https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66146
Thomas Schwinge <tschwinge at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |tschwinge at gcc dot gnu.org
--- Comment #35 from Thomas Schwinge <tschwinge at gcc dot gnu.org> ---
In an '--enable-werror' configuration (assuming that's relevant), I'm seeing
new code from commit r11-4691-g93e79ed391b9c636f087e6eb7e70f14963cd10ad
"libstdc++: Rewrite std::call_once to use futexes [PR 66146]" fail to build:
[...]/source-gcc/libstdc++-v3/src/c++11/mutex.cc: In member function ‘void
std::once_flag::_M_finish(bool)’:
[...]/source-gcc/libstdc++-v3/src/c++11/mutex.cc:77:11: error: unused
variable ‘prev’ [-Werror=unused-variable]
77 | int prev = __atomic_exchange_n(&_M_once, newval,
__ATOMIC_RELEASE);
| ^~~~
cc1plus: all warnings being treated as errors
Makefile:648: recipe for target 'mutex.lo' failed
make[5]: *** [mutex.lo] Error 1
make[5]: Leaving directory
'[...]/build-gcc/x86_64-pc-linux-gnu/libstdc++-v3/src/c++11'
Should a '(void) prev;' be added (my current workaround), or 'prev' get some
attribute 'used' added, or something else?
