[Bug c++/59800] Compilation with g++ fails when -Ofast -flto is used to compile code using some <random> distribution

["manu at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59800

Manuel LÃpez-IbÃÃez <manu at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |NEW
                 CC|                            |manu at gcc dot gnu.org

--- Comment #4 from Manuel LÃpez-IbÃÃez <manu at gcc dot gnu.org> ---
The meaning is explained here: https://gcc.gnu.org/bugs/management.html
but I think it was a slip in this case.

Probably the uninit pass is not powerful enough, but in this case the warning
should be suppressed for system-headers:

manuel@gcc10:~$ ~/test1/210581/install/bin/g++ -std=c++11  -O2 -Wsystem-headers
-Wmaybe-uninitialized test.cc
In file included from
/home/manuel/test1/210581/install/include/c++/4.10.0/random:51:0,
                 from test.cc:3:
/home/manuel/test1/210581/install/include/c++/4.10.0/bits/random.tcc: In
function âint main(int, char**)â:
/home/manuel/test1/210581/install/include/c++/4.10.0/bits/random.tcc:1964:2:
warning: â*((void*)(&
my_lognormal)+16).std::normal_distribution<double>::_M_savedâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
  __ret = __ret * __param.stddev() + __param.mean();
  ^
test.cc:11:33: note: â*((void*)(&
my_lognormal)+16).std::normal_distribution<double>::_M_savedâ was declared here
  lognormal_distribution<double> my_lognormal(0.0, 1.0);
                                 ^

and -flto bypassed the system_header pragma somehow.