure:"exclude"`
+	ExcludeRules               []ExcludeRule `mapstructure:"exclude-rules"`
+	ExcludeAutogeneratedStrict bool          `mapstructure:"exclude-autogenerated-strict"`
+	UseDefaultExcludes         bool          `mapstructure:"exclude-use-default"`
 
 	MaxIssuesPerLinter int `mapstructure:"max-issues-per-linter"`
 	MaxSameIssues      int `mapstructure:"max-same-issues"`

pkg/lint/runner.go

@@ -72,7 +72,7 @@ func NewRunner(log logutils.Log, cfg *config.Config, goenv *goutil.Env,
 			skipFilesProcessor,
 			skipDirsProcessor, // must be after path prettifier
 
-			processors.NewAutogeneratedExclude(),
+			processors.NewAutogeneratedExclude(cfg.Issues.ExcludeAutogeneratedStrict),
 
 			// Must be before exclude because users see already marked output and configure excluding by it.
 			processors.NewIdentifierMarker(),

pkg/result/processors/autogenerated_exclude.go

@@ -6,32 +6,43 @@ import (
 	"go/parser"
 	"go/token"
 	"path/filepath"
+	"regexp"
 	"strings"
 
 	"github.com/golangci/golangci-lint/pkg/logutils"
 	"github.com/golangci/golangci-lint/pkg/result"
 )
 
-var autogenDebugf = logutils.Debug(logutils.DebugKeyAutogenExclude)
+const (
+	genCodeGenerated = "code generated"
+	genDoNotEdit     = "do not edit"
+	genAutoFile      = "autogenerated file" // easyjson
+)
 
-type ageFileSummary struct {
-	isGenerated bool
-}
+var _ Processor = &AutogeneratedExclude{}
 
-type ageFileSummaryCache map[string]*ageFileSummary
+type fileSummary struct {
+	generated bool
+}
 
 type AutogeneratedExclude struct {
-	fileSummaryCache ageFileSummaryCache
+	debugf logutils.DebugFunc
+
+	strict        bool
+	strictPattern *regexp.Regexp
+
+	fileSummaryCache map[string]*fileSummary
 }
 
-func NewAutogeneratedExclude() *AutogeneratedExclude {
+func NewAutogeneratedExclude(strict bool) *AutogeneratedExclude {
 	return &AutogeneratedExclude{
-		fileSummaryCache: ageFileSummaryCache{},
+		debugf:           logutils.Debug(logutils.DebugKeyAutogenExclude),
+		strict:           strict,
+		strictPattern:    regexp.MustCompile(`^// Code generated .* DO NOT EDIT\.$`),
+		fileSummaryCache: map[string]*fileSummary{},
 	}
 }
 
-var _ Processor = &AutogeneratedExclude{}
-
 func (p *AutogeneratedExclude) Name() string {
 	return "autogenerated_exclude"
 }
@@ -40,11 +51,7 @@ func (p *AutogeneratedExclude) Process(issues []result.Issue) ([]result.Issue, e
 	return filterIssuesErr(issues, p.shouldPassIssue)
 }
 
-func isSpecialAutogeneratedFile(filePath string) bool {
-	fileName := filepath.Base(filePath)
-	// fake files or generation definitions to which //line points to for generated files
-	return filepath.Ext(fileName) != ".go"
-}
+func (p *AutogeneratedExclude) Finish() {}
 
 func (p *AutogeneratedExclude) shouldPassIssue(issue *result.Issue) (bool, error) {
 	if issue.FromLinter == "typecheck" {
@@ -56,66 +63,96 @@ func (p *AutogeneratedExclude) shouldPassIssue(issue *result.Issue) (bool, error
 		return true, nil
 	}
 
-	if isSpecialAutogeneratedFile(issue.FilePath()) {
+	if !isGoFile(issue.FilePath()) {
 		return false, nil
 	}
 
-	fs, err := p.getOrCreateFileSummary(issue)
-	if err != nil {
-		return false, err
+	// The file is already known.
+	fs := p.fileSummaryCache[issue.FilePath()]
+	if fs != nil {
+		return !fs.generated, nil
 	}
 
