Augment. Allow 'static abstract' fields.

Change-Id: I42c4bbb9193c2debd3661898a8c410f76916958a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/504720
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

pkg/analysis_server/test/src/services/correction/fix/remove_lexeme_test.dart

@@ -227,17 +227,20 @@ class RemoveLexemeTest extends FixProcessorTest {
 
   Future<void> test_abstract_static_field() async {
     await resolveTestCode('''
+// @dart = 3.5
 abstract class A {
   abstract static int? i;
 }
 ''');
     await assertHasFix('''
+// @dart = 3.5
 abstract class A {
   static int? i;
 }
 ''');
   }
 
+  @FailingTest(reason: 'The code snippet and test name do not match')
   Future<void> test_abstract_static_method() async {
     await resolveTestCode('''
 abstract class A {

pkg/analyzer/lib/src/fasta/ast_builder.dart

@@ -6046,7 +6046,7 @@ class AstBuilder extends StackListener {
     assert(optional(';', endToken));
 
     if (abstractToken != null) {
-      if (staticToken != null) {
+      if (staticToken != null && !enableAugmentations) {
         handleRecoverableError(
           fe_diag.abstractStaticField,
           abstractToken,

pkg/analyzer/test/generated/class_member_parser_test.dart

@@ -3052,29 +3052,6 @@ FieldDeclaration
 ''');
   }
 
-  void test_parseField_abstract_static() {
-    var parseResult = parseStringWithErrors(r'''
-class C {
-  abstract static int? i;
-}
-''');
-    parseResult.assertErrors([error(diag.abstractStaticField, 12, 8)]);
-    var node = parseResult.findNode.singleClassMember;
-    assertParsedNodeText(node, r'''
-FieldDeclaration
-  staticKeyword: static
-  abstractKeyword: abstract
-  fields: VariableDeclarationList
-    type: NamedType
-      name: int
-      question: ?
-    variables
-      VariableDeclaration
-        name: i
-  semicolon: ;
-''');
-  }
-
   void test_parseField_const_late() {
     var parseResult = parseStringWithErrors(r'''
 class C {

pkg/analyzer/test/src/dart/parser/class_test.dart

@@ -1407,6 +1407,69 @@ ClassDeclaration
 ''');
   }
 
+  test_field_static_abstract() {
+    var parseResult = parseStringWithErrors(r'''
+class A {
+  static abstract int? foo;
+}
+''');
+    parseResult.assertExpectedDiagnostics();
+    assertParsedNodeText(parseResult.findNode.singleClassDeclaration, r'''
+ClassDeclaration
+  classKeyword: class
+  namePart: NameWithTypeParameters
+    typeName: A
+  body: BlockClassBody
+    leftBracket: {
+    members
+      FieldDeclaration
+        staticKeyword: static
+        abstractKeyword: abstract
+        fields: VariableDeclarationList
+          type: NamedType
+            name: int
+            question: ?
+          variables
+            VariableDeclaration
+              name: foo
+        semicolon: ;
+    rightBracket: }
+''');
+  }
+
+  test_field_static_abstract_language305() {
+    var parseResult = parseStringWithErrors(r'''
+// @dart = 3.5
+class A {
+  static abstract int? foo;
+//       ^^^^^^^^
+// [diag.abstractStaticField] Static fields can't be declared 'abstract'.
+}
+''');
+    parseResult.assertExpectedDiagnostics();
+    assertParsedNodeText(parseResult.findNode.singleClassDeclaration, r'''
+ClassDeclaration
+  classKeyword: class
+  namePart: NameWithTypeParameters
+    typeName: A
+  body: BlockClassBody
+    leftBracket: {
+    members
+      FieldDeclaration
+        staticKeyword: static
+        abstractKeyword: abstract
+        fields: VariableDeclarationList
+          type: NamedType
+            name: int
+            question: ?
+          variables
+            VariableDeclaration
+              name: foo
+        semicolon: ;
+    rightBracket: }
+''');
+  }
+
   test_getter_augment() {
     var parseResult = parseStringWithErrors(r'''
 augment class A {