https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104920
Bug ID: 104920
Summary: Unreliable results with memset-elt-size
Product: gcc
Version: og11 (devel/omp/gcc-11)
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: kouhzadi at rohumm dot com
Target Milestone: ---
Created attachment 52624
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52624&action=edit
4 examples where memset-elt-size fails, one where it's successful
* GCC versions: 10.3.1 and 11.2
* System type: GNU/Linux (amd64, aarch64, aarch32)
* Configured with: ../src/configure -v --with-pkgversion='Ubuntu
11.2.0-7ubuntu2' --with-bugurl=file:///usr/share/doc/gcc-11/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,m2 --prefix=/usr
--with-gcc-major-version-only --program-suffix=-11
--program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib
--enable-libphobos-checking=release --with-target-system-zlib=auto
--enable-objc-gc=auto --enable-multiarch --disable-werror --enable-cet
--with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32
--enable-multilib --with-tune=generic
--enable-offload-targets=nvptx-none=/build/gcc-11-ZPT0kp/gcc-11-11.2.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-11-ZPT0kp/gcc-11-11.2.0/debian/tmp-gcn/usr
--without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
--with-build-config=bootstrap-lto-lean --enable-link-serialization=2
* Command line: g++ -Wall -Wextra -O3 source.cpp
* Compiler output: none
* Expected compiler output: warning: ‘memset’ used with length equal to number
of elements without multiplication by element size [-Wmemset-elt-size]
* Sample code (more attached):
#include <cstring>
#include <array>
constexpr std::size_t ARRAY_LEN = 10u;
int main()
{
int arr[ARRAY_LEN];
std::memset(arr, 0, ARRAY_LEN); // OK, warning as expected
std::array<int, ARRAY_LEN> arr2;
std::memset(arr2.data(), 0, arr2.size()); // No warning; note that both
std::array::data() and std::array::size() are constexpr
return 0;
}
