https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114945
Bug ID: 114945
Summary: Sporadic std::vector::resize() -Wstringop-overflow or
-Warray-bounds warning with gcc 14
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: nilsgladitz at gmail dot com
Target Milestone: ---
Created attachment 58103
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=58103&action=edit
Testcase
Initially seen with a Ubuntu specific GCC 14 x86-64 snapshot but also
reproduced with a vanilla arm32 build of GCC 14.1-rc1. Not seen with GCC 13.1.
I see there are a couple of issues which sound similar or related (e.g. bugs
113664, 106185, 105823, 105746) but I can't really tell if this is a duplicate
or regression of a previously fixed issue.
The reduced attached test case compiled with
g++-14 -std=c++20 -O2 case1.cpp
Produces the warning:
/usr/include/c++/14/bits/stl_algobase.h:972:25: warning: ‘void*
__builtin_memset(void*, int, long unsigned int)’ writing 3 bytes into a region
of size 0 overflows the destination [-Wstringop-overflow=]
972 | __builtin_memset(__first, static_cast<unsigned char>(__tmp),
__len);
|
~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Adding -Wall replaces the above warning with this new warning:
/usr/include/c++/14/bits/stl_algobase.h:972:25: warning: ‘void*
__builtin_memset(void*, int, long unsigned int)’ offset [0, 2] is out of the
bounds [0, 0] [-Warray-bounds=]
972 | __builtin_memset(__first, static_cast<unsigned char>(__tmp),
__len);
|
~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Also recreated this on godbolt: https://godbolt.org/z/rYx9q7Ke1
