https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100516
--- Comment #1 from vopl at bk dot ru ---
Please look at the following code, it throws an unexpected warning
[-Wstringop-overread].
$ cat b11.cpp && echo EOFFFFF
#include <deque>
void f()
{
std::initializer_list<char> il{};
std::deque<char>{il};
}
EOFFFFF
$ g++-11.1.0 -v -O2 -c b11.cpp
Using built-in specs.
COLLECT_GCC=g++-11.1.0
Target: x86_64-pc-linux-gnu
Configured with:
/var/tmp/portage/sys-devel/gcc-11.1.0/work/gcc-11.1.0/configure
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --prefix=/usr
--bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/11.1.0
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/11.1.0
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/11.1.0/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/11.1.0/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/include/g++-v11
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/11.1.0/python
--enable-languages=c,c++,fortran --enable-obsolete --enable-secureplt
--disable-werror --with-system-zlib --disable-nls --enable-checking=release
--with-bugurl=https://bugs.gentoo.org/ --with-pkgversion='Gentoo 11.1.0 p1'
--disable-esp --enable-libstdcxx-time --with-build-config=bootstrap-lto
--enable-shared --enable-threads=posix --enable-__cxa_atexit
--enable-clocale=gnu --enable-multilib --with-multilib-list=m32,m64
--disable-fixed-point --enable-targets=all --enable-libgomp --disable-libssp
--disable-libada --enable-systemtap --disable-valgrind-annotations
--enable-vtable-verify --with-zstd --enable-lto --with-isl
--disable-isl-version-check --enable-default-pie --disable-default-ssp
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.1.0 (Gentoo 11.1.0 p1)
COLLECT_GCC_OPTIONS='-v' '-O2' '-c' '-shared-libgcc' '-mtune=generic'
'-march=x86-64'
/usr/libexec/gcc/x86_64-pc-linux-gnu/11.1.0/cc1plus -quiet -v -D_GNU_SOURCE
./b11.cpp -quiet -dumpbase b11.cpp -dumpbase-ext .cpp -mtune=generic
-march=x86-64 -O2 -version -o /tmp/ccLiGLAe.s
GNU C++17 (Gentoo 11.1.0 p1) version 11.1.0 (x86_64-pc-linux-gnu)
compiled by GNU C version 11.1.0, GMP version 6.2.1, MPFR version
4.1.0, MPC version 1.2.1, isl version isl-0.23-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring nonexistent directory "/usr/local/include"
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/../../../../x86_64-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/include/g++-v11
/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/include/g++-v11/x86_64-pc-linux-gnu
/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/include/g++-v11/backward
/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/include
/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/include-fixed
/usr/include
End of search list.
GNU C++17 (Gentoo 11.1.0 p1) version 11.1.0 (x86_64-pc-linux-gnu)
compiled by GNU C version 11.1.0, GMP version 6.2.1, MPFR version
4.1.0, MPC version 1.2.1, isl version isl-0.23-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: bf86c5c567158ff2074c3c886a72c867
In file included from
/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/include/g++-v11/deque:60,
from ./b11.cpp:1:
In static member function 'static _Tp* std::__copy_move<_IsMove, true,
std::random_access_iterator_tag>::__copy_m(const _Tp*, const _Tp*, _Tp*) [with
_Tp = char; bool _IsMove = false]',
inlined from '_OI std::__copy_move_a2(_II, _II, _OI) [with bool _IsMove =
false; _II = const char*; _OI = char*]' at
/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/include/g++-v11/bits/stl_algobase.h:495:30,
inlined from '_OI std::__copy_move_a1(_II, _II, _OI) [with bool _IsMove =
false; _II = const char*; _OI = char*]' at
/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/include/g++-v11/bits/stl_algobase.h:522:42,
inlined from '_OI std::__copy_move_a(_II, _II, _OI) [with bool _IsMove =
false; _II = const char*; _OI = char*]' at
/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/include/g++-v11/bits/stl_algobase.h:529:31,
inlined from '_OI std::copy(_II, _II, _OI) [with _II = const char*; _OI =
char*]' at
/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/include/g++-v11/bits/stl_algobase.h:620:7,
inlined from 'static _ForwardIterator
std::__uninitialized_copy<true>::__uninit_copy(_InputIterator, _InputIterator,
_ForwardIterator) [with _InputIterator = const char*; _ForwardIterator =
char*]' at
/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/include/g++-v11/bits/stl_uninitialized.h:110:27,
inlined from '_ForwardIterator std::uninitialized_copy(_InputIterator,
_InputIterator, _ForwardIterator) [with _InputIterator = const char*;
_ForwardIterator = char*]' at
/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/include/g++-v11/bits/stl_uninitialized.h:151:15,
inlined from '_ForwardIterator std::__uninitialized_copy_a(_InputIterator,
_InputIterator, _ForwardIterator, std::allocator<_Tp>&) [with _InputIterator =
const char*; _ForwardIterator = char*; _Tp = char]' at
/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/include/g++-v11/bits/stl_uninitialized.h:333:37,
inlined from 'void std::deque<_Tp,
_Alloc>::_M_range_initialize(_ForwardIterator, _ForwardIterator,
std::forward_iterator_tag) [with _ForwardIterator = const char*; _Tp = char;
_Alloc = std::allocator<char>]' at
/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/include/g++-v11/bits/deque.tcc:463:33,
inlined from 'std::deque<_Tp, _Alloc>::deque(std::initializer_list<_Tp>,
const allocator_type&) [with _Tp = char; _Alloc = std::allocator<char>]' at
/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/include/g++-v11/bits/stl_deque.h:958:21,
inlined from 'void f()' at ./b11.cpp:6:10:
/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/include/g++-v11/bits/stl_algobase.h:431:30:
warning: 'void* __builtin_memcpy(void*, const void*, long unsigned int)'
reading 1 or more bytes from a region of size 0 [-Wstringop-overread]
431 | __builtin_memmove(__result, __first, sizeof(_Tp) * _Num);
| ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
COLLECT_GCC_OPTIONS='-v' '-O2' '-c' '-shared-libgcc' '-mtune=generic'
'-march=x86-64'
/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/../../../../x86_64-pc-linux-gnu/bin/as
-v --64 -o b11.o /tmp/ccLiGLAe.s
GNU assembler version 2.35.2 (x86_64-pc-linux-gnu) using BFD version (Gentoo
2.35.2 p1) 2.35.2
COMPILER_PATH=/usr/libexec/gcc/x86_64-pc-linux-gnu/11.1.0/:/usr/libexec/gcc/x86_64-pc-linux-gnu/11.1.0/:/usr/libexec/gcc/x86_64-pc-linux-gnu/:/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/:/usr/lib/gcc/x86_64-pc-linux-gnu/:/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/../../../../x86_64-pc-linux-gnu/bin/
LIBRARY_PATH=/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/:/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/../../../../lib64/:/lib/../lib64/:/usr/lib/../lib64/:/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/../../../../x86_64-pc-linux-gnu/lib/:/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-O2' '-c' '-shared-libgcc' '-mtune=generic'
'-march=x86-64'
