unused: support passing in options (#4086)

Co-authored-by: Fernandez Ludovic <ldez@users.noreply.github.com>

.golangci.reference.yml

@@ -2016,6 +2016,29 @@ linters-settings:
     # Default: false
     check-exported: true
 
+  unused:
+    # Mark all struct fields that have been written to as used.
+    # Default: true
+    field-writes-are-uses: false
+    # Treat IncDec statement (e.g. `i++` or `i--`) as both read and write operation instead of just write.
+    # Default: false
+    post-statements-are-reads: true
+    # Mark all exported identifiers as used.
+    # Default: true
+    exported-is-used: false
+    # Mark all exported fields as used.
+    # default: true
+    exported-fields-are-used: false
+    # Mark all function parameters as used.
+    # default: true
+    parameters-are-used: false
+    # Mark all local variables as used.
+    # default: true
+    local-variables-are-used: false
+    # Mark all identifiers inside generated files as used.
+    # Default: true
+    generated-is-used: false
+
   varcheck:
     # Check usage of exported fields and variables.
     # Default: false

pkg/config/linters_settings.go

@@ -126,6 +126,15 @@ var defaultLintersSettings = LintersSettings{
 	Unparam: UnparamSettings{
 		Algo: "cha",
 	},
+	Unused: UnusedSettings{
+		FieldWritesAreUses:     true,
+		PostStatementsAreReads: false,
+		ExportedIsUsed:         true,
+		ExportedFieldsAreUsed:  true,
+		ParametersAreUsed:      true,
+		LocalVariablesAreUsed:  true,
+		GeneratedIsUsed:        true,
+	},
 	UseStdlibVars: UseStdlibVarsSettings{
 		HTTPMethod:     true,
 		HTTPStatusCode: true,
@@ -223,6 +232,7 @@ type LintersSettings struct {
 	Testpackage      TestpackageSettings
 	Thelper          ThelperSettings
 	Unparam          UnparamSettings
+	Unused           UnusedSettings
 	UseStdlibVars    UseStdlibVarsSettings
 	Varcheck         VarCheckSettings
 	Varnamelen       VarnamelenSettings
@@ -794,6 +804,16 @@ type UnparamSettings struct {
 	Algo          string
 }
 
+type UnusedSettings struct {
+	FieldWritesAreUses     bool `mapstructure:"field-writes-are-uses"`
+	PostStatementsAreReads bool `mapstructure:"post-statements-are-reads"`
+	ExportedIsUsed         bool `mapstructure:"exported-is-used"`
+	ExportedFieldsAreUsed  bool `mapstructure:"exported-fields-are-used"`
+	ParametersAreUsed      bool `mapstructure:"parameters-are-used"`
+	LocalVariablesAreUsed  bool `mapstructure:"local-variables-are-used"`
+	GeneratedIsUsed        bool `mapstructure:"generated-is-used"`
+}
+
 type VarCheckSettings struct {
 	CheckExportedFields bool `mapstructure:"exported-fields"`
 }

pkg/golinters/unused.go

@@ -5,6 +5,9 @@ import (
 	"sync"
 
 	"golang.org/x/tools/go/analysis"
+	"honnef.co/go/tools/analysis/facts/directives"
+	"honnef.co/go/tools/analysis/facts/generated"
+	"honnef.co/go/tools/analysis/lint"
 	"honnef.co/go/tools/unused"
 
 	"github.com/golangci/golangci-lint/pkg/config"
@@ -15,11 +18,7 @@ import (
 
 const unusedName = "unused"
 
-type UnusedSettings struct {
+func NewUnused(settings *config.UnusedSettings, scSettings *config.StaticCheckSettings) *goanalysis.Linter {
-	GoVersion string
-}
-
-func NewUnused(settings *config.StaticCheckSettings) *goanalysis.Linter {
 	var mu sync.Mutex
 	var resIssues []goanalysis.Issue
 
@@ -28,11 +27,7 @@ func NewUnused(settings *config.StaticCheckSettings) *goanalysis.Linter {
 		Doc:      unused.Analyzer.Analyzer.Doc,
 		Requires: unused.Analyzer.Analyzer.Requires,
 		Run: func(pass *analysis.Pass) (any, error) {
-			issues, err := runUnused(pass)
+			issues := runUnused(pass, settings)
-			if err != nil {
-				return nil, err
-			}
-
 			if len(issues) == 0 {
 				return nil, nil
 			}
@@ -45,7 +40,7 @@ func NewUnused(settings *config.StaticCheckSettings) *goanalysis.Linter {
 		},
 	}
 
-	setAnalyzerGoVersion(analyzer, getGoVersion(settings))
+	setAnalyzerGoVersion(analyzer, getGoVersion(scSettings))
 
 	return goanalysis.NewLinter(
 		unusedName,
@@ -57,21 +52,18 @@ func NewUnused(settings *config.StaticCheckSettings) *goanalysis.Linter {
 	}).WithLoadMode(goanalysis.LoadModeTypesInfo)
 }
 
