https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103332
Bug ID: 103332 Summary: Spurious -Wstringop-overflow warnings in libstdc++ tests Product: gcc Version: 12.0 Status: UNCONFIRMED Keywords: diagnostic Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: redi at gcc dot gnu.org Blocks: 88443 Target Milestone: --- In the $objdir/$target/libstdc++-v3/testsuite dir, running: make check RUNTESTFLAGS="conformance.exp=21_strings/basic_string/operators/char/1.cc --target_board=unix/-D_GLIBCXX_DEBUG" Results in: In file included from /home/jwakely/build/powerpc64le-unknown-linux-gnu/libstdc++-v3/include/string:40,^M from /home/jwakely/src/gcc/libstdc++-v3/testsuite/21_strings/basic_string/operators/char/1.cc:22:^M In static member function 'static std::char_traits<char>::char_type* std::char_traits<char>::copy(std::char_traits<char>::char_type*, const std::char_traits<char>::char_type*, std::size_t)',^M inlined from 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]' at /home/jwakely/build/powerpc64le-unknown-linux-gnu/libstdc++-v3/include/bits/basic_string.h:675,^M inlined from 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(std::__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]' at /home/jwakely/build/powerpc64le-unknown-linux-gnu/libstdc++-v3/include/bits/basic_string.h:3552,^M inlined from 'int test01()' at /home/jwakely/src/gcc/libstdc++-v3/testsuite/21_strings/basic_string/operators/char/1.cc:34:^M /home/jwakely/build/powerpc64le-unknown-linux-gnu/libstdc++-v3/include/bits/char_traits.h:423: warning: 'void* __builtin_memcpy(void*, const void*, long unsigned int)' writing 17 bytes into a region of size 16 overflows the destination [-Wstringop-overflow=]^M /home/jwakely/src/gcc/libstdc++-v3/testsuite/21_strings/basic_string/operators/char/1.cc: In function 'int test01()':^M /home/jwakely/src/gcc/libstdc++-v3/testsuite/21_strings/basic_string/operators/char/1.cc:34: note: at offset 16 into destination object '<anonymous>' of size 32^M FAIL: 21_strings/basic_string/operators/char/1.cc (test for excess errors) Excess errors: /home/jwakely/build/powerpc64le-unknown-linux-gnu/libstdc++-v3/include/bits/char_traits.h:423: warning: 'void* __builtin_memcpy(void*, const void*, long unsigned int)' writing 17 bytes into a region of size 16 overflows the destination [-Wstringop-overflow=] And: make check RUNTESTFLAGS="conformance.exp=21_strings/basic_string/capacity/char/1.cc --target_board=unix/-std=gnu++20" results in: In file included from /home/jwakely/build/powerpc64le-unknown-linux-gnu/libstdc++-v3/include/string:40,^M from /home/jwakely/src/gcc/libstdc++-v3/testsuite/21_strings/basic_string/capacity/char/1.cc:22:^M In static member function 'static constexpr std::char_traits<char>::char_type* std::char_traits<char>::copy(std::char_traits<char>::char_type*, const std::char_traits<char>::char_type*, std::size_t)',^M inlined from 'static constexpr void std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_S_copy(_CharT*, const _CharT*, std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]' at /home/jwakely/build/powerpc64le-unknown-linux-gnu/libstdc++-v3/include/bits/basic_string.h:423,^M inlined from 'static constexpr void std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_S_copy(_CharT*, const _CharT*, std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]' at /home/jwakely/build/powerpc64le-unknown-linux-gnu/libstdc++-v3/include/bits/basic_string.h:418,^M inlined from 'constexpr std::__cxx11::basic_string<_CharT, _Traits, _Allocator>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_M_append(const _CharT*, std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]' at /home/jwakely/build/powerpc64le-unknown-linux-gnu/libstdc++-v3/include/bits/basic_string.tcc:417,^M inlined from 'constexpr std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::append(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]' at /home/jwakely/build/powerpc64le-unknown-linux-gnu/libstdc++-v3/include/bits/basic_string.h:1385,^M inlined from 'constexpr std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>&, const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]' at /home/jwakely/build/powerpc64le-unknown-linux-gnu/libstdc++-v3/include/bits/basic_string.h:3433,^M inlined from 'void test01()' at /home/jwakely/src/gcc/libstdc++-v3/testsuite/21_strings/basic_string/capacity/char/1.cc:102:^M /home/jwakely/build/powerpc64le-unknown-linux-gnu/libstdc++-v3/include/bits/char_traits.h:423: warning: 'void* __builtin_memcpy(void*, const void*, long unsigned int)' specified bound between 18446744073709551586 and 18446744073709551615 exceeds maximum object size 9223372036854775807 [-Wstringop-overflow=]^M FAIL: 21_strings/basic_string/capacity/char/1.cc (test for excess errors) Excess errors: /home/jwakely/build/powerpc64le-unknown-linux-gnu/libstdc++-v3/include/bits/char_traits.h:423: warning: 'void* __builtin_memcpy(void*, const void*, long unsigned int)' specified bound between 18446744073709551586 and 18446744073709551615 exceeds maximum object size 9223372036854775807 [-Wstringop-overflow=] And: make check RUNTESTFLAGS"=conformance.exp=experimental/filesystem/path/factory/u8path-char8_t.cc --target_board=unix/-std=gnu++20" results in: [...] FAIL: experimental/filesystem/path/factory/u8path-char8_t.cc (test for excess errors) Excess errors: /home/jwakely/build/powerpc64le-unknown-linux-gnu/libstdc++-v3/include/bits/char_traits.h:423: warning: 'void* __builtin_memcpy(void*, const void*, long unsigned int)' reading between 16 and 9223372036854775806 bytes from a region of size 10 [-Wstringop-overread] /home/jwakely/build/powerpc64le-unknown-linux-gnu/libstdc++-v3/include/bits/char_traits.h:423: warning: 'void* __builtin_memcpy(void*, const void*, long unsigned int)' reading between 16 and 9223372036854775806 bytes from a region of size 10 [-Wstringop-overread] These are all bogus, as far as I can tell. e.g. for the last one, we read 9 bytes from a string literal that is 10 bytes long (including the null) and memcpy it into a buffer that is 16 bytes in size. That doesn't overflow. Referenced Bugs: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88443 [Bug 88443] [meta-bug] bogus/missing -Wstringop-overflow warnings