Report compile-time error on disallowed metadata values.

Closes #14548

R=karlklose@google.com

Review URL: https://codereview.chromium.org/1510863004.

pkg/compiler/lib/src/diagnostics/messages.dart

@@ -256,6 +256,8 @@ enum MessageKind {
   INVALID_CONTINUE,
   INVALID_FOR_IN,
   INVALID_INITIALIZER,
+  INVALID_METADATA,
+  INVALID_METADATA_GENERIC,
   INVALID_OVERRIDDEN_FIELD,
   INVALID_OVERRIDDEN_GETTER,
   INVALID_OVERRIDDEN_METHOD,
@@ -2866,6 +2868,31 @@ main() => new C();
           "The getter '#{name}' is implicitly declared by this field "
           "in class '#{class}'."),
 
+      MessageKind.INVALID_METADATA:
+        const MessageTemplate(MessageKind.INVALID_METADATA,
+          "A metadata annotation must be either a reference to a compile-time "
+          "constant variable or a call to a constant constructor.",
+          howToFix:
+            "Try using a different constant value or referencing it through a "
+            "constant variable.",
+          examples: const [
+'@Object main() {}',
+'@print main() {}']),
+
+      MessageKind.INVALID_METADATA_GENERIC:
+        const MessageTemplate(MessageKind.INVALID_METADATA_GENERIC,
+          "A metadata annotation using a constant constructor cannot use type "
+          "arguments.",
+          howToFix:
+            "Try removing the type arguments or referencing the constant "
+            "through a constant variable.",
+          examples: const ['''
+class C<T> {
+  const C();
+}
+@C<int>() main() {}
+''']),
+
       MessageKind.EQUAL_MAP_ENTRY_KEY:
         const MessageTemplate(MessageKind.EQUAL_MAP_ENTRY_KEY,
           "An entry with the same key already exists in the map.",

pkg/compiler/lib/src/resolution/resolution.dart

@@ -21,6 +21,11 @@ import '../compiler.dart' show
     Compiler;
 import '../compile_time_constants.dart' show
     ConstantCompiler;
+import '../constants/expressions.dart' show
+    ConstantExpression,
+    ConstantExpressionKind,
+    ConstructedConstantExpression,
+    ErroneousConstantExpression;
 import '../constants/values.dart' show
     ConstantValue;
 import '../core_types.dart' show
@@ -1061,8 +1066,29 @@ class ResolverTask extends CompilerTask {
       node.accept(visitor);
       // TODO(johnniwinther): Avoid passing the [TreeElements] to
       // [compileMetadata].
-      annotation.constant =
-          constantCompiler.compileMetadata(annotation, node, registry.mapping);
+      ConstantExpression constant = constantCompiler.compileMetadata(
+          annotation, node, registry.mapping);
+      switch (constant.kind) {
+        case ConstantExpressionKind.CONSTRUCTED:
+          ConstructedConstantExpression constructedConstant = constant;
+          if (constructedConstant.type.isGeneric) {
+            // Const constructor calls cannot have type arguments.
+            // TODO(24312): Remove this.
+            reporter.reportErrorMessage(
+                node, MessageKind.INVALID_METADATA_GENERIC);
+            constant = new ErroneousConstantExpression();
+          }
+          break;
+        case ConstantExpressionKind.VARIABLE:
+        case ConstantExpressionKind.ERRONEOUS:
+          break;
+        default:
+          reporter.reportErrorMessage(node, MessageKind.INVALID_METADATA);
+          constant = new ErroneousConstantExpression();
+          break;
+      }
+      annotation.constant = constant;
+
       constantCompiler.evaluate(annotation.constant);
       // TODO(johnniwinther): Register the relation between the annotation
       // and the annotated element instead. This will allow the backend to

tests/compiler/dart2js/mirrors_helper.dart

@@ -15,10 +15,9 @@ main() {
 }
 
 /// Singleline doc comment.
-@Metadata // This is intentionally the type literal.
+@Metadata(null)
 // Singleline comment 1.
 // Singleline comment 2.
-@Metadata(null)
 @Metadata(true)
 @Metadata(false)
 @Metadata(0)

tests/compiler/dart2js/mirrors_test.dart

@@ -169,7 +169,7 @@ void testFoo(MirrorSystem system, LibraryMirror helperLibrary,
 
   var metadataList = fooClass.metadata;
   Expect.isNotNull(metadataList);
-  Expect.equals(16, metadataList.length);
+  Expect.equals(14, metadataList.length);
   var metadataListIndex = 0;
   var metadata;
 
