Check enums in switch cases.

pkg/compiler/lib/src/warnings.dart

Index: pkg/compiler/lib/src/warnings.dart
diff --git a/pkg/compiler/lib/src/warnings.dart b/pkg/compiler/lib/src/warnings.dart
index 5d872d0106329df0c54e6cad4f495e7a2b76494a..c3a56542121c59005d8c7ea85541e35b4ffa053e 100644
--- a/pkg/compiler/lib/src/warnings.dart
+++ b/pkg/compiler/lib/src/warnings.dart
@@ -804,9 +804,9 @@ main() => new C();
       howToFix: "Try making '#{enumType}' a normal class or removing the "
         "'extends' clause.",
       examples: const ["""
-enum Enum {}
-class A extends Enum {}
-main() => new A();"""]);
+enum Enum { A }
+class B extends Enum {}
+main() => new B();"""]);
 
   static const MessageKind CANNOT_IMPLEMENT_ENUM = const MessageKind(
       "Class '#{className}' can't implement the type '#{enumType}' "
@@ -815,9 +815,9 @@ main() => new A();"""]);
       howToFix: "Try making '#{enumType}' a normal class or removing the "
         "type from the 'implements' clause.",
       examples: const ["""
-enum Enum {}
-class A implements Enum {}
-main() => new A();"""]);
+enum Enum { A }
+class B implements Enum {}
+main() => new B();"""]);
 
   static const MessageKind CANNOT_MIXIN_ENUM = const MessageKind(
       "Class '#{className}' can't mixin the type '#{enumType}' because it "
@@ -826,9 +826,9 @@ main() => new A();"""]);
       howToFix: "Try making '#{enumType}' a normal class or removing the "
         "type from the 'with' clause.",
       examples: const ["""
-enum Enum {}
-class A extends Object with Enum {}
-main() => new A();"""]);
+enum Enum { A }
+class B extends Object with Enum {}
+main() => new B();"""]);
 
   static const MessageKind CANNOT_INSTANTIATE_ENUM = const MessageKind(
       "Enum type '#{enumName}' cannot be instantiated.",
@@ -836,11 +836,38 @@ main() => new A();"""]);
       howToFix: "Try making '#{enumType}' a normal class or use an enum "
                 "constant.",
       examples: const ["""
-enum Enum {}
+enum Enum { A }
 main() => new Enum(0);""", """
-enum Enum {}
+enum Enum { A }
 main() => const Enum(0);"""]);
 
+  static const MessageKind EMPTY_ENUM_DECLARATION = const MessageKind(
+      "Enum '#{enumName}' must contain at least one value.",
+      options: const ['--enable-enum'],
+      howToFix: "Try adding an enum constant or making #{enumName} a "
+                "normal class.",
+      examples: const ["""
+enum Enum {}
+main() { Enum e; }"""]);
+
+  static const MessageKind MISSING_ENUM_CASES = const MessageKind(
+      "Missing enum constants in switch statement: #{enumValues}.",
+      options: const ['--enable-enum'],
+      howToFix: "Try adding the missing constants or a default case.",
+      examples: const ["""
+enum Enum { A, B }
+main() {
+  switch (Enum.A) {
+  case Enum.B: break;
+  }
+}""", """
+enum Enum { A, B, C }
+main() {
+  switch (Enum.A) {
+  case Enum.B: break;
+  }
+}"""]);
+
   static const MessageKind DUPLICATE_EXTENDS_IMPLEMENTS = const MessageKind(
       "'#{type}' can not be both extended and implemented.");