[cfe] Infer constness in enum element initializers

Part of #47453

Closes #48233

Change-Id: Iaa75ccac6622e874da5f6e5feb053fc19a220936
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/232382
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Commit-Queue: Chloe Stefantsova <cstefantsova@google.com>

pkg/front_end/lib/src/fasta/source/source_enum_builder.dart

@@ -614,7 +614,7 @@ class SourceEnumBuilder extends SourceClassBuilder {
             // be built via a body builder to detect potential errors.
             bodyBuilder = library.loader.createBodyBuilderForOutlineExpression(
                 library, this, this, scope, fileUri);
-            bodyBuilder.constantContext = ConstantContext.required;
+            bodyBuilder.constantContext = ConstantContext.inferred;
           }
 
           if (enumConstantInfo.argumentsBeginToken != null) {

pkg/front_end/testcases/enhanced_enums/issue48232.dart

@@ -0,0 +1,10 @@
+// Copyright (c) 2022, 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.
+
+enum E {
+    v([]); // No error.
+  const E(_);
+}
+
+main() {}

pkg/front_end/testcases/enhanced_enums/issue48232.dart.strong.expect

@@ -0,0 +1,28 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+class E extends core::_Enum /*isEnum*/  {
+  static const field core::List<self::E> values = #C4;
+  static const field self::E v = #C3;
+  const constructor •(core::int index, core::String name, dynamic _) → self::E
+    : super core::_Enum::•(index, name)
+    ;
+  method toString() → core::String
+    return "E.${this.{core::_Enum::_name}{core::String}}";
+}
+static method main() → dynamic {}
+
+constants  {
+  #C1 = 0
+  #C2 = "v"
+  #C3 = self::E {index:#C1, _name:#C2}
+  #C4 = <self::E>[#C3]
+}
+
+
+Constructor coverage from constants:
+org-dartlang-testcase:///issue48232.dart:
+- E. (from org-dartlang-testcase:///issue48232.dart:7:9)
+- _Enum. (from org-dartlang-sdk:///sdk/lib/core/enum.dart:103:9)
+- Object. (from org-dartlang-sdk:///sdk/lib/core/object.dart:25:9)

pkg/front_end/testcases/enhanced_enums/issue48232.dart.strong.transformed.expect

@@ -0,0 +1,28 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+class E extends core::_Enum /*isEnum*/  {
+  static const field core::List<self::E> values = #C4;
+  static const field self::E v = #C3;
+  const constructor •(core::int index, core::String name, dynamic _) → self::E
+    : super core::_Enum::•(index, name)
+    ;
+  method toString() → core::String
+    return "E.${this.{core::_Enum::_name}{core::String}}";
+}
+static method main() → dynamic {}
+
+constants  {
+  #C1 = 0
+  #C2 = "v"
+  #C3 = self::E {index:#C1, _name:#C2}
+  #C4 = <self::E>[#C3]
+}
+
+
+Constructor coverage from constants:
+org-dartlang-testcase:///issue48232.dart:
+- E. (from org-dartlang-testcase:///issue48232.dart:7:9)
+- _Enum. (from org-dartlang-sdk:///sdk/lib/core/enum.dart:103:9)
+- Object. (from org-dartlang-sdk:///sdk/lib/core/object.dart:25:9)

pkg/front_end/testcases/enhanced_enums/issue48232.dart.textual_outline.expect

@@ -0,0 +1,2 @@
+enum E { v([]); const E(_); }
+main() {}

pkg/front_end/testcases/enhanced_enums/issue48232.dart.weak.expect

@@ -0,0 +1,28 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+class E extends core::_Enum /*isEnum*/  {
+  static const field core::List<self::E> values = #C4;
+  static const field self::E v = #C3;
+  const constructor •(core::int index, core::String name, dynamic _) → self::E
+    : super core::_Enum::•(index, name)
+    ;
+  method toString() → core::String
+    return "E.${this.{core::_Enum::_name}{core::String}}";
+}
+static method main() → dynamic {}
+
+constants  {
+  #C1 = 0
+  #C2 = "v"
+  #C3 = self::E {index:#C1, _name:#C2}
+  #C4 = <self::E*>[#C3]
+}
+
+
+Constructor coverage from constants:
+org-dartlang-testcase:///issue48232.dart:
+- E. (from org-dartlang-testcase:///issue48232.dart:7:9)
+- _Enum. (from org-dartlang-sdk:///sdk/lib/core/enum.dart:103:9)
+- Object. (from org-dartlang-sdk:///sdk/lib/core/object.dart:25:9)

