Fix for issue 22110

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

Index: pkg/analyzer/lib/src/generated/resolver.dart
diff --git a/pkg/analyzer/lib/src/generated/resolver.dart b/pkg/analyzer/lib/src/generated/resolver.dart
index 02781e4e70f4c8839152e05ebf97a94ac3b83b52..9f3ab6db8bc4e02b0522cb0702245e1e9c2fc947 100644
--- a/pkg/analyzer/lib/src/generated/resolver.dart
+++ b/pkg/analyzer/lib/src/generated/resolver.dart
@@ -4202,6 +4202,18 @@ class ExitDetector extends GeneralizingAstVisitor<bool> {
           return false;
         }
       }
+      // All of the members exit, determine whether there are possible cases
+      // that are not caught by the members.
+      DartType type = node.expression == null ? null : node.expression.bestType;
+      if (type is InterfaceType) {
+        ClassElement element = type.element;
+        if (element != null && element.isEnum) {
+          // If some of the enum values are not covered, then a warning will
+          // have already been generated, so there's no point in generating a
+          // hint.
+          return true;
+        }
+      }
       return hasDefault;
     } finally {
       _enclosingBlockContainsBreak = outerBreakValue;