[macros] Add DiagnosticException that macro implementations can throw to report a diagnostic.

[email protected]

Change-Id: I7546aa84f3e0b8423465dcb49d90a89df9231b84
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/350302
Reviewed-by: Konstantin Shcheglov <[email protected]>
Auto-Submit: Morgan :) <[email protected]>
Reviewed-by: Jake Macdonald <[email protected]>
Commit-Queue: Morgan :) <[email protected]>

Author: davidmorgan

pkg/_fe_analyzer_shared/lib/src/macros/api/exceptions.dart

@@ -4,6 +4,14 @@
 
 part of '../api.dart';
 
+/// Exception for use in macro implementations.
+///
+/// Throw to stop the current macro execution and report a [Diagnostic].
+class DiagnosticException implements Exception {
+  final Diagnostic diagnostic;
+  DiagnosticException(this.diagnostic);
+}
+
 /// Base class for exceptions thrown by the host implementation during macro
 /// execution.
 ///

pkg/_fe_analyzer_shared/lib/src/macros/executor/execute_macro.dart

@@ -59,8 +59,10 @@ Future<MacroExecutionResult> executeTypesMacro(
             'macro: $macro\ntarget: $target');
     }
   } catch (e, s) {
-    // Preserve `MacroException`s thrown by SDK tools.
-    if (e is MacroExceptionImpl) {
+    if (e is DiagnosticException) {
+      builder.report(e.diagnostic);
+    } else if (e is MacroExceptionImpl) {
+      // Preserve `MacroException`s thrown by SDK tools.
       builder.failWithException(e);
     } else {
       // Convert exceptions thrown by macro implementations into diagnostics.
@@ -137,8 +139,10 @@ Future<MacroExecutionResult> executeDeclarationsMacro(Macro macro,
             'macro: $macro\ntarget: $target');
     }
   } catch (e, s) {
-    // Preserve `MacroException`s thrown by SDK tools.
-    if (e is MacroExceptionImpl) {
+    if (e is DiagnosticException) {
+      builder.report(e.diagnostic);
+    } else if (e is MacroExceptionImpl) {
+      // Preserve `MacroException`s thrown by SDK tools.
       builder.failWithException(e);
     } else {
       // Convert exceptions thrown by macro implementations into diagnostics.
@@ -212,8 +216,10 @@ Future<MacroExecutionResult> executeDefinitionMacro(Macro macro, Object target,
             'macro: $macro\ntarget: $target');
     }
   } catch (e, s) {
-    // Preserve `MacroException`s thrown by SDK tools.
-    if (e is MacroExceptionImpl) {
+    if (e is DiagnosticException) {
+      builder.report(e.diagnostic);
+    } else if (e is MacroExceptionImpl) {
+      // Preserve `MacroException`s thrown by SDK tools.
       builder.failWithException(e);
     } else {
       // Convert exceptions thrown by macro implementations into diagnostics.

tests/language/macros/error/diagnostic_exception_test.dart

@@ -0,0 +1,14 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+// SharedOptions=--enable-experiment=macros
+
+import 'impl/throw_diagnostic_exception_macro.dart';
+
+@ThrowDiagnosticException(atTypeDeclaration: 'B', withMessage: 'failed here')
+class A {}
+
+class B {}
+//    ^
+// [analyzer] COMPILE_TIME_ERROR.MACRO_ERROR
+// [cfe] failed here

tests/language/macros/error/impl/throw_diagnostic_exception_macro.dart

@@ -0,0 +1,21 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+// ignore_for_file: deprecated_member_use
+import 'package:_fe_analyzer_shared/src/macros/api.dart';
+
+macro class ThrowDiagnosticException implements ClassDeclarationsMacro {
+  final String atTypeDeclaration;
+  final String withMessage;
+
+  const ThrowDiagnosticException({
+    required this.atTypeDeclaration, required this.withMessage});
+
+  Future<void> buildDeclarationsForClass(
+      ClassDeclaration clazz, MemberDeclarationBuilder builder) async {
+    final identifier = await builder.resolveIdentifier(clazz.library.uri, atTypeDeclaration);
+    final declaration = await builder.typeDeclarationOf(identifier);
+    throw DiagnosticException(Diagnostic(DiagnosticMessage(
+      withMessage, target: declaration.asDiagnosticTarget), Severity.error));
+  }
+}