[CFE] Fix crash on invalid this references

Change-Id: If6a323a7cc2defab3a0f7844b948719c49fef483
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/395301
Reviewed-by: Johnni Winther <[email protected]>
Commit-Queue: Jens Johansen <[email protected]>

Author: jensjoha

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

@@ -3292,6 +3292,10 @@ class BodyBuilder extends StackListenerImpl
           // semantics, such parameters introduces a new parameter with that
           // name that should be resolved here.
           !_context.isConstructor) {
+        if (declaration.isExtensionTypeInstanceMember) {
+          return new IncompleteErrorGenerator(
+              this, nameToken, fasta.messageNotAConstantExpression);
+        }
         addProblem(
             fasta.messageNotAConstantExpression, nameOffset, nameToken.length);
       }
@@ -7178,8 +7182,13 @@ class BodyBuilder extends StackListenerImpl
     debugEvent("ThisExpression");
     if (context.isScopeReference && isDeclarationInstanceContext) {
       if (thisVariable != null && !inConstructorInitializer) {
-        push(_createReadOnlyVariableAccess(thisVariable!, token,
-            offsetForToken(token), 'this', ReadOnlyAccessKind.ExtensionThis));
+        if (constantContext != ConstantContext.none) {
+          push(new IncompleteErrorGenerator(
+              this, token, fasta.messageThisAsIdentifier));
+        } else {
+          push(_createReadOnlyVariableAccess(thisVariable!, token,
+              offsetForToken(token), 'this', ReadOnlyAccessKind.ExtensionThis));
+        }
       } else {
         push(new ThisAccessGenerator(this, token, inInitializerLeftHandSide,
             inFieldInitializer, inLateFieldInitializer));

pkg/front_end/test/spell_checking_list_tests.txt

@@ -348,6 +348,7 @@ foos
 forbidden
 forces
 foreground
+forgot
 forrest
 forth
 forty
@@ -577,6 +578,7 @@ oo
 oobar
 oocf
 ooo
+oops
 oovf
 opacity
 operate

pkg/front_end/testcases/regress/invalid_this_reference_01.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(String x) {
+  int x2 = 42;
+
+  @x2
+  int? a, b;
+}

pkg/front_end/testcases/regress/invalid_this_reference_01.dart.strong.expect

@@ -0,0 +1,49 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_01.dart:6:7: Error: Extension types can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int x2 = 42;
+//       ^^
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_01.dart:9:8: Error: Extension types can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? a, b;
+//        ^
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: Error: Not a constant expression.
+//   @x2
+//    ^^
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: 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.
+//   @x2
+//    ^
+//
+import self as self;
+import "dart:core" as core;
+
+extension type Foo(core::String x) {
+  abstract extension-type-member representation-field get x() → core::String;
+  abstract extension-type-member representation-field get x2() → core::int;
+  @invalid-expression "pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: 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.
+  @x2
+   ^" in invalid-expression "pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: Error: Not a constant expression.
+  @x2
+   ^^"
+  abstract extension-type-member representation-field get a() → core::int?;
+  @invalid-expression "pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: 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.
+  @x2
+   ^" in invalid-expression "pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: Error: Not a constant expression.
+  @x2
+   ^^"
+  abstract extension-type-member representation-field get b() → core::int?;
+  constructor • = self::Foo|constructor#;
+  constructor tearoff • = self::Foo|constructor#_#new#tearOff;
+}
+static extension-type-member method Foo|constructor#(core::String x) → self::Foo% /* erasure=core::String, declared=! */ {
+  lowered final self::Foo% /* erasure=core::String, declared=! */ #this = x;
+  return #this;
+}
+static extension-type-member method Foo|constructor#_#new#tearOff(core::String x) → self::Foo% /* erasure=core::String, declared=! */
+  return self::Foo|constructor#(x);

pkg/front_end/testcases/regress/invalid_this_reference_01.dart.strong.modular.expect

@@ -0,0 +1,49 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_01.dart:6:7: Error: Extension types can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int x2 = 42;
+//       ^^
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_01.dart:9:8: Error: Extension types can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? a, b;
+//        ^
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: Error: Not a constant expression.
+//   @x2
+//    ^^
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: 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.
+//   @x2
+//    ^
+//
+import self as self;
+import "dart:core" as core;
+
+extension type Foo(core::String x) {
+  abstract extension-type-member representation-field get x() → core::String;
+  abstract extension-type-member representation-field get x2() → core::int;
+  @invalid-expression "pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: 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.
+  @x2
+   ^" in invalid-expression "pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: Error: Not a constant expression.
+  @x2
+   ^^"
+  abstract extension-type-member representation-field get a() → core::int?;
+  @invalid-expression "pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: 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.
+  @x2
+   ^" in invalid-expression "pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: Error: Not a constant expression.
+  @x2
+   ^^"
+  abstract extension-type-member representation-field get b() → core::int?;
+  constructor • = self::Foo|constructor#;
+  constructor tearoff • = self::Foo|constructor#_#new#tearOff;
+}
+static extension-type-member method Foo|constructor#(core::String x) → self::Foo% /* erasure=core::String, declared=! */ {
+  lowered final self::Foo% /* erasure=core::String, declared=! */ #this = x;
+  return #this;
+}
+static extension-type-member method Foo|constructor#_#new#tearOff(core::String x) → self::Foo% /* erasure=core::String, declared=! */
+  return self::Foo|constructor#(x);