pkg/front_end/testcases/enhanced_enums/issue48232.dart.weak.modular.expect

@@ -0,0 +1,28 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+class E extends core::_Enum /*isEnum*/  {
+  static const field core::List<self::E> values = #C4;
+  static const field self::E v = #C3;
+  const constructor •(core::int index, core::String name, dynamic _) → self::E
+    : super core::_Enum::•(index, name)
+    ;
+  method toString() → core::String
+    return "E.${this.{core::_Enum::_name}{core::String}}";
+}
+static method main() → dynamic {}
+
+constants  {
+  #C1 = 0
+  #C2 = "v"
+  #C3 = self::E {index:#C1, _name:#C2}
+  #C4 = <self::E*>[#C3]
+}
+
+
+Constructor coverage from constants:
+org-dartlang-testcase:///issue48232.dart:
+- E. (from org-dartlang-testcase:///issue48232.dart:7:9)
+- _Enum. (from org-dartlang-sdk:///sdk/lib/core/enum.dart:103:9)
+- Object. (from org-dartlang-sdk:///sdk/lib/core/object.dart:25:9)

pkg/front_end/testcases/enhanced_enums/issue48232.dart.weak.outline.expect

@@ -0,0 +1,21 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+class E extends core::_Enum /*isEnum*/  {
+  static const field core::List<self::E> values = const <self::E>[self::E::v];
+  static const field self::E v = const self::E::•(0, "v", const <dynamic>[]);
+  const constructor •(core::int index, core::String name, dynamic _) → self::E
+    : super core::_Enum::•(index, name)
+    ;
+  method toString() → core::String
+    return "E.${this.{core::_Enum::_name}{core::String}}";
+}
+static method main() → dynamic
+  ;
+
+
+Extra constant evaluation status:
+Evaluated: ListLiteral @ org-dartlang-testcase:///issue48232.dart:5:6 -> ListConstant(const <E*>[const E{_Enum.index: 0, _Enum._name: "v"}])
+Evaluated: ConstructorInvocation @ org-dartlang-testcase:///issue48232.dart:6:5 -> InstanceConstant(const E{_Enum.index: 0, _Enum._name: "v"})
+Extra constant evaluation: evaluated: 7, effectively constant: 2

pkg/front_end/testcases/enhanced_enums/issue48232.dart.weak.transformed.expect

@@ -0,0 +1,28 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+class E extends core::_Enum /*isEnum*/  {
+  static const field core::List<self::E> values = #C4;
+  static const field self::E v = #C3;
+  const constructor •(core::int index, core::String name, dynamic _) → self::E
+    : super core::_Enum::•(index, name)
+    ;
+  method toString() → core::String
+    return "E.${this.{core::_Enum::_name}{core::String}}";
+}
+static method main() → dynamic {}
+
+constants  {
+  #C1 = 0
+  #C2 = "v"
+  #C3 = self::E {index:#C1, _name:#C2}
+  #C4 = <self::E*>[#C3]
+}
+
+
+Constructor coverage from constants:
+org-dartlang-testcase:///issue48232.dart:
+- E. (from org-dartlang-testcase:///issue48232.dart:7:9)
+- _Enum. (from org-dartlang-sdk:///sdk/lib/core/enum.dart:103:9)
+- Object. (from org-dartlang-sdk:///sdk/lib/core/object.dart:25:9)

pkg/front_end/testcases/textual_outline.status

@@ -35,6 +35,7 @@ enhanced_enums/inference_in_constructor_parameters: FormatterCrash
 enhanced_enums/instantiated_generic_enum_types: FormatterCrash
 enhanced_enums/issue48084: FormatterCrash
 enhanced_enums/issue48181: FormatterCrash
+enhanced_enums/issue48232: FormatterCrash
 enhanced_enums/malformed_constructors: FormatterCrash
 enhanced_enums/members: FormatterCrash
 enhanced_enums/named_arguments: FormatterCrash