https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94013
Bug ID: 94013
Summary: [10 Regression] library algos need to work around cwg
2094
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Keywords: rejects-valid
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: redi at gcc dot gnu.org
Target Milestone: ---
r271435 changed is_trivially_copyable_v<volatile int> to true, which breaks
this:
#include <algorithm>
int main()
{
volatile int i = 0;
volatile int j;
std::copy(&i, &i + 1, &j);
}
In file included from /home/jwakely/gcc/10/include/c++/10.0.1/algorithm:61,
from vol.cc:1:
/home/jwakely/gcc/10/include/c++/10.0.1/bits/stl_algobase.h: In instantiation
of 'static _Tp* std::__copy_move<_IsMove, true,
std::random_access_iterator_tag>::__copy_m(const _Tp*, const _Tp*, _Tp*) [with
_Tp = volatile int; bool _IsMove = false]':
/home/jwakely/gcc/10/include/c++/10.0.1/bits/stl_algobase.h:475:30: required
from '_OI std::__copy_move_a2(_II, _II, _OI) [with bool _IsMove = false; _II =
volatile int*; _OI = volatile int*]'
/home/jwakely/gcc/10/include/c++/10.0.1/bits/stl_algobase.h:509:42: required
from '_OI std::__copy_move_a1(_II, _II, _OI) [with bool _IsMove = false; _II =
volatile int*; _OI = volatile int*]'
/home/jwakely/gcc/10/include/c++/10.0.1/bits/stl_algobase.h:517:31: required
from '_OI std::__copy_move_a(_II, _II, _OI) [with bool _IsMove = false; _II =
volatile int*; _OI = volatile int*]'
/home/jwakely/gcc/10/include/c++/10.0.1/bits/stl_algobase.h:572:7: required
from '_OI std::copy(_II, _II, _OI) [with _II = volatile int*; _OI = volatile
int*]'
vol.cc:7:27: required from here
/home/jwakely/gcc/10/include/c++/10.0.1/bits/stl_algobase.h:423:24: error:
invalid conversion from 'volatile void*' to 'void*' [-fpermissive]
423 | __builtin_memmove(__result, __first, sizeof(_Tp) * _Num);
| ^~~~~~~~
| |
| volatile void*
<built-in>: note: initializing argument 1 of 'void* __builtin_memmove(void*,
const void*, long unsigned int)'
/home/jwakely/gcc/10/include/c++/10.0.1/bits/stl_algobase.h:423:34: error:
invalid conversion from 'const volatile void*' to 'const void*' [-fpermissive]
423 | __builtin_memmove(__result, __first, sizeof(_Tp) * _Num);
| ^~~~~~~
| |
| const volatile void*
<built-in>: note: initializing argument 2 of 'void* __builtin_memmove(void*,
const void*, long unsigned int)'
It's no longer possible to use is_trivially_copyable to tell if something can
be copied with memcpy.
There are probably similar issues with the algos using memcmp (std::equal,
std::lexicographical_compare).
