rules: support inverted path match (#3617)

Author: pohly

.golangci.reference.yml

@@ -2323,6 +2323,11 @@ issues:
         - dupl
         - gosec
 
+    # Run some linter only for test files by excluding its issues for everything else.
+    - path-except: _test\.go
+      linters:
+        - forbidigo
+
     # Exclude known linters from partially hard-vendored code,
     # which is impossible to exclude via `nolint` comments.
     # `/` will be replaced by current OS file path separator to properly work on Windows.

docs/src/docs/usage/false-positives.mdx

@@ -81,6 +81,18 @@ issues:
         - goconst
 ```
 
+The opposite, excluding reports **except** for specific paths, is also possible.
+In the following example, only test files get checked:
+
+```yml
+issues:
+  exclude-rules:
+    - path-except: '(.+)_test\.go'
+      linters:
+        - funlen
+        - goconst
+```
+
 In the following example, all the reports related to the files (`skip-files`) are excluded:
 
 ```yml

pkg/config/issues.go

@@ -125,21 +125,25 @@ type ExcludeRule struct {
 	BaseRule `mapstructure:",squash"`
 }
 
-func (e ExcludeRule) Validate() error {
+func (e *ExcludeRule) Validate() error {
 	return e.BaseRule.Validate(excludeRuleMinConditionsCount)
 }
 
 type BaseRule struct {
-	Linters []string
-	Path    string
-	Text    string
-	Source  string
+	Linters    []string
+	Path       string
+	PathExcept string `mapstructure:"path-except"`
+	Text       string
+	Source     string
 }
 
-func (b BaseRule) Validate(minConditionsCount int) error {
+func (b *BaseRule) Validate(minConditionsCount int) error {
 	if err := validateOptionalRegex(b.Path); err != nil {
 		return fmt.Errorf("invalid path regex: %v", err)
 	}
+	if err := validateOptionalRegex(b.PathExcept); err != nil {
+		return fmt.Errorf("invalid path-except regex: %v", err)
+	}
 	if err := validateOptionalRegex(b.Text); err != nil {
 		return fmt.Errorf("invalid text regex: %v", err)
 	}
@@ -150,7 +154,10 @@ func (b BaseRule) Validate(minConditionsCount int) error {
 	if len(b.Linters) > 0 {
 		nonBlank++
 	}
-	if b.Path != "" {
+	// Filtering by path counts as one condition, regardless how it is done (one or both).
+	// Otherwise, a rule with Path and PathExcept set would pass validation
+	// whereas before the introduction of path-except that wouldn't have been precise enough.
+	if b.Path != "" || b.PathExcept != "" {
 		nonBlank++
 	}
 	if b.Text != "" {
@@ -160,7 +167,7 @@ func (b BaseRule) Validate(minConditionsCount int) error {
 		nonBlank++
 	}
 	if nonBlank < minConditionsCount {
-		return fmt.Errorf("at least %d of (text, source, path, linters) should be set", minConditionsCount)
+		return fmt.Errorf("at least %d of (text, source, path[-except],  linters) should be set", minConditionsCount)
 	}
 	return nil
 }

pkg/lint/runner.go

@@ -276,10 +276,11 @@ func getExcludeRulesProcessor(cfg *config.Issues, log logutils.Log, files *fsuti
 	for _, r := range cfg.ExcludeRules {
 		excludeRules = append(excludeRules, processors.ExcludeRule{
 			BaseRule: processors.BaseRule{
-				Text:    r.Text,
-				Source:  r.Source,
-				Path:    r.Path,
-				Linters: r.Linters,
+				Text:       r.Text,
+				Source:     r.Source,
+				Path:       r.Path,
+				PathExcept: r.PathExcept,
+				Linters:    r.Linters,
 			},
 		})
 	}
@@ -319,10 +320,11 @@ func getSeverityRulesProcessor(cfg *config.Severity, log logutils.Log, files *fs
 		severityRules = append(severityRules, processors.SeverityRule{
 			Severity: r.Severity,
 			BaseRule: processors.BaseRule{
-				Text:    r.Text,
-				Source:  r.Source,
-				Path:    r.Path,
-				Linters: r.Linters,
+				Text:       r.Text,
+				Source:     r.Source,
+				Path:       r.Path,
+				PathExcept: r.PathExcept,
+				Linters:    r.Linters,
 			},
 		})
 	}

