[CFE] Fix crash on AmbiguousBuilder in handleUnaryPrefixExpression

Change-Id: I76fb3f77f9ffbbe6a7ecb892d3a5a21019b66371
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/394500
Reviewed-by: Johnni Winther <[email protected]>
Commit-Queue: Jens Johansen <[email protected]>

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

@@ -5826,9 +5826,11 @@ class BodyBuilder extends StackListenerImpl
       Name name = new Name(operator);
       if (receiver is Generator) {
         push(receiver.buildUnaryOperation(token, name));
+      } else if (receiver is Expression) {
+        push(forest.createUnary(fileOffset, name, receiver));
       } else {
-        assert(receiver is Expression);
-        push(forest.createUnary(fileOffset, name, receiver as Expression));
+        Expression value = toValue(receiver);
+        push(forest.createUnary(fileOffset, name, value));
       }
     }
   }

pkg/front_end/testcases/regress/ambiguous_builder_03.dart

@@ -0,0 +1,8 @@
+// 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.
+
+class Bar {
+  get foo => 42;
+  get foo => ~foo;
+}

pkg/front_end/testcases/regress/ambiguous_builder_03.dart.strong.expect

@@ -0,0 +1,25 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/ambiguous_builder_03.dart:7:7: Error: 'foo' is already declared in this scope.
+//   get foo => ~foo;
+//       ^^^
+// pkg/front_end/testcases/regress/ambiguous_builder_03.dart:6:7: Context: Previous declaration of 'foo'.
+//   get foo => 42;
+//       ^^^
+//
+// pkg/front_end/testcases/regress/ambiguous_builder_03.dart:7:15: Error: Can't use 'foo' because it is declared more than once.
+//   get foo => ~foo;
+//               ^
+//
+import self as self;
+import "dart:core" as core;
+
+class Bar extends core::Object {
+  synthetic constructor •() → self::Bar
+    : super core::Object::•()
+    ;
+  get foo() → dynamic
+    return 42;
+}

pkg/front_end/testcases/regress/ambiguous_builder_03.dart.strong.modular.expect

@@ -0,0 +1,25 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/ambiguous_builder_03.dart:7:7: Error: 'foo' is already declared in this scope.
+//   get foo => ~foo;
+//       ^^^
+// pkg/front_end/testcases/regress/ambiguous_builder_03.dart:6:7: Context: Previous declaration of 'foo'.
+//   get foo => 42;
+//       ^^^
+//
+// pkg/front_end/testcases/regress/ambiguous_builder_03.dart:7:15: Error: Can't use 'foo' because it is declared more than once.
+//   get foo => ~foo;
+//               ^
+//
+import self as self;
+import "dart:core" as core;
+
+class Bar extends core::Object {
+  synthetic constructor •() → self::Bar
+    : super core::Object::•()
+    ;
+  get foo() → dynamic
+    return 42;
+}

pkg/front_end/testcases/regress/ambiguous_builder_03.dart.strong.outline.expect

@@ -0,0 +1,20 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/ambiguous_builder_03.dart:7:7: Error: 'foo' is already declared in this scope.
+//   get foo => ~foo;
+//       ^^^
+// pkg/front_end/testcases/regress/ambiguous_builder_03.dart:6:7: Context: Previous declaration of 'foo'.
+//   get foo => 42;
+//       ^^^
+//
+import self as self;
+import "dart:core" as core;
+
+class Bar extends core::Object {
+  synthetic constructor •() → self::Bar
+    ;
+  get foo() → dynamic
+    ;
+}

pkg/front_end/testcases/regress/ambiguous_builder_03.dart.strong.transformed.expect

@@ -0,0 +1,25 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/ambiguous_builder_03.dart:7:7: Error: 'foo' is already declared in this scope.
+//   get foo => ~foo;
+//       ^^^
+// pkg/front_end/testcases/regress/ambiguous_builder_03.dart:6:7: Context: Previous declaration of 'foo'.
+//   get foo => 42;
+//       ^^^
+//
+// pkg/front_end/testcases/regress/ambiguous_builder_03.dart:7:15: Error: Can't use 'foo' because it is declared more than once.
+//   get foo => ~foo;
+//               ^
+//
+import self as self;
+import "dart:core" as core;
+
+class Bar extends core::Object {
+  synthetic constructor •() → self::Bar
+    : super core::Object::•()
+    ;
+  get foo() → dynamic
+    return 42;
+}

pkg/front_end/testcases/regress/ambiguous_builder_03.dart.textual_outline.expect

@@ -0,0 +1,4 @@
+class Bar {
+  get foo => 42;
+  get foo => ~foo;
+}

pkg/front_end/testcases/regress/ambiguous_builder_03.dart.textual_outline_modelled.expect

@@ -0,0 +1,4 @@
+class Bar {
+  get foo => 42;
+  get foo => ~foo;
+}