Improve error message (issue 25113)

pkg/analyzer/lib/src/generated/parser.dart

Index: pkg/analyzer/lib/src/generated/parser.dart
diff --git a/pkg/analyzer/lib/src/generated/parser.dart b/pkg/analyzer/lib/src/generated/parser.dart
index 8863fa95e90b0e30cd546d2f4dcb0a9f604f9632..8ec719a7de2a7dba50572859c073aef72a8ca412 100644
--- a/pkg/analyzer/lib/src/generated/parser.dart
+++ b/pkg/analyzer/lib/src/generated/parser.dart
@@ -5459,9 +5459,12 @@ class Parser {
         if (constKeyword != null) {
           _reportErrorForNode(
               ParserErrorCode.CONST_CONSTRUCTOR_WITH_BODY, body);
-        } else if (!bodyAllowed) {
+        } else if (externalKeyword != null) {
           _reportErrorForNode(
               ParserErrorCode.EXTERNAL_CONSTRUCTOR_WITH_BODY, body);
+        } else if (!bodyAllowed) {
+          _reportErrorForNode(
+              ParserErrorCode.REDIRECTING_CONSTRUCTOR_WITH_BODY, body);
         }
       }
     }
@@ -9829,6 +9832,10 @@ class ParserErrorCode extends ErrorCode {
       const ParserErrorCode('POSITIONAL_PARAMETER_OUTSIDE_GROUP',
           "Positional parameters must be enclosed in square brackets ('[' and ']')");
 
+  static const ParserErrorCode REDIRECTING_CONSTRUCTOR_WITH_BODY =
+      const ParserErrorCode('REDIRECTING_CONSTRUCTOR_WITH_BODY',
+          "Redirecting constructors cannot have a body");
+
   static const ParserErrorCode REDIRECTION_IN_NON_FACTORY_CONSTRUCTOR =
       const ParserErrorCode('REDIRECTION_IN_NON_FACTORY_CONSTRUCTOR',
           "Only factory constructor can specify '=' redirection.");