pkg/result/processors/base_rule.go

@@ -9,21 +9,23 @@ import (
 )
 
 type BaseRule struct {
-	Text    string
-	Source  string
-	Path    string
-	Linters []string
+	Text       string
+	Source     string
+	Path       string
+	PathExcept string
+	Linters    []string
 }
 
 type baseRule struct {
-	text    *regexp.Regexp
-	source  *regexp.Regexp
-	path    *regexp.Regexp
-	linters []string
+	text       *regexp.Regexp
+	source     *regexp.Regexp
+	path       *regexp.Regexp
+	pathExcept *regexp.Regexp
+	linters    []string
 }
 
 func (r *baseRule) isEmpty() bool {
-	return r.text == nil && r.source == nil && r.path == nil && len(r.linters) == 0
+	return r.text == nil && r.source == nil && r.path == nil && r.pathExcept == nil && len(r.linters) == 0
 }
 
 func (r *baseRule) match(issue *result.Issue, files *fsutils.Files, log logutils.Log) bool {
@@ -36,6 +38,9 @@ func (r *baseRule) match(issue *result.Issue, files *fsutils.Files, log logutils
 	if r.path != nil && !r.path.MatchString(files.WithPathPrefix(issue.FilePath())) {
 		return false
 	}
+	if r.pathExcept != nil && r.pathExcept.MatchString(issue.FilePath()) {
+		return false
+	}
 	if len(r.linters) != 0 && !r.matchLinter(issue) {
 		return false
 	}

pkg/result/processors/exclude_rules.go

@@ -47,6 +47,10 @@ func createRules(rules []ExcludeRule, prefix string) []excludeRule {
 			path := fsutils.NormalizePathInRegex(rule.Path)
 			parsedRule.path = regexp.MustCompile(path)
 		}
+		if rule.PathExcept != "" {
+			pathExcept := fsutils.NormalizePathInRegex(rule.PathExcept)
+			parsedRule.pathExcept = regexp.MustCompile(pathExcept)
+		}
 		parsedRules = append(parsedRules, parsedRule)
 	}
 	return parsedRules

pkg/result/processors/exclude_rules_test.go

@@ -34,6 +34,12 @@ func TestExcludeRulesMultiple(t *testing.T) {
 				Path: `_test\.go`,
 			},
 		},
+		{
+			BaseRule: BaseRule{
+				Text:       "^nontestonly$",
+				PathExcept: `_test\.go`,
+			},
+		},
 		{
 			BaseRule: BaseRule{
 				Source:  "^//go:generate ",
@@ -42,13 +48,16 @@ func TestExcludeRulesMultiple(t *testing.T) {
 		},
 	}, files, nil)
 
+	//nolint:dupl
 	cases := []issueTestCase{
 		{Path: "e.go", Text: "exclude", Linter: "linter"},
 		{Path: "e.go", Text: "some", Linter: "linter"},
 		{Path: "e_test.go", Text: "normal", Linter: "testlinter"},
 		{Path: "e_Test.go", Text: "normal", Linter: "testlinter"},
 		{Path: "e_test.go", Text: "another", Linter: "linter"},
 		{Path: "e_test.go", Text: "testonly", Linter: "linter"},
+		{Path: "e.go", Text: "nontestonly", Linter: "linter"},
+		{Path: "e_test.go", Text: "nontestonly", Linter: "linter"},
 		{Path: filepath.Join("testdata", "exclude_rules.go"), Line: 3, Linter: "lll"},
 	}
 	var issues []result.Issue
@@ -69,6 +78,7 @@ func TestExcludeRulesMultiple(t *testing.T) {
 		{Path: "e.go", Text: "some", Linter: "linter"},
 		{Path: "e_Test.go", Text: "normal", Linter: "testlinter"},
 		{Path: "e_test.go", Text: "another", Linter: "linter"},
+		{Path: "e_test.go", Text: "nontestonly", Linter: "linter"},
 	}
 	assert.Equal(t, expectedCases, resultingCases)
 }
@@ -172,6 +182,7 @@ func TestExcludeRulesCaseSensitiveMultiple(t *testing.T) {
 		},
 	}, files, nil)
 
