AST: Use new form of getOpenedExistentialSignature() in getMinimalCanonicalType()

Author: slavapestov

include/swift/AST/Types.h

@@ -587,7 +587,7 @@ class alignas(1 << TypeAlignInBits) TypeBase
   /// Canonical protocol composition types are minimized only to a certain
   /// degree to preserve ABI compatibility. This routine enables performing
   /// slower, but stricter minimization at need (e.g. redeclaration checking).
-  CanType getMinimalCanonicalType(const DeclContext *useDC) const;
+  CanType getMinimalCanonicalType() const;
 
   /// Reconstitute type sugar, e.g., for array types, dictionary
   /// types, optionals, etc.
@@ -6139,7 +6139,7 @@ class ProtocolCompositionType final : public TypeBase,
   /// Canonical protocol composition types are minimized only to a certain
   /// degree to preserve ABI compatibility. This routine enables performing
   /// slower, but stricter minimization at need (e.g. redeclaration checking).
-  CanType getMinimalCanonicalType(const DeclContext *useDC) const;
+  CanType getMinimalCanonicalType() const;
 
   /// Retrieve the set of members composed to create this type.
   ///

lib/AST/Decl.cpp

@@ -3636,7 +3636,7 @@ CanType ValueDecl::getOverloadSignatureType() const {
                                     /*topLevelFunction=*/true, isMethod,
                                     /*isInitializer=*/isa<ConstructorDecl>(afd),
                                     getNumCurryLevels())
-        ->getMinimalCanonicalType(afd);
+        ->getMinimalCanonicalType();
   }
 
   if (isa<AbstractStorageDecl>(this)) {
@@ -3652,7 +3652,7 @@ CanType ValueDecl::getOverloadSignatureType() const {
                                    /*topLevelFunction=*/true,
                                    /*isMethod=*/false,
                                    /*isInitializer=*/false, getNumCurryLevels())
-              ->getMinimalCanonicalType(cast<SubscriptDecl>(this));
+              ->getMinimalCanonicalType();
     }
 
     // We want to curry the default signature type with the 'self' type of the
@@ -3667,7 +3667,7 @@ CanType ValueDecl::getOverloadSignatureType() const {
     auto mappedType = mapSignatureFunctionType(
         getASTContext(), getInterfaceType(), /*topLevelFunction=*/false,
         /*isMethod=*/false, /*isInitializer=*/false, getNumCurryLevels());
-    return mappedType->getMinimalCanonicalType(getDeclContext());
+    return mappedType->getMinimalCanonicalType();
   }
 
   // Note: If you add more cases to this function, you should update the

lib/AST/Type.cpp

@@ -1836,8 +1836,9 @@ CanType TypeBase::getReducedType(GenericSignature sig) {
   return sig.getReducedType(this);
 }
 
-CanType TypeBase::getMinimalCanonicalType(const DeclContext *useDC) const {
-  const auto MinimalTy = getCanonicalType().transformRec([useDC](TypeBase *Ty) -> std::optional<Type> {
+CanType TypeBase::getMinimalCanonicalType() const {
+  const auto MinimalTy = getCanonicalType().transformRec(
+      [](TypeBase *Ty) -> std::optional<Type> {
     const CanType CanTy = CanType(Ty);
 
     if (const auto ET = dyn_cast<ExistentialType>(CanTy)) {
@@ -1847,7 +1848,7 @@ CanType TypeBase::getMinimalCanonicalType(const DeclContext *useDC) const {
         return CanTy;
       }
 
-      const auto MinimalTy = PCT->getMinimalCanonicalType(useDC);
+      const auto MinimalTy = PCT->getMinimalCanonicalType();
       if (MinimalTy->getClassOrBoundGenericClass()) {
         return MinimalTy;
       }
@@ -1861,7 +1862,7 @@ CanType TypeBase::getMinimalCanonicalType(const DeclContext *useDC) const {
         return CanTy;
       }
 
-      const auto MinimalTy = PCT->getMinimalCanonicalType(useDC);
+      const auto MinimalTy = PCT->getMinimalCanonicalType();
       if (MinimalTy->getClassOrBoundGenericClass()) {
         return MetatypeType::get(MinimalTy);
       }
@@ -1870,7 +1871,7 @@ CanType TypeBase::getMinimalCanonicalType(const DeclContext *useDC) const {
     }
 
     if (const auto Composition = dyn_cast<ProtocolCompositionType>(CanTy)) {
-      return Composition->getMinimalCanonicalType(useDC);
+      return Composition->getMinimalCanonicalType();
     }
 
     return std::nullopt;
@@ -3795,21 +3796,15 @@ Type ProtocolCompositionType::get(const ASTContext &C,
   return build(C, CanTypes, Inverses, HasExplicitAnyObject);
 }
 
-CanType ProtocolCompositionType::getMinimalCanonicalType(
-    const DeclContext *useDC) const {
+CanType ProtocolCompositionType::getMinimalCanonicalType() const {
   auto &Ctx = getASTContext();
 
-  // Use generic signature minimization: the requirements of the signature will
-  // represent the minimal composition.
-  auto parentSig = useDC->getGenericSignatureOfContext();
-  auto existentialSig =
-      Ctx.getOpenedExistentialSignature(getCanonicalType(), parentSig);
-  auto selfTy =
-      OpenedArchetypeType::getSelfInterfaceTypeFromContext(parentSig, Ctx);
-  return existentialSig->getUpperBound(selfTy,
-                                       /*forExistentialSelf=*/true,
-                                       /*includeParameterizedProtocols=*/true)
-            ->getCanonicalType();
+  auto existentialSig = Ctx.getOpenedExistentialSignature(getCanonicalType());
+  auto result = existentialSig.OpenedSig->getUpperBound(
+      existentialSig.SelfType,
+      /*forExistentialSelf=*/true,
+      /*includeParameterizedProtocols=*/true);
+  return result.subst(existentialSig.Generalization)->getCanonicalType();
 }
 
 ClangTypeInfo AnyFunctionType::getClangTypeInfo() const {