https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65455
--- Comment #11 from Jens Gustedt <jens.gustedt at inria dot fr> --- (In reply to jos...@codesourcery.com from comment #10) > On Wed, 18 Mar 2015, jens.gustedt at inria dot fr wrote: > > > (Perhaps gcc interprets _Generic as you say, but even the standard committee > > doesn't agree on that interpretation, and other compiler implementors don't > > agree either. Nothing in the standard says that it is an rvalue, nor that it > > has to undergo any conversion. Conversion for non-evaluated expressions > > simply > > doesn't exist in the standard. The standard explicitly asks for compatible > > type > > of the expression itself, it says nothing about unqualified type.) > > There isn't yet a conclusion to DR#423, but the committee discussion in > N1892 says 'Specifically, the controlling expression of a generic > selection "was very carefully not added" to the list of cases where lvalue > conversion is not done.' (i.e. that conversion happens to all expressions > unless excluded from happening). There is no indication of a committee > direction contradicting the approach I chose for GCC (even if the > committee isn't quite sure of how to handle atomics there, and has > suggested making qualifiers on function return types not part of the > type). And now we are exactly in the situation that I was afraid of happening, compiler implementors interpret _Generic differently. Your interpretation and the one that clang applies differ and make it that code with _Generic isn't portable. That is just a disaster for an early (well not so early anymore) adoption of C11.
