Merge pull request swiftlang#76445 from slavapestov/maptypeintocontext

Overhaul mapTypeIntoContext()

Author: slavapestov

include/swift/AST/GenericEnvironment.h

@@ -157,16 +157,14 @@ class alignas(1 << DeclAlignInBits) GenericEnvironment final
   friend ArchetypeType;
   friend QueryInterfaceTypeSubstitutions;
 
-  Type getOrCreateArchetypeFromInterfaceType(Type depType);
-
-  /// Add a mapping of a generic parameter to a specific type (which may be
-  /// an archetype)
-  void addMapping(GenericParamKey key, Type contextType);
+  /// Add a mapping of a type parameter to a contextual type, usually
+  /// an archetype.
+  void addMapping(CanType depType, Type contextType);
 
-  /// Retrieve the mapping for the given generic parameter, if present.
+  /// Retrieve the mapping for the given type parameter, if present.
   ///
   /// This is only useful when lazily populating a generic environment.
-  std::optional<Type> getMappingIfPresent(GenericParamKey key) const;
+  Type getMappingIfPresent(CanType depType) const;
 
 public:
   GenericSignature getGenericSignature() const {
@@ -283,13 +281,12 @@ class alignas(1 << DeclAlignInBits) GenericEnvironment final
   /// Map an interface type to a contextual type.
   Type mapTypeIntoContext(Type type) const;
 
-  /// Map an interface type to a contextual type.
-  Type mapTypeIntoContext(Type type,
-                          LookupConformanceFn lookupConformance) const;
-
   /// Map a generic parameter type to a contextual type.
   Type mapTypeIntoContext(GenericTypeParamType *type) const;
 
+  /// Map a type parameter type to a contextual type.
+  Type getOrCreateArchetypeFromInterfaceType(Type depType);
+
   /// Map an interface type containing parameter packs to a contextual
   /// type in the opened element generic context.
   Type mapPackTypeIntoElementContext(Type type) const;

include/swift/AST/GenericSignature.h

@@ -170,9 +170,6 @@ class GenericSignature {
   /// Stores a set of requirements on a type parameter. Used by
   /// GenericEnvironment for building archetypes.
   struct LocalRequirements {
-    Type anchor;
-
-    Type concreteType;
     Type superclass;
 
     RequiredProtocols protos;
@@ -407,6 +404,11 @@ class alignas(1 << TypeAlignInBits) GenericSignatureImpl final
 
   bool isReducedType(Type type) const;
 
+  /// Return the reduced version of the given type parameter under this generic
+  /// signature. To reduce a type that more generally contains type parameters,
+  /// use GenericSignature::getReducedType().
+  CanType getReducedTypeParameter(CanType type) const;
+
   /// Determine whether the given type parameter is defined under this generic
   /// signature.
   bool isValidTypeParameter(Type type) const;

include/swift/AST/Types.h

@@ -6588,11 +6588,7 @@ class ArchetypeType : public SubstitutableType,
   bool requiresClass() const;
 
   /// Retrieve the superclass of this type, if such a requirement exists.
-  Type getSuperclass() const {
-    if (!Bits.ArchetypeType.HasSuperclass) return Type();
-
-    return *getSubclassTrailingObjects<Type>();
-  }
+  Type getSuperclass() const;
 
   /// Retrieve the layout constraint of this type, if such a requirement exists.
   LayoutConstraint getLayoutConstraint() const {