feat: explain typecheck and remove it from the linter list (golangci#3929)

Author: ldez

docs/src/docs/usage/faq.mdx

@@ -32,3 +32,22 @@ The same as the Go team (the 2 last minor versions)
 
 Because the first run caches type information. All subsequent runs will be fast.
 Usually this options is used during development on local machine and compilation was already performed.
+
+## Why do you have `typecheck` errors?
+
+`typecheck` is like the front-end of a Go compiler, parses and type-checks Go code, it manages compilation errors.
+
+It cannot be disabled because of that.
+
+Of course, this is just as good as the compiler itself and a lot of compilation issues will not properly show where in the code your error lies.
+
+`typecheck` is not a real linter, it's just a way to parse compiling errors (produced by the `types.Checker`) and some linter errors.
+
+If there are `typecheck` errors, golangci-lint will not able to produce other reports because that kind of error doesn't allow it to perform analysis.
+
+How to troubleshoot:
+
+- [ ] Ensure the version of `golangci-lint` is built with a compatible version of Go.
+- [ ] Ensure dependencies are up-to-date with `go mod tidy`.
+- [ ] Ensure building works with `go run ./...`/`go build ./...` - whole package.
+- [ ] If using CGO, ensure all require system libraries are installed.

pkg/commands/help.go

@@ -63,6 +63,10 @@ func printLinterConfigs(lcs []*linter.Config) {
 func (e *Executor) executeLintersHelp(_ *cobra.Command, _ []string) {
 	var enabledLCs, disabledLCs []*linter.Config
 	for _, lc := range e.DBManager.GetAllSupportedLinterConfigs() {
+		if lc.Internal {
+			continue
+		}
+
 		if lc.EnabledByDefault {
 			enabledLCs = append(enabledLCs, lc)
 		} else {
@@ -78,8 +82,12 @@ func (e *Executor) executeLintersHelp(_ *cobra.Command, _ []string) {
 	color.Green("\nLinters presets:")
 	for _, p := range e.DBManager.AllPresets() {
 		linters := e.DBManager.GetAllLinterConfigsForPreset(p)
-		linterNames := make([]string, 0, len(linters))
+		var linterNames []string
 		for _, lc := range linters {
+			if lc.Internal {
+				continue
+			}
+
 			linterNames = append(linterNames, lc.Name())
 		}
 		sort.Strings(linterNames)

pkg/commands/linters.go

@@ -29,14 +29,22 @@ func (e *Executor) executeLinters(_ *cobra.Command, _ []string) error {
 	}
 
 	color.Green("Enabled by your configuration linters:\n")
-	enabledLinters := make([]*linter.Config, 0, len(enabledLintersMap))
-	for _, linter := range enabledLintersMap {
-		enabledLinters = append(enabledLinters, linter)
+	var enabledLinters []*linter.Config
+	for _, lc := range enabledLintersMap {
+		if lc.Internal {
+			continue
+		}
+
+		enabledLinters = append(enabledLinters, lc)
 	}
 	printLinterConfigs(enabledLinters)
 
 	var disabledLCs []*linter.Config
 	for _, lc := range e.DBManager.GetAllSupportedLinterConfigs() {
+		if lc.Internal {
+			continue
+		}
+
 		if enabledLintersMap[lc.Name()] == nil {
 			disabledLCs = append(disabledLCs, lc)
 		}

pkg/lint/linter/config.go

@@ -42,6 +42,7 @@ type Config struct {
 	AlternativeNames []string
 
 	OriginalURL     string // URL of original (not forked) repo, needed for autogenerated README
+	Internal        bool   // Internal linters cannot be disabled (ex: typecheck).
 	CanAutoFix      bool
 	IsSlow          bool
 	DoesChangeTypes bool
@@ -55,6 +56,11 @@ func (lc *Config) WithEnabledByDefault() *Config {
 	return lc
 }
 
