feat: option to not override severity from linters (#4452)

.golangci.reference.yml

@@ -2856,6 +2856,10 @@ severity:
   # Default: false
   case-sensitive: true
 
+  # Don't override severity defined by linters.
+  # Default: false
+  keep-linter-severity: true
+
   # When a list of severity rules are provided, severity information will be added to lint issues.
   # Severity rules have the same filtering capability as exclude rules
   # except you are allowed to specify one matcher per severity rule.

pkg/config/severity.go

@@ -11,6 +11,7 @@ type Severity struct {
 	Default            string         `mapstructure:"default-severity"`
 	CaseSensitive      bool           `mapstructure:"case-sensitive"`
 	Rules              []SeverityRule `mapstructure:"rules"`
+	KeepLinterSeverity bool           `mapstructure:"keep-linter-severity"` // TODO(ldez): in v2 should be changed to `Override`.
 }
 
 func (s *Severity) Validate() error {

pkg/lint/runner.go

@@ -332,6 +332,7 @@ func getSeverityRulesProcessor(cfg *config.Severity, log logutils.Log, files *fs
 		Default:       cfg.Default,
 		Rules:         severityRules,
 		CaseSensitive: cfg.CaseSensitive,
+		Override:      !cfg.KeepLinterSeverity,
 	}
 
 	return processors.NewSeverity(log.Child(logutils.DebugKeySeverityRules), files, severityOpts)

pkg/result/processors/severity.go

@@ -24,6 +24,7 @@ type SeverityOptions struct {
 	Default       string
 	Rules         []SeverityRule
 	CaseSensitive bool
+	Override      bool
 }
 
 type Severity struct {
@@ -35,6 +36,7 @@ type Severity struct {
 
 	defaultSeverity string
 	rules           []severityRule
+	override        bool
 }
 
 func NewSeverity(log logutils.Log, files *fsutils.Files, opts SeverityOptions) *Severity {
@@ -43,6 +45,7 @@ func NewSeverity(log logutils.Log, files *fsutils.Files, opts SeverityOptions) *
 		files:           files,
 		log:             log,
 		defaultSeverity: opts.Default,
+		override:        opts.Override,
 	}
 
 	prefix := "(?i)"
@@ -62,6 +65,10 @@ func (p *Severity) Process(issues []result.Issue) ([]result.Issue, error) {
 	}
 
 	return transformIssues(issues, func(i *result.Issue) *result.Issue {
+		if i.Severity != "" && !p.override {
+			return i
+		}
+
 		for _, rule := range p.rules {
 			rule := rule