[CFE] Fix crash when metadata references locals in extension type

Having metadata on several variables means it has to be cloned which
(used to) crash.

Change-Id: I0ed1d4b51cec98adb23674d144d3970d3db9d69d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/398060
Reviewed-by: Johnni Winther <[email protected]>
Commit-Queue: Jens Johansen <[email protected]>

pkg/front_end/lib/src/kernel/body_builder.dart

@@ -3288,7 +3288,7 @@ class BodyBuilder extends StackListenerImpl
       VariableBuilder variableBuilder = declaration as VariableBuilder;
       if (constantContext != ConstantContext.none &&
           !variableBuilder.isConst &&
-          !_context.isConstructor &&
+           !(_context.isConstructor && inFieldInitializer) &&
           !libraryFeatures.constFunctions.isEnabled) {
         return new IncompleteErrorGenerator(
             this, nameToken, cfe.messageNotAConstantExpression);

pkg/front_end/testcases/regress/extension_type_metadata_references_variable.dart

@@ -0,0 +1,10 @@
+// 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 type Foo._(int _x) {
+  Foo(this._x, int bar){
+    @bar
+    int a1, a2;
+  }
+}

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

@@ -0,0 +1,42 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/extension_type_metadata_references_variable.dart:7:6: Error: Not a constant expression.
+//     @bar
+//      ^^^
+//
+// pkg/front_end/testcases/regress/extension_type_metadata_references_variable.dart:7:6: Error: This can't be used as an annotation; an annotation should be a reference to a compile-time constant variable, or a call to a constant constructor.
+//     @bar
+//      ^
+//
+import self as self;
+import "dart:core" as core;
+
+extension type Foo(core::int _x) {
+  abstract extension-type-member representation-field get _x() → core::int;
+  constructor _ = self::Foo|constructor#_;
+  constructor tearoff _ = self::Foo|constructor#_#_#tearOff;
+  constructor • = self::Foo|constructor#;
+  constructor tearoff • = self::Foo|constructor#_#new#tearOff;
+}
+static extension-type-member method Foo|constructor#_(core::int _x) → self::Foo% /* erasure=core::int, declared=! */ {
+  lowered final self::Foo% /* erasure=core::int, declared=! */ #this = _x;
+  return #this;
+}
+static extension-type-member method Foo|constructor#_#_#tearOff(core::int _x) → self::Foo% /* erasure=core::int, declared=! */
+  return self::Foo|constructor#_(_x);
+static extension-type-member method Foo|constructor#(core::int _x, core::int bar) → self::Foo% /* erasure=core::int, declared=! */ {
+  lowered final self::Foo% /* erasure=core::int, declared=! */ #this = _x;
+  {
+    @invalid-expression "pkg/front_end/testcases/regress/extension_type_metadata_references_variable.dart:7:6: Error: This can't be used as an annotation; an annotation should be a reference to a compile-time constant variable, or a call to a constant constructor.
+    @bar
+     ^" core::int a1;
+    @invalid-expression "pkg/front_end/testcases/regress/extension_type_metadata_references_variable.dart:7:6: Error: This can't be used as an annotation; an annotation should be a reference to a compile-time constant variable, or a call to a constant constructor.
+    @bar
+     ^" core::int a2;
+  }
+  return #this;
+}
+static extension-type-member method Foo|constructor#_#new#tearOff(core::int _x, core::int bar) → self::Foo% /* erasure=core::int, declared=! */
+  return self::Foo|constructor#(_x, bar);

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

@@ -0,0 +1,42 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/extension_type_metadata_references_variable.dart:7:6: Error: Not a constant expression.
+//     @bar
+//      ^^^
+//
+// pkg/front_end/testcases/regress/extension_type_metadata_references_variable.dart:7:6: Error: This can't be used as an annotation; an annotation should be a reference to a compile-time constant variable, or a call to a constant constructor.
+//     @bar
+//      ^
+//
+import self as self;
+import "dart:core" as core;
+
+extension type Foo(core::int _x) {
+  abstract extension-type-member representation-field get _x() → core::int;
+  constructor _ = self::Foo|constructor#_;
+  constructor tearoff _ = self::Foo|constructor#_#_#tearOff;
+  constructor • = self::Foo|constructor#;
+  constructor tearoff • = self::Foo|constructor#_#new#tearOff;
+}
+static extension-type-member method Foo|constructor#_(core::int _x) → self::Foo% /* erasure=core::int, declared=! */ {
+  lowered final self::Foo% /* erasure=core::int, declared=! */ #this = _x;
+  return #this;
+}
+static extension-type-member method Foo|constructor#_#_#tearOff(core::int _x) → self::Foo% /* erasure=core::int, declared=! */
+  return self::Foo|constructor#_(_x);
+static extension-type-member method Foo|constructor#(core::int _x, core::int bar) → self::Foo% /* erasure=core::int, declared=! */ {
+  lowered final self::Foo% /* erasure=core::int, declared=! */ #this = _x;
+  {
+    @invalid-expression "pkg/front_end/testcases/regress/extension_type_metadata_references_variable.dart:7:6: Error: This can't be used as an annotation; an annotation should be a reference to a compile-time constant variable, or a call to a constant constructor.
+    @bar
+     ^" core::int a1;
+    @invalid-expression "pkg/front_end/testcases/regress/extension_type_metadata_references_variable.dart:7:6: Error: This can't be used as an annotation; an annotation should be a reference to a compile-time constant variable, or a call to a constant constructor.
+    @bar
+     ^" core::int a2;
+  }
+  return #this;
+}
+static extension-type-member method Foo|constructor#_#new#tearOff(core::int _x, core::int bar) → self::Foo% /* erasure=core::int, declared=! */
+  return self::Foo|constructor#(_x, bar);

