On Tue, Feb 05, 2019 at 04:17:48PM -0500, Jason Merrill wrote: > On 2/5/19 3:43 PM, Marek Polacek wrote: > > On Tue, Feb 05, 2019 at 01:24:15PM -0500, Jason Merrill wrote: > > > On 2/5/19 11:31 AM, Jakub Jelinek wrote: > > > > On Tue, Feb 05, 2019 at 11:24:14AM -0500, Jason Merrill wrote: > > > > > Yes, thanks, mark_rvalue_use is definitely wrong here. But > > > > > mark_lvalue_use > > > > > might be wrong as well; we don't know here how the expression is used > > > > > by the > > > > > inner conversions for the user-defined conversion. Can we remove the > > > > > call > > > > > entirely? It doesn't seem to break any Wunused* tests. > > > > > > > > It was added in r159096 for -Wunused-but-set*. It is surely possible > > > > it is > > > > now covered by other mark_*_use calls. Or could we call there just > > > > mark_exp_read instead? > > > > > > That would be fine too. > > > > So how about this if it passes testing? > > > > Bootstrapped/regtested running on x86_64-linux, ok for trunk/8? > > > > 2019-02-05 Marek Polacek <pola...@redhat.com> > > > > PR c++/89158 - by-value capture of constexpr variable broken. > > * call.c (convert_like_real) <case ck_user>: Call mark_exp_read > > instead of mark_rvalue_use. > > > > * g++.dg/cpp0x/lambda/lambda-89158.C: New test. > > > > diff --git gcc/cp/call.c gcc/cp/call.c > > index c74d1b4ebdf..020a095dade 100644 > > --- gcc/cp/call.c > > +++ gcc/cp/call.c > > @@ -7006,7 +7006,9 @@ convert_like_real (conversion *convs, tree expr, tree > > fn, int argnum, > > return expr; > > } > > - expr = mark_rvalue_use (expr); > > + /* Calling mark_rvalue_use could turn a decl into a constant, breaking > > + e.g. the need_temporary_p assumption in the ICS. */ > > + mark_exp_read (expr); > > I'd describe the issue at a higher level, e.g. "we don't know here whether > expr is being used as an lvalue or rvalue". mark_rvalue_use is wrong for > this testcase because expr is actually used as an lvalue. OK with that > change.
Will do, thanks! Marek