+	//nolint:dupl
 	cases := []issueTestCase{
 		{Path: "e.go", Text: "exclude", Linter: "linter"},
 		{Path: "e.go", Text: "excLude", Linter: "linter"},

pkg/result/processors/severity_rules.go

@@ -52,6 +52,10 @@ func createSeverityRules(rules []SeverityRule, prefix string) []severityRule {
 			path := fsutils.NormalizePathInRegex(rule.Path)
 			parsedRule.path = regexp.MustCompile(path)
 		}
+		if rule.PathExcept != "" {
+			pathExcept := fsutils.NormalizePathInRegex(rule.PathExcept)
+			parsedRule.pathExcept = regexp.MustCompile(pathExcept)
+		}
 		parsedRules = append(parsedRules, parsedRule)
 	}
 	return parsedRules

pkg/result/processors/severity_rules_test.go

@@ -39,6 +39,13 @@ func TestSeverityRulesMultiple(t *testing.T) {
 				Path: `_test\.go`,
 			},
 		},
+		{
+			Severity: "info",
+			BaseRule: BaseRule{
+				Text:       "^nontestonly$",
+				PathExcept: `_test\.go`,
+			},
+		},
 		{
 			BaseRule: BaseRule{
 				Source:  "^//go:generate ",
@@ -72,6 +79,8 @@ func TestSeverityRulesMultiple(t *testing.T) {
 		{Path: "ssl.go", Text: "ssl", Linter: "gosec"},
 		{Path: "e.go", Text: "some", Linter: "linter"},
 		{Path: "e_test.go", Text: "testonly", Linter: "testlinter"},
+		{Path: "e.go", Text: "nontestonly", Linter: "testlinter"},
+		{Path: "e_test.go", Text: "nontestonly", Linter: "testlinter"},
 		{Path: filepath.Join("testdata", "exclude_rules.go"), Line: 3, Linter: "lll"},
 		{Path: filepath.Join("testdata", "severity_rules.go"), Line: 3, Linter: "invalidgo"},
 		{Path: "someotherlinter.go", Text: "someotherlinter", Linter: "someotherlinter"},
@@ -97,6 +106,8 @@ func TestSeverityRulesMultiple(t *testing.T) {
 		{Path: "ssl.go", Text: "ssl", Linter: "gosec", Severity: "info"},
 		{Path: "e.go", Text: "some", Linter: "linter", Severity: "info"},
 		{Path: "e_test.go", Text: "testonly", Linter: "testlinter", Severity: "info"},
+		{Path: "e.go", Text: "nontestonly", Linter: "testlinter", Severity: "info"},       // matched
+		{Path: "e_test.go", Text: "nontestonly", Linter: "testlinter", Severity: "error"}, // not matched
 		{Path: filepath.Join("testdata", "exclude_rules.go"), Line: 3, Linter: "lll", Severity: "error"},
 		{Path: filepath.Join("testdata", "severity_rules.go"), Line: 3, Linter: "invalidgo", Severity: "info"},
 		{Path: "someotherlinter.go", Text: "someotherlinter", Linter: "someotherlinter", Severity: "info"},

test/testdata/configs/path-except.yml

@@ -0,0 +1,13 @@
+linters-settings:
+  forbidigo:
+    forbid:
+      - fmt\.Print.*
+      - time.Sleep(# no sleeping!)?
+
+issues:
+  exclude-rules:
+    # Apply forbidigo only to test files, exclude
+    # it everywhere else.
+    - path-except: _test\.go
+      linters:
+        - forbidigo