AST: Pass SubstFlags::PreservePackExpansionLevel in a few more places

lib/APIDigester/ModuleAnalyzerNodes.cpp

@@ -1633,7 +1633,9 @@ SwiftDeclCollector::constructTypeNode(Type T, TypeInitInfo Info) {
       ReplaceOpaqueTypesWithUnderlyingTypes replacer(
           /*inContext=*/nullptr, ResilienceExpansion::Maximal,
           /*isWholeModuleContext=*/false);
-      T = T.subst(replacer, replacer, SubstFlags::SubstituteOpaqueArchetypes)
+      T = T.subst(replacer, replacer,
+                  SubstFlags::SubstituteOpaqueArchetypes |
+                  SubstFlags::PreservePackExpansionLevel)
           ->getCanonicalType();
     }
   }

lib/AST/TypeSubstitution.cpp

@@ -1016,7 +1016,9 @@ static Type substOpaqueTypesWithUnderlyingTypesRec(
     llvm::DenseSet<ReplaceOpaqueTypesWithUnderlyingTypes::SeenDecl> &decls) {
   ReplaceOpaqueTypesWithUnderlyingTypes replacer(inContext, contextExpansion,
                                                  isWholeModuleContext, decls);
-  return ty.subst(replacer, replacer, SubstFlags::SubstituteOpaqueArchetypes);
+  return ty.subst(replacer, replacer,
+                  SubstFlags::SubstituteOpaqueArchetypes |
+                  SubstFlags::PreservePackExpansionLevel);
 }
 
 /// Checks that \p dc has access to \p ty for the purposes of an opaque
@@ -1169,7 +1171,8 @@ static ProtocolConformanceRef substOpaqueTypesWithUnderlyingTypesRec(
   ReplaceOpaqueTypesWithUnderlyingTypes replacer(inContext, contextExpansion,
                                                  isWholeModuleContext, decls);
   return ref.subst(origType, replacer, replacer,
-                   SubstFlags::SubstituteOpaqueArchetypes);
+                   SubstFlags::SubstituteOpaqueArchetypes |
+                   SubstFlags::PreservePackExpansionLevel);
 }
 
 ProtocolConformanceRef swift::substOpaqueTypesWithUnderlyingTypes(

lib/SIL/IR/SILFunctionType.cpp

@@ -4800,14 +4800,16 @@ static bool areABICompatibleParamsOrReturns(SILType a, SILType b,
       if (aa.getASTType()->hasOpaqueArchetype())
         opaqueTypesSubstituted = aa.subst(inFunction->getModule(), replacer,
                                          replacer, CanGenericSignature(),
-                                         SubstFlags::SubstituteOpaqueArchetypes);
+                                         SubstFlags::SubstituteOpaqueArchetypes |
+                                         SubstFlags::PreservePackExpansionLevel);
 
       auto opaqueTypesSubstituted2 = bb;
       if (bb.getASTType()->hasOpaqueArchetype())
         opaqueTypesSubstituted2 =
             bb.subst(inFunction->getModule(), replacer, replacer,
                      CanGenericSignature(),
-                     SubstFlags::SubstituteOpaqueArchetypes);
+                     SubstFlags::SubstituteOpaqueArchetypes |
+                     SubstFlags::PreservePackExpansionLevel);
       if (opaqueTypesSubstituted == opaqueTypesSubstituted2)
         continue;
     }