Legacy. Deprecate LibraryElement.toLegacyElementIfOptOut

Change-Id: I2dceca5c2f0a5771a8f6aff79db3e32a7fa8993c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/349984
Reviewed-by: Phil Quitslund <pquitslund@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

pkg/analyzer/CHANGELOG.md

@@ -1,5 +1,6 @@
 ## 6.5.0-dev
 * Deprecated `LibraryElement.toLegacyTypeIfOptOut`.
+* Deprecated `LibraryElement.toLegacyElementIfOptOut`.
 
 ## 6.4.1
 * Patch for crash in ffi_verifier.

pkg/analyzer/lib/dart/element/element.dart

@@ -1875,6 +1875,7 @@ abstract class LibraryElement
   /// If a legacy library, returns the legacy view on the [element].
   ///
   /// Otherwise, return the original element.
+  @Deprecated('Only non-nullable by default mode is supported')
   T toLegacyElementIfOptOut<T extends Element>(T element);
 
   /// If a legacy library, return the legacy version of the [type].

pkg/analyzer/lib/src/dart/element/element.dart

@@ -4516,10 +4516,10 @@ class LibraryElementImpl extends LibraryOrAugmentationElementImpl
     );
   }
 
+  @Deprecated('Only non-nullable by default mode is supported')
   @override
   T toLegacyElementIfOptOut<T extends Element>(T element) {
-    if (isNonNullableByDefault) return element;
-    return Member.legacy(element) as T;
+    return element;
   }
 
   @Deprecated('Only non-nullable by default mode is supported')

pkg/analyzer/lib/src/error/correct_override.dart

@@ -9,7 +9,6 @@ import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/src/dart/analysis/session.dart';
-import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/dart/element/extensions.dart';
 import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/type_algebra.dart';
@@ -18,7 +17,6 @@ import 'package:analyzer/src/diagnostic/diagnostic_factory.dart';
 import 'package:analyzer/src/error/codes.dart';
 
 class CorrectOverrideHelper {
-  final LibraryElementImpl _library;
   final TypeSystemImpl _typeSystem;
 
   final ExecutableElement _thisMember;
@@ -27,10 +25,9 @@ class CorrectOverrideHelper {
   final DiagnosticFactory _diagnosticFactory = DiagnosticFactory();
 
   CorrectOverrideHelper({
-    required LibraryElementImpl library,
+    required TypeSystemImpl typeSystem,
     required ExecutableElement thisMember,
-  })  : _library = library,
-        _typeSystem = library.typeSystem,
+  })  : _typeSystem = typeSystem,
         _thisMember = thisMember {
     _computeThisTypeForSubtype();
   }
@@ -39,8 +36,6 @@ class CorrectOverrideHelper {
   bool isCorrectOverrideOf({
     required ExecutableElement superMember,
   }) {
-    superMember = _library.toLegacyElementIfOptOut(superMember);
-
     var superType = superMember.type;
     return _typeSystem.isSubtypeOf(_thisTypeForSubtype!, superType);
   }

pkg/analyzer/lib/src/error/inheritance_override.dart

@@ -319,9 +319,8 @@ class _ClassVerifier {
         //  diagnostic should be reported on the name of the mixin defining the
         //  method. In other cases, it should be reported on the name of the
         //  overriding method. The classNameNode is always wrong.
-        concreteElement = library.toLegacyElementIfOptOut(concreteElement);
         CorrectOverrideHelper(
-          library: library,
+          typeSystem: typeSystem,
           thisMember: concreteElement,
         ).verify(
           superMember: interfaceElement,
@@ -355,7 +354,7 @@ class _ClassVerifier {
 
     var name = Name(libraryUri, member.name);
     var correctOverrideHelper = CorrectOverrideHelper(
-      library: library,
+      typeSystem: typeSystem,
       thisMember: member,
     );
 

pkg/analyzer/lib/src/generated/error_verifier.dart

@@ -4057,7 +4057,7 @@ class ErrorVerifier extends RecursiveAstVisitor<void>
 
       if (mixinMember != null) {
         var isCorrect = CorrectOverrideHelper(
-          library: _currentLibrary,
+          typeSystem: typeSystem,
           thisMember: superMember,
         ).isCorrectOverrideOf(
           superMember: mixinMember,
@@ -4239,9 +4239,6 @@ class ErrorVerifier extends RecursiveAstVisitor<void>
     final superElement = superType.element;
     // try to find default generative super constructor
     var superUnnamedConstructor = superElement.unnamedConstructor;
-    superUnnamedConstructor = superUnnamedConstructor != null
-        ? _currentLibrary.toLegacyElementIfOptOut(superUnnamedConstructor)
-        : superUnnamedConstructor;
     if (superUnnamedConstructor != null) {
       if (superUnnamedConstructor.isFactory) {
         errorReporter.reportErrorForElement(
@@ -5073,9 +5070,6 @@ class ErrorVerifier extends RecursiveAstVisitor<void>
     }
 
     var superUnnamedConstructor = superElement.unnamedConstructor;
-    superUnnamedConstructor = superUnnamedConstructor != null
-        ? _currentLibrary.toLegacyElementIfOptOut(superUnnamedConstructor)
-        : superUnnamedConstructor;
     if (superUnnamedConstructor == null) {
       errorReporter.atNode(
         constructor.returnType,