Improve messages involving empty cycles

Change-Id: I4a6732bcce9ddb98cd00e60e8d46fae1dd4b9599 Reviewed-on: https://dart-review.googlesource.com/76500 Commit-Queue: Peter von der Ahé <ahe@google.com> Reviewed-by: Jens Johansen <jensj@google.com>
flutter · Sep 26, 2018 · a3aa0c1 · a3aa0c1
1 parent 48d1b5e
commit a3aa0c1
Show file tree

Hide file tree

Showing 5 changed files with 86 additions and 10 deletions.
diff --git a/pkg/front_end/lib/src/fasta/fasta_codes_generated.dart b/pkg/front_end/lib/src/fasta/fasta_codes_generated.dart
@@ -1942,6 +1942,52 @@ ${num3} ms/libraries.""",
       });
 }
 
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<
+    Message Function(
+        String
+            name)> templateDirectCycleInTypeVariables = const Template<
+        Message Function(String name)>(
+    messageTemplate: r"""Type '#name' can't use itself as a bound.""",
+    tipTemplate:
+        r"""Try breaking the cycle by removing at least on of the 'extends' clauses in the cycle.""",
+    withArguments: _withArgumentsDirectCycleInTypeVariables);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Message Function(String name)> codeDirectCycleInTypeVariables =
+    const Code<Message Function(String name)>(
+        "DirectCycleInTypeVariables", templateDirectCycleInTypeVariables,
+        analyzerCode: "TYPE_PARAMETER_SUPERTYPE_OF_ITS_BOUND");
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsDirectCycleInTypeVariables(String name) {
+  return new Message(codeDirectCycleInTypeVariables,
+      message: """Type '${name}' can't use itself as a bound.""",
+      tip:
+          """Try breaking the cycle by removing at least on of the 'extends' clauses in the cycle.""",
+      arguments: {'name': name});
+}
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<Message Function(String name)>
+    templateDirectCyclicClassHierarchy =
+    const Template<Message Function(String name)>(
+        messageTemplate: r"""'#name' can't use itself as a supertype.""",
+        withArguments: _withArgumentsDirectCyclicClassHierarchy);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Message Function(String name)> codeDirectCyclicClassHierarchy =
+    const Code<Message Function(String name)>(
+        "DirectCyclicClassHierarchy", templateDirectCyclicClassHierarchy,
+        analyzerCode: "RECURSIVE_INTERFACE_INHERITANCE");
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsDirectCyclicClassHierarchy(String name) {
+  return new Message(codeDirectCyclicClassHierarchy,
+      message: """'${name}' can't use itself as a supertype.""",
+      arguments: {'name': name});
+}
+
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Code<Null> codeDirectiveAfterDeclaration =
     messageDirectiveAfterDeclaration;

diff --git a/pkg/front_end/lib/src/fasta/source/outline_builder.dart b/pkg/front_end/lib/src/fasta/source/outline_builder.dart
@@ -30,6 +30,7 @@ import '../fasta_codes.dart'
         messageStaticConstructor,
         messageTypedefNotFunction,
         templateCycleInTypeVariables,
+        templateDirectCycleInTypeVariables,
         templateDuplicatedParameterName,
         templateDuplicatedParameterNameCause,
         templateOperatorMinusParameterMismatch,
@@ -1376,12 +1377,11 @@ class OutlineBuilder extends StackListener {
               via.add(bound.name);
               bound = typeVariablesByName[bound.bound.name];
             }
-            String involvedString = via.join("', '");
-            addProblem(
-                templateCycleInTypeVariables.withArguments(
-                    builder.name, involvedString),
-                builder.charOffset,
-                builder.name.length);
+            Message message = via.isEmpty
+                ? templateDirectCycleInTypeVariables.withArguments(builder.name)
+                : templateCycleInTypeVariables.withArguments(
+                    builder.name, via.join("', '"));
+            addProblem(message, builder.charOffset, builder.name.length);
           }
         }
       }

diff --git a/pkg/front_end/lib/src/fasta/source/source_loader.dart b/pkg/front_end/lib/src/fasta/source/source_loader.dart
@@ -73,6 +73,7 @@ import '../fasta_codes.dart'
         templateIllegalMixinDueToConstructorsCause,
         templateInternalProblemUriMissingScheme,
         templateSourceOutlineSummary,
+        templateDirectCyclicClassHierarchy,
         templateUntranslatableUri;
 
 import '../fasta_codes.dart' as fasta_codes;
@@ -584,9 +585,14 @@ class SourceLoader<L> extends Loader<L> {
                 .toList()
                   ..sort())
             .join("', '");
-        messages[templateCyclicClassHierarchy
-            .withArguments(cls.fullNameForErrors, involvedString)
-            .withLocation(cls.fileUri, cls.charOffset, noLength)] = cls;
+        LocatedMessage message = involvedString.isEmpty
+            ? templateDirectCyclicClassHierarchy
+                .withArguments(cls.fullNameForErrors)
+                .withLocation(cls.fileUri, cls.charOffset, noLength)
+            : templateCyclicClassHierarchy
+                .withArguments(cls.fullNameForErrors, involvedString)
+                .withLocation(cls.fileUri, cls.charOffset, noLength);
+        messages[message] = cls;
       });
 
       // Report all classes involved in a cycle, sorted to ensure stability as

diff --git a/pkg/front_end/messages.status b/pkg/front_end/messages.status
@@ -88,7 +88,9 @@ CovariantAndStatic/script1: Fail
 CovariantAndStatic/script2: Fail
 CovariantMember/script1: Fail
 CovariantMember/script2: Fail
-CyclicClassHierarchy/example: Fail
+CycleInTypeVariables/script1: Fail # We report an error for each type variable involved in the cycle.
+CyclicClassHierarchy/script1: Fail # We report an error for each class involved in the cycle.
+CyclicClassHierarchy/script2: Fail # We report an error for each class involved in the cycle.
 CyclicTypedef/example: Fail
 DeferredAfterPrefix/example: Fail
 DeferredPrefixDuplicated/example: Fail

diff --git a/pkg/front_end/messages.yaml b/pkg/front_end/messages.yaml
@@ -1663,6 +1663,21 @@ DuplicatedImportInType:
 CyclicClassHierarchy:
   template: "'#name' is a supertype of itself via '#string'."
   analyzerCode: RECURSIVE_INTERFACE_INHERITANCE
+  script:
+    - |
+      class A extends B {}
+      class B extends A {}
+    - |
+      class A implements B {}
+      class B implements A {}
+
+DirectCyclicClassHierarchy:
+  template: "'#name' can't use itself as a supertype."
+  analyzerCode: RECURSIVE_INTERFACE_INHERITANCE
+  script:
+    - "class C = Object with C;"
+    - "class C extends C {}"
+    - "class C implements C {}"
 
 ExtendingEnum:
   template: "'#name' is an enum and can't be extended or implemented."
@@ -2841,6 +2856,13 @@ CycleInTypeVariables:
   template: "Type '#name' is a bound of itself via '#string'."
   tip: "Try breaking the cycle by removing at least on of the 'extends' clauses in the cycle."
   analyzerCode: TYPE_PARAMETER_SUPERTYPE_OF_ITS_BOUND
+  script:
+    - "foo<A extends B, B extends A>() {}"
+
+DirectCycleInTypeVariables:
+  template: "Type '#name' can't use itself as a bound."
+  tip: "Try breaking the cycle by removing at least on of the 'extends' clauses in the cycle."
+  analyzerCode: TYPE_PARAMETER_SUPERTYPE_OF_ITS_BOUND
   script:
     - "foo<A extends A>() {}"