+func (lc *Config) WithInternal() *Config {
+	lc.Internal = true
+	return lc
+}
+
 func (lc *Config) ConsiderSlow() *Config {
 	lc.IsSlow = true
 	return lc

pkg/lint/lintersdb/enabled_set.go

@@ -31,8 +31,10 @@ func NewEnabledSet(m *Manager, v *Validator, log logutils.Log, cfg *config.Confi
 	}
 }
 
+//nolint:gocyclo // the complexity cannot be reduced.
 func (es EnabledSet) build(lcfg *config.Linters, enabledByDefaultLinters []*linter.Config) map[string]*linter.Config {
 	es.debugf("Linters config: %#v", lcfg)
+
 	resultLintersSet := map[string]*linter.Config{}
 	switch {
 	case len(lcfg.Presets) != 0:
@@ -78,6 +80,14 @@ func (es EnabledSet) build(lcfg *config.Linters, enabledByDefaultLinters []*lint
 		}
 	}
 
+	// typecheck is not a real linter and cannot be disabled.
+	if _, ok := resultLintersSet["typecheck"]; !ok && (es.cfg == nil || !es.cfg.InternalCmdTest) {
+		for _, lc := range es.m.GetLinterConfigs("typecheck") {
+			// it's important to use lc.Name() nor name because name can be alias
+			resultLintersSet[lc.Name()] = lc
+		}
+	}
+
 	return resultLintersSet
 }
 
@@ -134,8 +144,8 @@ func (es EnabledSet) GetOptimizedLinters() ([]*linter.Config, error) {
 func (es EnabledSet) combineGoAnalysisLinters(linters map[string]*linter.Config) {
 	var goanalysisLinters []*goanalysis.Linter
 	goanalysisPresets := map[string]bool{}
-	for _, linter := range linters {
-		lnt, ok := linter.Linter.(*goanalysis.Linter)
+	for _, lc := range linters {
+		lnt, ok := lc.Linter.(*goanalysis.Linter)
 		if !ok {
 			continue
 		}
@@ -144,7 +154,7 @@ func (es EnabledSet) combineGoAnalysisLinters(linters map[string]*linter.Config)
 			continue
 		}
 		goanalysisLinters = append(goanalysisLinters, lnt)
-		for _, p := range linter.InPresets {
+		for _, p := range lc.InPresets {
 			goanalysisPresets[p] = true
 		}
 	}
@@ -197,6 +207,10 @@ func (es EnabledSet) combineGoAnalysisLinters(linters map[string]*linter.Config)
 func (es EnabledSet) verbosePrintLintersStatus(lcs map[string]*linter.Config) {
 	var linterNames []string
 	for _, lc := range lcs {
+		if lc.Internal {
+			continue
+		}
+
 		linterNames = append(linterNames, lc.Name())
 	}
 	sort.StringSlice(linterNames).Sort()

