[IRGen] fix createCXXCopyConstructorFunctionType

The previous implementation assumes `UnsafePointer` has no requirements
on its generic parameter. This fix handles any requirements that may be
present on the parameter. With NoncopyableGenerics, the generic
parameter actually does gain a requirement.

Author: kavon

lib/IRGen/GenStruct.cpp

@@ -589,9 +589,18 @@ namespace {
       //   void (%struct.T* %this, %struct.T* %0)
       auto ptrTypeDecl =
           IGF.getSILModule().getASTContext().getUnsafePointerDecl();
-      auto subst = SubstitutionMap::get(ptrTypeDecl->getGenericSignature(),
-                                        {T.getASTType()},
-                                        ArrayRef<ProtocolConformanceRef>{});
+      auto sig = ptrTypeDecl->getGenericSignature();
+
+      // Map the generic parameter to T
+      auto params = sig.getGenericParams();
+      assert(params.size() == 1);
+      auto param = params[0]->getCanonicalType()->castTo<SubstitutableType>();
+      TypeSubstitutionMap map;
+      map[param] = T.getASTType();
+
+      auto subst = SubstitutionMap::get(sig,
+                              QueryTypeSubstitutionMap{map},
+                              LookUpConformanceInModule{IGF.getSwiftModule()});
       auto ptrType = ptrTypeDecl->getDeclaredInterfaceType().subst(subst);
       SILParameterInfo ptrParam(ptrType->getCanonicalType(),
                                 ParameterConvention::Direct_Unowned);