+	fs = &fileSummary{}
+	p.fileSummaryCache[issue.FilePath()] = fs
+
+	if issue.FilePath() == "" {
+		return false, errors.New("no file path for issue")
+	}
+
+	if p.strict {
+		var err error
+		fs.generated, err = p.isGeneratedFileStrict(issue.FilePath())
+		if err != nil {
+			return false, fmt.Errorf("failed to get doc of file %s: %w", issue.FilePath(), err)
+		}
+	} else {
+		doc, err := getComments(issue.FilePath())
+		if err != nil {
+			return false, fmt.Errorf("failed to get doc of file %s: %w", issue.FilePath(), err)
+		}
+
+		fs.generated = p.isGeneratedFileLax(doc)
+	}
+
+	p.debugf("file %q is generated: %t", issue.FilePath(), fs.generated)
+
 	// don't report issues for autogenerated files
-	return !fs.isGenerated, nil
+	return !fs.generated, nil
 }
 
-// isGenerated reports whether the source file is generated code.
-// Using a bit laxer rules than https://go.dev/s/generatedcode to
-// match more generated code. See #48 and #72.
-func isGeneratedFileByComment(doc string) bool {
-	const (
-		genCodeGenerated = "code generated"
-		genDoNotEdit     = "do not edit"
-		genAutoFile      = "autogenerated file" // easyjson
-	)
-
+// isGeneratedFileLax reports whether the source file is generated code.
+// Using a bit laxer rules than https://go.dev/s/generatedcode to match more generated code.
+// See https://github.com/golangci/golangci-lint/issues/48 and https://github.com/golangci/golangci-lint/issues/72.
+func (p *AutogeneratedExclude) isGeneratedFileLax(doc string) bool {
 	markers := []string{genCodeGenerated, genDoNotEdit, genAutoFile}
+
 	doc = strings.ToLower(doc)
+
 	for _, marker := range markers {
 		if strings.Contains(doc, marker) {
-			autogenDebugf("doc contains marker %q: file is generated", marker)
+			p.debugf("doc contains marker %q: file is generated", marker)
+
 			return true
 		}
 	}
 
-	autogenDebugf("doc of len %d doesn't contain any of markers: %s", len(doc), markers)
+	p.debugf("doc of len %d doesn't contain any of markers: %s", len(doc), markers)
+
 	return false
 }
 
-func (p *AutogeneratedExclude) getOrCreateFileSummary(issue *result.Issue) (*ageFileSummary, error) {
-	fs := p.fileSummaryCache[issue.FilePath()]
-	if fs != nil {
-		return fs, nil
+// Based on https://go.dev/s/generatedcode
+// > This line must appear before the first non-comment, non-blank text in the file.
+func (p *AutogeneratedExclude) isGeneratedFileStrict(filePath string) (bool, error) {
+	file, err := parser.ParseFile(token.NewFileSet(), filePath, nil, parser.PackageClauseOnly|parser.ParseComments)
+	if err != nil {
+		return false, fmt.Errorf("failed to parse file: %w", err)
 	}
 
-	fs = &ageFileSummary{}
-	p.fileSummaryCache[issue.FilePath()] = fs
-
-	if issue.FilePath() == "" {
-		return nil, errors.New("no file path for issue")
+	if file == nil || len(file.Comments) == 0 {
+		return false, nil
 	}
 
-	doc, err := getDoc(issue.FilePath())
-	if err != nil {
-		return nil, fmt.Errorf("failed to get doc of file %s: %w", issue.FilePath(), err)
+	for _, comment := range file.Comments {
+		if comment.Pos() > file.Package {
+			return false, nil
+		}
+
+		for _, line := range comment.List {
+			generated := p.strictPattern.MatchString(line.Text)
+			if generated {
+				p.debugf("doc contains ignore expression: file is generated")
+
+				return true, nil
+			}
+		}
 	}
 
-	fs.isGenerated = isGeneratedFileByComment(doc)
-	autogenDebugf("file %q is generated: %t", issue.FilePath(), fs.isGenerated)
-	return fs, nil
+	return false, nil
 }
 
-func getDoc(filePath string) (string, error) {
+func getComments(filePath string) (string, error) {
 	fset := token.NewFileSet()
 	syntax, err := parser.ParseFile(fset, filePath, nil, parser.PackageClauseOnly|parser.ParseComments)
 	if err != nil {
@@ -130,4 +167,6 @@ func getDoc(filePath string) (string, error) {
 	return strings.Join(docLines, "\n"), nil
 }
 
-func (p *AutogeneratedExclude) Finish() {}
+func isGoFile(name string) bool {
+	return filepath.Ext(name) == ".go"
+}