-func runUnused(pass *analysis.Pass) ([]goanalysis.Issue, error) {
+func runUnused(pass *analysis.Pass, cfg *config.UnusedSettings) []goanalysis.Issue {
-	res, err := unused.Analyzer.Analyzer.Run(pass)
+	res := getUnusedResults(pass, cfg)
-	if err != nil {
-		return nil, err
-	}
 
 	used := make(map[string]bool)
-	for _, obj := range res.(unused.Result).Used {
+	for _, obj := range res.Used {
 		used[fmt.Sprintf("%s %d %s", obj.Position.Filename, obj.Position.Line, obj.Name)] = true
 	}
 
 	var issues []goanalysis.Issue
 
 	// Inspired by https://github.com/dominikh/go-tools/blob/d694aadcb1f50c2d8ac0a1dd06217ebb9f654764/lintcmd/lint.go#L177-L197
-	for _, object := range res.(unused.Result).Unused {
+	for _, object := range res.Unused {
 		if object.Kind == "type param" {
 			continue
 		}
@@ -90,5 +82,31 @@ func runUnused(pass *analysis.Pass) ([]goanalysis.Issue, error) {
 		issues = append(issues, issue)
 	}
 
-	return issues, nil
+	return issues
+}
+
+func getUnusedResults(pass *analysis.Pass, settings *config.UnusedSettings) unused.Result {
+	opts := unused.Options{
+		FieldWritesAreUses:     settings.FieldWritesAreUses,
+		PostStatementsAreReads: settings.PostStatementsAreReads,
+		ExportedIsUsed:         settings.ExportedIsUsed,
+		ExportedFieldsAreUsed:  settings.ExportedFieldsAreUsed,
+		ParametersAreUsed:      settings.ParametersAreUsed,
+		LocalVariablesAreUsed:  settings.LocalVariablesAreUsed,
+		GeneratedIsUsed:        settings.GeneratedIsUsed,
+	}
+
+	// ref: https://github.com/dominikh/go-tools/blob/4ec1f474ca6c0feb8e10a8fcca4ab95f5b5b9881/internal/cmd/unused/unused.go#L68
+	nodes := unused.Graph(pass.Fset,
+		pass.Files,
+		pass.Pkg,
+		pass.TypesInfo,
+		pass.ResultOf[directives.Analyzer].([]lint.Directive),
+		pass.ResultOf[generated.Analyzer].(map[string]generated.Generator),
+		opts,
+	)
+
+	sg := unused.SerializedGraph{}
+	sg.Merge(nodes)
+	return sg.Results()
 }

pkg/lint/lintersdb/manager.go

@@ -137,7 +137,7 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 		testpackageCfg      *config.TestpackageSettings
 		thelperCfg          *config.ThelperSettings
 		unparamCfg          *config.UnparamSettings
-		unusedCfg           *config.StaticCheckSettings
+		unusedCfg           *config.UnusedSettings
 		usestdlibvars       *config.UseStdlibVarsSettings
 		varcheckCfg         *config.VarCheckSettings
 		varnamelenCfg       *config.VarnamelenSettings
@@ -218,7 +218,7 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 		testpackageCfg = &m.cfg.LintersSettings.Testpackage
 		thelperCfg = &m.cfg.LintersSettings.Thelper
 		unparamCfg = &m.cfg.LintersSettings.Unparam
-		unusedCfg = new(config.StaticCheckSettings)
+		unusedCfg = &m.cfg.LintersSettings.Unused
 		usestdlibvars = &m.cfg.LintersSettings.UseStdlibVars
 		varcheckCfg = &m.cfg.LintersSettings.Varcheck
 		varnamelenCfg = &m.cfg.LintersSettings.Varnamelen
@@ -247,9 +247,6 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 		if stylecheckCfg != nil && stylecheckCfg.GoVersion != "" {
 			stylecheckCfg.GoVersion = trimGoVersion(m.cfg.Run.Go)
 		}
-		if unusedCfg != nil && unusedCfg.GoVersion == "" {
-			unusedCfg.GoVersion = trimGoVersion(m.cfg.Run.Go)
-		}
 	}
 
 	const megacheckName = "megacheck"
@@ -846,7 +843,7 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 			WithLoadForGoAnalysis().
 			WithURL("https://github.com/mvdan/unparam"),
 
-		linter.NewConfig(golinters.NewUnused(unusedCfg)).
+		linter.NewConfig(golinters.NewUnused(unusedCfg, staticcheckCfg)).
 			WithEnabledByDefault().
 			WithSince("v1.20.0").
 			WithLoadForGoAnalysis().