[CFE] Skip processing of redirecting factories inside extensions as it will crash the compiler

Change-Id: I58b8cc2e62bd182bfb5c5a6a5efb33297c7dd5a9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/395520
Commit-Queue: Jens Johansen <jensj@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>

pkg/front_end/lib/src/source/source_loader.dart

@@ -2948,6 +2948,13 @@ severity: $severity
       if (redirectingFactoryBuilders != null) {
         for (RedirectingFactoryBuilder redirectingFactoryBuilder
             in redirectingFactoryBuilders) {
+          if (redirectingFactoryBuilder.parent.isExtension) {
+            // Extensions don't build their redirecting factories so we can't
+            // process them. Once they are added in
+            // [DeclarationNameSpaceBuilder.buildNameSpace] this skipping can
+            // likely be removed.
+            continue;
+          }
           redirectingFactoryBuilder.buildOutlineExpressions(
               classHierarchy, delayedDefaultValueCloners);
         }

pkg/front_end/lib/src/source/type_parameter_scope_builder.dart

@@ -1459,6 +1459,10 @@ class DeclarationNameSpaceBuilder {
         // TODO(johnniwinther): Handle constructors in extensions consistently.
         // Currently they are not part of the name space but still processed
         // for instance when inferring redirecting factories.
+        // They are part of the name space for extension types though.
+        // Note that we have to remove [RedirectingFactoryBuilder]s in
+        // [SourceLoader.inferRedirectingFactories] as we don't build them
+        // because we don't add them here.
         constructors: includeConstructors ? constructors : null);
   }
 }

pkg/front_end/testcases/regress/extension_with_redirecting_factory.dart

@@ -0,0 +1,7 @@
+// 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.
+
+extension Foo on String {
+  factory Foo({ this.fooX }) = Foobar;
+}

pkg/front_end/testcases/regress/extension_with_redirecting_factory.dart.strong.expect

@@ -0,0 +1,14 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/extension_with_redirecting_factory.dart:6:3: Error: Extensions can't declare constructors.
+// Try removing the constructor declaration.
+//   factory Foo({ this.fooX }) = Foobar;
+//   ^^^^^^^
+//
+import self as self;
+import "dart:core" as core;
+
+extension Foo on core::String {
+}

pkg/front_end/testcases/regress/extension_with_redirecting_factory.dart.strong.modular.expect

@@ -0,0 +1,14 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/extension_with_redirecting_factory.dart:6:3: Error: Extensions can't declare constructors.
+// Try removing the constructor declaration.
+//   factory Foo({ this.fooX }) = Foobar;
+//   ^^^^^^^
+//
+import self as self;
+import "dart:core" as core;
+
+extension Foo on core::String {
+}

pkg/front_end/testcases/regress/extension_with_redirecting_factory.dart.strong.outline.expect

@@ -0,0 +1,14 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/extension_with_redirecting_factory.dart:6:3: Error: Extensions can't declare constructors.
+// Try removing the constructor declaration.
+//   factory Foo({ this.fooX }) = Foobar;
+//   ^^^^^^^
+//
+import self as self;
+import "dart:core" as core;
+
+extension Foo on core::String {
+}

pkg/front_end/testcases/regress/extension_with_redirecting_factory.dart.strong.transformed.expect

@@ -0,0 +1,14 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/extension_with_redirecting_factory.dart:6:3: Error: Extensions can't declare constructors.
+// Try removing the constructor declaration.
+//   factory Foo({ this.fooX }) = Foobar;
+//   ^^^^^^^
+//
+import self as self;
+import "dart:core" as core;
+
+extension Foo on core::String {
+}

pkg/front_end/testcases/regress/extension_with_redirecting_factory.dart.textual_outline.expect

@@ -0,0 +1,3 @@
+extension Foo on String {
+  factory Foo({ this.fooX }) = Foobar;
+}

pkg/front_end/testcases/regress/extension_with_redirecting_factory.dart.textual_outline_modelled.expect

@@ -0,0 +1,3 @@
+extension Foo on String {
+  factory Foo({ this.fooX }) = Foobar;
+}