https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107927
Bug ID: 107927
Summary: vector::push_back gives array bounds warning with
optimization and undefined sanitizer
Product: gcc
Version: 12.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: larsbj at gullik dot org
Target Milestone: ---
Created attachment 53988
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53988&action=edit
Pre-processed source
This looks very similar to Bug 107852, but different to warrant a report imho.
gcc --version
gcc (GCC) 12.2.1 20221121 (Red Hat 12.2.1-4)
The preprocessed file has been reduced from something much larger with
Compiling the pre-processed file with cvise. The seemingly similar test case:
#include <initializer_list>
#include <vector>
struct Foo {
Foo(std::initializer_list<unsigned> l) : v(l) { v.push_back(5); }
struct::vector<unsigned> v;
};
void make() { Foo{{}}; }
does not exibit the same error as the original or preprocessed code.
g++ g++ -Warray-bounds -O2 -fsanitize=undefined -std=gnu++20 -c test.ii
(note that the original code requires -fsanitize=undefined to fail, the
preprocessed code does not.)
gives:
In function ‘int std::construct_at(_Tp) [with _Tp = unsigned int*]’,
inlined from ‘static int std::allocator_traits<std::allocator<_Tp>
>::construct(allocator_type, _Up) [with _Up = unsigned int*; _Tp = unsigned
int]’ at :59:17,
inlined from ‘int std::vector::push_back(int)’ at :114:46,
inlined from ‘RTCPfeedback::RTCPfeedback(std::initializer_list<unsigned
int>)’ at :128:71,
inlined from ‘int makeEmptyRR()’ at :131:17:
:4:56: warning: array subscript 1 is outside array bounds of ‘unsigned int [1]’
[-Warray-bounds]
In member function ‘unsigned int* std::__new_allocator::allocate(long int)’,
inlined from ‘static _Tp* std::allocator_traits<std::allocator<_Tp>
>::allocate(allocator_type, size_type) [with _Tp = unsigned int]’ at :56:24,
inlined from ‘unsigned int* std::_Vector_base::_M_allocate(long int)’ at
:103:53,
inlined from ‘void std::vector::_M_range_initialize(_ForwardIterator,
_ForwardIterator, random_access_iterator_tag) [with _ForwardIterator = unsigned
int*]’ at :120:20,
inlined from ‘std::vector::vector(std::initializer_list<unsigned int>)’ at
:112:24,
inlined from ‘RTCPfeedback::RTCPfeedback(std::initializer_list<unsigned
int>)’ at :128:53,
inlined from ‘int makeEmptyRR()’ at :131:17:
:7:48: note: at offset 4 into object of size 4 allocated by ‘operator new’
