Elements. Deprecate TypeParameterElement.

Change-Id: I2f4c22fb4928cb5f296a190d7c165a3887d9eeae
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/418833
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Paul Berry <paulberry@google.com>

pkg/analyzer/api.txt

@@ -3454,7 +3454,7 @@ package:analyzer/dart/element/element.dart:
     name (getter: String)
     parameterKind (getter: ParameterKind, deprecated)
     parameters (getter: List<ParameterElement>)
-    typeParameters (getter: List<TypeParameterElement>)
+    typeParameters (getter: List<TypeParameterElement>, deprecated)
     appendToWithoutDelimiters (method: void Function(StringBuffer, {bool withNullability}))
   PartElement (class extends Object implements _ExistingElement):
     new (constructor: PartElement Function())
@@ -3509,7 +3509,7 @@ package:analyzer/dart/element/element.dart:
     instantiate (method: DartType Function({required NullabilitySuffix nullabilitySuffix, required List<DartType> typeArguments}))
   TypeDefiningElement (class extends Object implements Element):
     new (constructor: TypeDefiningElement Function())
-  TypeParameterElement (class extends Object implements TypeDefiningElement):
+  TypeParameterElement (class extends Object implements TypeDefiningElement, deprecated):
     new (constructor: TypeParameterElement Function())
     bound (getter: DartType?)
     declaration (getter: TypeParameterElement)
@@ -3519,7 +3519,7 @@ package:analyzer/dart/element/element.dart:
   TypeParameterizedElement (class extends Object implements _ExistingElement):
     new (constructor: TypeParameterizedElement Function())
     isSimplyBounded (getter: bool)
-    typeParameters (getter: List<TypeParameterElement>)
+    typeParameters (getter: List<TypeParameterElement>, deprecated)
   UndefinedElement (class extends Object implements Element):
     new (constructor: UndefinedElement Function())
   UriReferencedElement (class extends Object implements _ExistingElement):

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

@@ -1984,6 +1984,7 @@ abstract class ParameterElement
   ///
   /// A parameter will only define type parameters if it is a function typed
   /// parameter.
+  @Deprecated(elementModelDeprecationMsg)
   List<TypeParameterElement> get typeParameters;
 
   /// Appends the type, name and possibly the default value of this parameter
@@ -2239,6 +2240,7 @@ abstract class TypeDefiningElement implements Element {}
 /// A type parameter.
 ///
 /// Clients may not extend, implement or mix-in this class.
+@Deprecated('Use TypeParameterElement2 instead')
 abstract class TypeParameterElement implements TypeDefiningElement {
   /// The type representing the bound associated with this parameter, or `null`
   /// if this parameter does not have an explicit bound. Being able to
@@ -2278,6 +2280,7 @@ abstract class TypeParameterizedElement implements _ExistingElement {
   ///
   /// This does not include type parameters that are declared by any enclosing
   /// elements.
+  @Deprecated(elementModelDeprecationMsg)
   List<TypeParameterElement> get typeParameters;
 }
 

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

@@ -3298,7 +3298,7 @@ abstract class ElementImpl2 implements Element2 {
   /// The reference of this element, used during reading summaries.
   ///
   /// Can be `null` if this element cannot be referenced from outside,
-  /// for example a [LocalFunctionElement], a [TypeParameterElement],
+  /// for example a [LocalFunctionElement], a [TypeParameterElement2],
   /// a positional [FormalParameterElement], etc.
   Reference? get reference => null;
 
@@ -11343,9 +11343,11 @@ class TypeAliasElementImpl2 extends TypeDefiningElementImpl2
 abstract class TypeDefiningElementImpl2 extends ElementImpl2
     implements TypeDefiningElement2 {}
 
-/// A concrete implementation of a [TypeParameterElement].
 class TypeParameterElementImpl extends ElementImpl
-    implements TypeParameterElement, TypeParameterFragment {
+    implements
+        // ignore:deprecated_member_use_from_same_package
+        TypeParameterElement,
+        TypeParameterFragment {
   @override
   String? name2;
 

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

@@ -702,10 +702,6 @@ extension TypeAliasElementImplExtension on TypeAliasElementImpl {
 }
 
 extension TypeParameterElement2Extension on TypeParameterElement2 {
-  TypeParameterElement get asElement {
-    return firstFragment as TypeParameterElement;
-  }
-
   TypeParameterElementImpl2 freshCopy() {
     var fragment = TypeParameterElementImpl(
       name3 ?? '',
@@ -719,12 +715,6 @@ extension TypeParameterElement2Extension on TypeParameterElement2 {
   }
 }
 
-extension TypeParameterElementExtension on TypeParameterElement {
-  TypeParameterElement2 get asElement2 {
-    return (this as TypeParameterElementImpl).asElement2;
-  }
-}
-
 extension TypeParameterElementImpl2Extension on TypeParameterElementImpl2 {
   TypeParameterElementImpl get asElement {
     return firstFragment;