config: add validation for exclude rules

pkg/config/config.go

@@ -1,6 +1,9 @@
 package config
 
 import (
+	"errors"
+	"fmt"
+	"regexp"
 	"time"
 )
 
@@ -233,6 +236,37 @@ type ExcludeRule struct {
 	Text    string
 }
 
+func validateOptionalRegex(value string) error {
+	if value == "" {
+		return nil
+	}
+	_, err := regexp.Compile(value)
+	return err
+}
+
+func (e ExcludeRule) Validate() error {
+	if err := validateOptionalRegex(e.Path); err != nil {
+		return fmt.Errorf("invalid path regex: %v", err)
+	}
+	if err := validateOptionalRegex(e.Text); err != nil {
+		return fmt.Errorf("invalid text regex: %v", err)
+	}
+	nonBlank := 0
+	if len(e.Linters) > 0 {
+		nonBlank++
+	}
+	if e.Path != "" {
+		nonBlank++
+	}
+	if e.Text != "" {
+		nonBlank++
+	}
+	if nonBlank < 2 {
+		return errors.New("at least 2 of (text, path, linters) should be set")
+	}
+	return nil
+}
+
 type Issues struct {
 	ExcludePatterns    []string      `mapstructure:"exclude"`
 	ExcludeRules       []ExcludeRule `mapstructure:"exclude-rules"`

pkg/config/reader.go

@@ -105,6 +105,11 @@ func (r *FileReader) validateConfig() error {
 	if c.Run.IsVerbose {
 		return errors.New("can't set run.verbose option with config: only on command-line")
 	}
+	for i, rule := range c.Issues.ExcludeRules {
+		if err := rule.Validate(); err != nil {
+			return fmt.Errorf("error in exclude rule #%d: %v", i, err)
+		}
+	}
 
 	return nil
 }

pkg/result/processors/exclude_rules.go

@@ -55,7 +55,6 @@ func NewExcludeRules(rules []ExcludeRule) *ExcludeRules {
 		if rule.Path != "" {
 			parsedRule.path = regexp.MustCompile(rule.Path)
 		}
-		// TODO: Forbid text-only, linter-only or path-only exclude rule.
 		r.rules = append(r.rules, parsedRule)
 	}
 	return r