feat: remove warning when the config file is explicitly stdin (golangci#3740)

Author: ldez

pkg/config/reader.go

@@ -72,13 +72,21 @@ func (r *FileReader) parseConfig() error {
 		return nil
 	}
 
-	usedConfigFile, err := fsutils.ShortestRelPath(usedConfigFile, "")
-	if err != nil {
-		r.log.Warnf("Can't pretty print config file path: %s", err)
+	if usedConfigFile == os.Stdin.Name() {
+		usedConfigFile = ""
+		r.log.Infof("Reading config file stdin")
+	} else {
+		var err error
+		usedConfigFile, err = fsutils.ShortestRelPath(usedConfigFile, "")
+		if err != nil {
+			r.log.Warnf("Can't pretty print config file path: %v", err)
+		}
+
+		r.log.Infof("Used config file %s", usedConfigFile)
 	}
-	r.log.Infof("Used config file %s", usedConfigFile)
-	usedConfigDir := filepath.Dir(usedConfigFile)
-	if usedConfigDir, err = filepath.Abs(usedConfigDir); err != nil {
+
+	usedConfigDir, err := filepath.Abs(filepath.Dir(usedConfigFile))
+	if err != nil {
 		return errors.New("can't get config directory")
 	}
 	r.cfg.cfgDir = usedConfigDir