pkg/front_end/testcases/regress/invalid_this_reference_01.dart.strong.outline.expect

@@ -0,0 +1,47 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_01.dart:6:7: Error: Extension types can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int x2 = 42;
+//       ^^
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_01.dart:9:8: Error: Extension types can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? a, b;
+//        ^
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: Error: Not a constant expression.
+//   @x2
+//    ^^
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: 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.
+//   @x2
+//    ^
+//
+import self as self;
+import "dart:core" as core;
+
+extension type Foo(core::String x) {
+  abstract extension-type-member representation-field get x() → core::String;
+  abstract extension-type-member representation-field get x2() → core::int;
+  @invalid-expression "pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: 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.
+  @x2
+   ^" in invalid-expression "pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: Error: Not a constant expression.
+  @x2
+   ^^"
+  abstract extension-type-member representation-field get a() → core::int?;
+  @invalid-expression "pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: 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.
+  @x2
+   ^" in invalid-expression "pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: Error: Not a constant expression.
+  @x2
+   ^^"
+  abstract extension-type-member representation-field get b() → core::int?;
+  constructor • = self::Foo|constructor#;
+  constructor tearoff • = self::Foo|constructor#_#new#tearOff;
+}
+static extension-type-member method Foo|constructor#(core::String x) → self::Foo% /* erasure=core::String, declared=! */
+  ;
+static extension-type-member method Foo|constructor#_#new#tearOff(core::String x) → self::Foo% /* erasure=core::String, declared=! */
+  return self::Foo|constructor#(x);

pkg/front_end/testcases/regress/invalid_this_reference_01.dart.strong.transformed.expect

@@ -0,0 +1,49 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_01.dart:6:7: Error: Extension types can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int x2 = 42;
+//       ^^
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_01.dart:9:8: Error: Extension types can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? a, b;
+//        ^
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: Error: Not a constant expression.
+//   @x2
+//    ^^
+//
+// pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: 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.
+//   @x2
+//    ^
+//
+import self as self;
+import "dart:core" as core;
+
+extension type Foo(core::String x) {
+  abstract extension-type-member representation-field get x() → core::String;
+  abstract extension-type-member representation-field get x2() → core::int;
+  @invalid-expression "pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: 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.
+  @x2
+   ^" in invalid-expression "pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: Error: Not a constant expression.
+  @x2
+   ^^"
+  abstract extension-type-member representation-field get a() → core::int?;
+  @invalid-expression "pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: 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.
+  @x2
+   ^" in invalid-expression "pkg/front_end/testcases/regress/invalid_this_reference_01.dart:8:4: Error: Not a constant expression.
+  @x2
+   ^^"
+  abstract extension-type-member representation-field get b() → core::int?;
+  constructor • = self::Foo|constructor#;
+  constructor tearoff • = self::Foo|constructor#_#new#tearOff;
+}
+static extension-type-member method Foo|constructor#(core::String x) → self::Foo% /* erasure=core::String, declared=! */ {
+  lowered final self::Foo% /* erasure=core::String, declared=! */ #this = x;
+  return #this;
+}
+static extension-type-member method Foo|constructor#_#new#tearOff(core::String x) → self::Foo% /* erasure=core::String, declared=! */
+  return self::Foo|constructor#(x);

pkg/front_end/testcases/regress/invalid_this_reference_01.dart.textual_outline.expect

@@ -0,0 +1,5 @@
+extension type Foo(String x) {
+  int x2 = 42;
+  @x2
+  int? a, b;
+}

pkg/front_end/testcases/regress/invalid_this_reference_01.dart.textual_outline_modelled.expect

@@ -0,0 +1,5 @@
+extension type Foo(String x) {
+  @x2
+  int? a, b;
+  int x2 = 42;
+}

pkg/front_end/testcases/regress/invalid_this_reference_02.dart

@@ -0,0 +1,11 @@
+// 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(String x) {
+  static const int x1 = 42;
+  int x2 = 42;
+
+  int bar1({int baz = x2}) => 42;
+  int bar2({int baz = x /* oops forgot the 1 */}) => 42;
+}