On Fri, Jan 20, 2017 at 8:15 AM, Nathan Sidwell <nat...@acm.org> wrote: > Bug 78495 is a wrong code bug caused by an invisiref parm. When building > the inherited ctor, we use forward_parm to create a forwarding reference. > That code generation considers the type of the parm to be 'T'. We thus end > up with a tree that looks like *&PARM > > The subsequent call gets 'CALL_FROM_THUNK' set. We need that set so code > generation doesn't copy pass-by-invisiref objects that are specified by the > C abi (but not specified so by the C++ abi) (POD structs, commonly). > > cp_genericize is used to mutate invisiref parm_decls from T to &T and bash > their uses from PARM to *PARM (with suitable checking of &PARM turning into > plain PARM). However it explicitly skips genericizing the args of a > CALL_FROM_THUNK tree. Thus we end up taking the address of the reference > parm itself. > > That appears to be incorrect now we have forward_parm. This patch deletes > that skipping.
Hmm, I would guess that if we're going to do this we need to also use forward_parm in maybe_thunk_body. Jason