@@ -192,28 +192,17 @@ void testFoo(MirrorSystem system, LibraryMirror helperLibrary,
   Expect.stringEquals(
       "Singleline doc comment.", metadata.trimmedText);
 
-  // @Metadata
+  // @Metadata(null)
   metadata = metadataList[metadataListIndex++];
+  var metadataType = metadata.type;
   Expect.isTrue(metadata is InstanceMirror);
   Expect.isFalse(metadata.hasReflectee);
   Expect.throws(() => metadata.reflectee, (_) => true);
-  Expect.isTrue(metadata is TypeInstanceMirror);
-  var metadataType = metadata.representedType;
-  Expect.isNotNull(metadataType);
-  Expect.equals(#Metadata, metadataType.simpleName);
-
-  // // This is intentionally the type literal.
-  metadata = metadataList[metadataListIndex++];
-  Expect.isTrue(metadata is InstanceMirror);
-  Expect.isFalse(metadata.hasReflectee);
-  Expect.throws(() => metadata.reflectee, (_) => true);
-  Expect.isTrue(metadata is CommentInstanceMirror);
-  Expect.equals(commentType.originalDeclaration, metadata.type);
-  Expect.isFalse(metadata.isDocComment);
-  Expect.stringEquals(
-      "// This is intentionally the type literal.", metadata.text);
-  Expect.stringEquals(
-      "This is intentionally the type literal.", metadata.trimmedText);
+  Expect.isTrue(metadataType.isOriginalDeclaration);
+  InstanceMirror data = metadata.getField(#data);
+  Expect.isNotNull(data);
+  Expect.isTrue(data.hasReflectee);
+  Expect.isNull(data.reflectee);
 
   // Singleline comment 1.
   metadata = metadataList[metadataListIndex++];
@@ -241,17 +230,6 @@ void testFoo(MirrorSystem system, LibraryMirror helperLibrary,
   Expect.stringEquals(
       "Singleline comment 2.", metadata.trimmedText);
 
-  // @Metadata(null)
-  metadata = metadataList[metadataListIndex++];
-  Expect.isTrue(metadata is InstanceMirror);
-  Expect.isFalse(metadata.hasReflectee);
-  Expect.throws(() => metadata.reflectee, (_) => true);
-  Expect.equals(metadataType.originalDeclaration, metadata.type);
-  InstanceMirror data = metadata.getField(#data);
-  Expect.isNotNull(data);
-  Expect.isTrue(data.hasReflectee);
-  Expect.isNull(data.reflectee);
-
   // @Metadata(true)
   metadata = metadataList[metadataListIndex++];
   Expect.isTrue(metadata is InstanceMirror);
@@ -398,7 +376,7 @@ void testFoo(MirrorSystem system, LibraryMirror helperLibrary,
   // leading comment.
   Expect.equals(376, fooClassLocation.offset, "Unexpected offset");
   // Expect the location to end with the class body.
-  Expect.equals(351, fooClassLocation.length, "Unexpected length");
+  Expect.equals(298, fooClassLocation.length, "Unexpected length");
   Expect.equals(18, fooClassLocation.line, "Unexpected line");
   Expect.equals(1, fooClassLocation.column, "Unexpected column");
 

tests/lib/lib.status

@@ -64,12 +64,6 @@ mirrors/library_uri_io_test: SkipByDesign # Uses dart:io.
 mirrors/load_library_test: RuntimeError # Issue 6335
 mirrors/local_function_is_static_test: RuntimeError # Issue 6335
 mirrors/lru_test: Skip # dart2js_native/lru_test is used instead
-mirrors/metadata_allowed_values_test/01: MissingCompileTimeError # Issue 14548
-mirrors/metadata_allowed_values_test/05: MissingCompileTimeError # Issue 14548
-mirrors/metadata_allowed_values_test/10: MissingCompileTimeError # Issue 14548
-mirrors/metadata_allowed_values_test/11: MissingCompileTimeError # Issue 14548
-mirrors/metadata_allowed_values_test/13: MissingCompileTimeError # Issue 14548
-mirrors/metadata_allowed_values_test/14: MissingCompileTimeError # Issue 14548
 mirrors/metadata_scope_test/none: CompileTimeError # Issue 10905
 mirrors/method_mirror_name_test: RuntimeError # Issue 6335
 mirrors/method_mirror_properties_test: RuntimeError # Issue 11861