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

@@ -0,0 +1,19 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+extension type Foo(core::int _x) {
+  abstract extension-type-member representation-field get _x() → core::int;
+  constructor _ = self::Foo|constructor#_;
+  constructor tearoff _ = self::Foo|constructor#_#_#tearOff;
+  constructor • = self::Foo|constructor#;
+  constructor tearoff • = self::Foo|constructor#_#new#tearOff;
+}
+static extension-type-member method Foo|constructor#_(core::int _x) → self::Foo% /* erasure=core::int, declared=! */
+  ;
+static extension-type-member method Foo|constructor#_#_#tearOff(core::int _x) → self::Foo% /* erasure=core::int, declared=! */
+  return self::Foo|constructor#_(_x);
+static extension-type-member method Foo|constructor#(core::int _x, core::int bar) → self::Foo% /* erasure=core::int, declared=! */
+  ;
+static extension-type-member method Foo|constructor#_#new#tearOff(core::int _x, core::int bar) → self::Foo% /* erasure=core::int, declared=! */
+  return self::Foo|constructor#(_x, bar);

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

@@ -0,0 +1,42 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/extension_type_metadata_references_variable.dart:7:6: Error: Not a constant expression.
+//     @bar
+//      ^^^
+//
+// pkg/front_end/testcases/regress/extension_type_metadata_references_variable.dart:7:6: Error: This can't be used as an annotation; an annotation should be a reference to a compile-time constant variable, or a call to a constant constructor.
+//     @bar
+//      ^
+//
+import self as self;
+import "dart:core" as core;
+
+extension type Foo(core::int _x) {
+  abstract extension-type-member representation-field get _x() → core::int;
+  constructor _ = self::Foo|constructor#_;
+  constructor tearoff _ = self::Foo|constructor#_#_#tearOff;
+  constructor • = self::Foo|constructor#;
+  constructor tearoff • = self::Foo|constructor#_#new#tearOff;
+}
+static extension-type-member method Foo|constructor#_(core::int _x) → self::Foo% /* erasure=core::int, declared=! */ {
+  lowered final self::Foo% /* erasure=core::int, declared=! */ #this = _x;
+  return #this;
+}
+static extension-type-member method Foo|constructor#_#_#tearOff(core::int _x) → self::Foo% /* erasure=core::int, declared=! */
+  return self::Foo|constructor#_(_x);
+static extension-type-member method Foo|constructor#(core::int _x, core::int bar) → self::Foo% /* erasure=core::int, declared=! */ {
+  lowered final self::Foo% /* erasure=core::int, declared=! */ #this = _x;
+  {
+    @invalid-expression "pkg/front_end/testcases/regress/extension_type_metadata_references_variable.dart:7:6: Error: This can't be used as an annotation; an annotation should be a reference to a compile-time constant variable, or a call to a constant constructor.
+    @bar
+     ^" core::int a1;
+    @invalid-expression "pkg/front_end/testcases/regress/extension_type_metadata_references_variable.dart:7:6: Error: This can't be used as an annotation; an annotation should be a reference to a compile-time constant variable, or a call to a constant constructor.
+    @bar
+     ^" core::int a2;
+  }
+  return #this;
+}
+static extension-type-member method Foo|constructor#_#new#tearOff(core::int _x, core::int bar) → self::Foo% /* erasure=core::int, declared=! */
+  return self::Foo|constructor#(_x, bar);

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

@@ -0,0 +1,3 @@
+extension type Foo._(int _x) {
+  Foo(this._x, int bar) {}
+}

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

@@ -0,0 +1,3 @@
+extension type Foo._(int _x) {
+  Foo(this._x, int bar) {}
+}