[Sema] Allow implicit parameter decls to have property wrapper attributes

Author: xedin

lib/AST/Decl.cpp

@@ -6733,7 +6733,8 @@ bool VarDecl::hasStorageOrWrapsStorage() const {
 }
 
 void VarDecl::visitAuxiliaryDecls(llvm::function_ref<void(VarDecl *)> visit) const {
-  if (getDeclContext()->isTypeContext() || isImplicit())
+  if (getDeclContext()->isTypeContext() ||
+      (isImplicit() && !isa<ParamDecl>(this)))
     return;
 
   if (getAttrs().hasAttribute<LazyAttr>()) {

lib/Sema/TypeCheckStorage.cpp

@@ -2981,7 +2981,8 @@ PropertyWrapperAuxiliaryVariablesRequest::evaluate(Evaluator &evaluator,
 PropertyWrapperInitializerInfo
 PropertyWrapperInitializerInfoRequest::evaluate(Evaluator &evaluator,
                                                 VarDecl *var) const {
-  if (!var->hasAttachedPropertyWrapper() || var->isImplicit())
+  if (!var->hasAttachedPropertyWrapper() ||
+      (var->isImplicit() && !isa<ParamDecl>(var)))
     return PropertyWrapperInitializerInfo();
 
   auto wrapperInfo = var->getAttachedPropertyWrapperTypeInfo(0);