[analyzer] Stop implementing SharedFunctionTypeStructure in analyzer public API.

When I introduced the `SharedFunctionTypeStructure` class in
https://dart-review.googlesource.com/c/sdk/+/386322, I failed to
realize that a side effect of this change was to expose the shared
methods `positionalParameterTypes`,
`requiredPositionalParameterCount`, and `sortedNamedParameters`
through the analyzer's public API.

To correct that mistake, I've moved the reference to
`SharedFunctionTypeStructure` from the `implements` clause of
`FunctionType` to the `implements` clause of `FunctionTypeImpl`.

To avoid this change causing a breakage for clients, I've also added
deprecated declarations of these three getters to the `FunctionType`
class. This ensures that if any analyzer clients have already started
depending on them, their code will continue to work, but they'll be
alerted to the fact that the members will be removed in the future.

This is part of a larger arc of work to change the analyzer's use of
the shared code so that the type parameters it supplies are not part
of the analyzer public API. See
#59763.

Bug: #59763
Change-Id: I442cbe29ed938ec2fed3a3fa65a95c9f0f47a38d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/401921
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Paul Berry <[email protected]>

Author: stereotype441

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

@@ -227,11 +227,7 @@ abstract class DynamicType implements DartType {}
 ///   T<sub>xk</sub> xk}) &rarr; T</i>.
 ///
 /// Clients may not extend, implement or mix-in this class.
-abstract class FunctionType
-    implements
-        DartType,
-        SharedFunctionTypeStructure<DartType, TypeParameterElement,
-            ParameterElement> {
+abstract class FunctionType implements DartType {
   @override
   Null get element;
 
@@ -268,18 +264,45 @@ abstract class FunctionType
   /// in the declaration of the function.
   List<ParameterElement> get parameters;
 
+  /// All the positional parameter types, starting with the required ones, and
+  /// followed by the optional ones.
+  ///
+  /// Deprecated: this getter is a part of the analyzer's private
+  /// implementation, and was exposed by accident (see
+  /// https://github.com/dart-lang/sdk/issues/59763). Please use
+  /// [normalParameterTypes] and [optionalParameterTypes] instead.
+  @Deprecated('Please use normalParameterTypes and optionalParameterTypes')
+  List<DartType> get positionalParameterTypes;
+
+  /// The number of elements of [positionalParameterTypes] that are required
+  /// parameters.
+  ///
+  /// Deprecated: this getter is a part of the analyzer's private
+  /// implementation, and was exposed by accident (see
+  /// https://github.com/dart-lang/sdk/issues/59763). Please use
+  /// [normalParameterTypes].length instead.
+  @Deprecated('Please use normalParameterTypes.length')
+  int get requiredPositionalParameterCount;
+
   /// The type of object returned by this type of function.
-  @override
   DartType get returnType;
 
+  /// All the named parameters, sorted by name.
+  ///
+  /// Deprecated: this getter is a part of the analyzer's private
+  /// implementation, and was exposed by accident (see
+  /// https://github.com/dart-lang/sdk/issues/59763). Please use [parameters]
+  /// instead.
+  @Deprecated('Please use parameters')
+  List<ParameterElement> get sortedNamedParameters;
+
   /// The formal type parameters of this generic function; for example,
   /// `<T> T -> T`.
   //
   // TODO(scheglov): Remove the mention for "typeParameters".
   // These are distinct from the `typeParameters` list, which contains type
   // parameters from surrounding contexts, and thus are free type variables
   // from the perspective of this function type.
-  @override
   List<TypeParameterElement> get typeFormals;
 
   /// The type parameters.

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

@@ -86,7 +86,11 @@ class DynamicTypeImpl extends TypeImpl
 }
 
 /// The type of a function, method, constructor, getter, or setter.
-class FunctionTypeImpl extends TypeImpl implements FunctionType {
+class FunctionTypeImpl extends TypeImpl
+    implements
+        FunctionType,
+        SharedFunctionTypeStructure<DartType, TypeParameterElement,
+            ParameterElement> {
   @override
   late int hashCode = _computeHashCode();
 

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

@@ -24,6 +24,7 @@ import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/src/dart/ast/ast.dart';
 import 'package:analyzer/src/dart/element/element.dart';
+import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/type_algebra.dart';
 import 'package:analyzer/src/dart/element/type_schema.dart';
 import 'package:analyzer/src/dart/resolver/flow_analysis_visitor.dart';
@@ -226,7 +227,7 @@ class TypeConstraintGatherer extends shared.TypeConstraintGenerator<
   @override
   (DartType, DartType, {List<TypeParameterElement> typeParametersToEliminate})
       instantiateFunctionTypesAndProvideFreshTypeParameters(
-          covariant FunctionType P, covariant FunctionType Q,
+          covariant FunctionTypeImpl P, covariant FunctionTypeImpl Q,
           {required bool leftSchema}) {
     // And `Z0...Zn` are fresh variables with bounds `B20, ..., B2n`.
     //   Where `B2i` is `B0i[Z0/T0, ..., Zn/Tn]` if `P` is a type schema.