pkg/lint/lintersdb/enabled_set_test.go

@@ -16,81 +16,86 @@ func TestGetEnabledLintersSet(t *testing.T) {
 		def  []string // enabled by default linters
 		exp  []string // alphabetically ordered enabled linter names
 	}
+
 	allMegacheckLinterNames := []string{"gosimple", "staticcheck", "unused"}
+
 	cases := []cs{
 		{
 			cfg: config.Linters{
 				Disable: []string{"megacheck"},
 			},
 			name: "disable all linters from megacheck",
 			def:  allMegacheckLinterNames,
-			exp:  nil, // all disabled
+			exp:  []string{"typecheck"}, // all disabled
 		},
 		{
 			cfg: config.Linters{
 				Disable: []string{"staticcheck"},
 			},
 			name: "disable only staticcheck",
 			def:  allMegacheckLinterNames,
-			exp:  []string{"gosimple", "unused"},
+			exp:  []string{"gosimple", "typecheck", "unused"},
 		},
 		{
 			name: "don't merge into megacheck",
 			def:  allMegacheckLinterNames,
-			exp:  allMegacheckLinterNames,
+			exp:  []string{"gosimple", "staticcheck", "typecheck", "unused"},
 		},
 		{
 			name: "expand megacheck",
 			cfg: config.Linters{
 				Enable: []string{"megacheck"},
 			},
 			def: nil,
-			exp: allMegacheckLinterNames,
+			exp: []string{"gosimple", "staticcheck", "typecheck", "unused"},
 		},
 		{
 			name: "don't disable anything",
-			def:  []string{"gofmt", "govet"},
-			exp:  []string{"gofmt", "govet"},
+			def:  []string{"gofmt", "govet", "typecheck"},
+			exp:  []string{"gofmt", "govet", "typecheck"},
 		},
 		{
 			name: "enable gosec by gas alias",
 			cfg: config.Linters{
 				Enable: []string{"gas"},
 			},
-			exp: []string{"gosec"},
+			exp: []string{"gosec", "typecheck"},
 		},
 		{
 			name: "enable gosec by primary name",
 			cfg: config.Linters{
 				Enable: []string{"gosec"},
 			},
-			exp: []string{"gosec"},
+			exp: []string{"gosec", "typecheck"},
 		},
 		{
 			name: "enable gosec by both names",
 			cfg: config.Linters{
 				Enable: []string{"gosec", "gas"},
 			},
-			exp: []string{"gosec"},
+			exp: []string{"gosec", "typecheck"},
 		},
 		{
 			name: "disable gosec by gas alias",
 			cfg: config.Linters{
 				Disable: []string{"gas"},
 			},
 			def: []string{"gosec"},
+			exp: []string{"typecheck"},
 		},
 		{
 			name: "disable gosec by primary name",
 			cfg: config.Linters{
 				Disable: []string{"gosec"},
 			},
 			def: []string{"gosec"},
+			exp: []string{"typecheck"},
 		},
 	}
 
 	m := NewManager(nil, nil)
 	es := NewEnabledSet(m, NewValidator(m), nil, nil)
+
 	for _, c := range cases {
 		c := c
 		t.Run(c.name, func(t *testing.T) {

pkg/lint/lintersdb/manager.go

@@ -804,6 +804,7 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 			WithURL("https://github.com/moricho/tparallel"),
 
 		linter.NewConfig(golinters.NewTypecheck()).
+			WithInternal().
 			WithEnabledByDefault().
 			WithSince("v1.3.0").
 			WithLoadForGoAnalysis().

pkg/result/processors/nolint_test.go

@@ -279,11 +279,15 @@ func TestNolintUnused(t *testing.T) {
 	createProcessor := func(t *testing.T, log *logutils.MockLog, enabledLinters []string) *Nolint {
 		enabledSetLog := logutils.NewMockLog()
 		enabledSetLog.On("Infof", "Active %d linters: %s", len(enabledLinters), enabledLinters)
+
 		cfg := &config.Config{Linters: config.Linters{DisableAll: true, Enable: enabledLinters}}
 		dbManager := lintersdb.NewManager(cfg, nil)
+
 		enabledLintersSet := lintersdb.NewEnabledSet(dbManager, lintersdb.NewValidator(dbManager), enabledSetLog, cfg)
+
 		enabledLintersMap, err := enabledLintersSet.GetEnabledLintersMap()
 		assert.NoError(t, err)
+
 		return NewNolint(log, dbManager, enabledLintersMap)
 	}
 

scripts/expand_website_templates/main.go

@@ -238,6 +238,10 @@ func getLintersListMarkdown(enabled bool) string {
 	var neededLcs []*linter.Config
 	lcs := lintersdb.NewManager(nil, nil).GetAllSupportedLinterConfigs()
 	for _, lc := range lcs {
+		if lc.Internal {
+			continue
+		}
+
 		if lc.EnabledByDefault == enabled {
 			neededLcs = append(neededLcs, lc)
 		}

test/enabled_linters_test.go

@@ -170,6 +170,10 @@ func getEnabledByDefaultLinters() []string {
 	ebdl := lintersdb.NewManager(nil, nil).GetAllEnabledByDefaultLinters()
 	var ret []string
 	for _, lc := range ebdl {
+		if lc.Internal {
+			continue
+		}
+
 		ret = append(ret, lc.Name())
 	}