AST/Sema: Use ProtocolConformanceRef::getTypeWitness()

Author: slavapestov

Diff for: lib/AST/ProtocolConformanceRef.cpp

@@ -163,8 +163,7 @@ ProtocolConformanceRef::getTypeWitnessByName(Type type, Identifier name) const {
   if (!assocType)
     return ErrorType::get(proto->getASTContext());
 
-  return assocType->getDeclaredInterfaceType().subst(
-    SubstitutionMap::getProtocolSubstitutions(proto, type, *this));
+  return getTypeWitness(type, assocType);
 }
 
 ConcreteDeclRef

Diff for: lib/AST/RequirementMachine/ConcreteContraction.cpp

@@ -302,8 +302,7 @@ ConcreteContraction::substTypeParameterRec(Type type, Position position) const {
         return std::nullopt;
       }
 
-      return conformance.getAssociatedType(
-          *substBaseType, assocType->getDeclaredInterfaceType());
+      return conformance.getTypeWitness(*substBaseType, assocType);
     }
 
     // An unresolved DependentMemberType stores an identifier. Handle this

Diff for: lib/AST/RequirementMachine/GenericSignatureQueries.cpp

@@ -346,9 +346,7 @@ static Type substPrefixType(Type type, unsigned suffixLength, Type prefixType,
   auto *assocDecl = memberType->getAssocType();
   auto *proto = assocDecl->getProtocol();
   auto conformance = lookupConformance(substBaseType, proto);
-  return conformance.getAssociatedType(
-      substBaseType,
-      assocDecl->getDeclaredInterfaceType());
+  return conformance.getTypeWitness(substBaseType, assocDecl);
 }
 
 Type RequirementMachine::getReducedTypeParameter(

Diff for: lib/AST/RequirementMachine/RequirementLowering.cpp

@@ -665,8 +665,7 @@ struct InferRequirementsWalker : public TypeWalker {
         auto addSameTypeConstraint = [&](Type firstType,
                                          AssociatedTypeDecl *assocType) {
           auto conformance = lookupConformance(firstType, differentiableProtocol);
-          auto secondType = conformance.getAssociatedType(
-              firstType, assocType->getDeclaredInterfaceType());
+          auto secondType = conformance.getTypeWitness(firstType, assocType);
           reqs.push_back({Requirement(RequirementKind::SameType,
                                       firstType, secondType),
                           SourceLoc()});

Diff for: lib/AST/Type.cpp

@@ -4467,8 +4467,7 @@ TypeBase::getAutoDiffTangentSpace(LookupConformanceFn lookupConformance) {
   // Try to get the `TangentVector` associated type of `base`.
   // Return the associated type if it is valid.
   auto conformance = swift::lookupConformance(this, differentiableProtocol);
-  auto assocTy = conformance.getAssociatedType(
-      this, assocDecl->getDeclaredInterfaceType());
+  auto assocTy = conformance.getTypeWitness(this, assocDecl);
   if (!assocTy->hasError())
     return cache(TangentSpace::getTangentVector(assocTy));
 

Diff for: lib/Sema/ConstraintSystem.cpp

@@ -4165,8 +4165,7 @@ struct TypeSimplifier {
           return memberTy;
         }
 
-        auto result = conformance.getAssociatedType(
-            lookupBaseType, assocType->getDeclaredInterfaceType());
+        auto result = conformance.getTypeWitness(lookupBaseType, assocType);
         if (result && !result->hasError())
           return result;
       }

Diff for: lib/Sema/TypeCheckEffects.cpp

@@ -1167,8 +1167,8 @@ class ApplyClassifier {
           conditional = ConditionalEffectKind::Always;
 
         // Use the Failure type witness, when present.
-        Type thrownError = conformanceRef.getAssociatedType(
-            type, failureAssocType->getDeclaredInterfaceType());
+        Type thrownError = conformanceRef.getTypeWitness(
+            type, failureAssocType);
         return Classification::forThrows(
             thrownError, conditional,
             /*FIXME*/PotentialEffectReason::forConformance());