https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120680
Bug ID: 120680
Summary: [nvptx] Linker errors with absent weak symbol
'zoneinfo_dir_override'
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Keywords: rejects-valid
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: burnus at gcc dot gnu.org
CC: tschwinge at gcc dot gnu.org
Target Milestone: ---
Target: nvptx
I get link errors with -O0 for some C++ programs failing with:
unresolved symbol _ZN9__gnu_cxx21zoneinfo_dir_overrideEv
----------------------- Example -----------------------
#include <iostream>
int main()
{
#pragma omp target
std::cout << "Hello World" << std::endl;
}
-------------------------------------------------------
It works with AMD GCN. The problem seems to be the lacking support of nvptx for
weak symbols.
Looking at libstdc++-v3/src/c++20/tzdb.cc, the current code has:
-------------------------------------------------------
namespace __gnu_cxx
{
#ifdef _AIX
// Cannot override weak symbols on AIX.
const char* (*zoneinfo_dir_override)() = nullptr;
#else
[[gnu::weak]] const char* zoneinfo_dir_override();
#if defined(__APPLE__) || defined(__hpux__) \
|| (defined(__VXWORKS__) && !defined(__RTP__))
// Need a weak definition for Mach-O et al.
[[gnu::weak]] const char* zoneinfo_dir_override()
{
#ifdef _GLIBCXX_ZONEINFO_DIR
return _GLIBCXX_ZONEINFO_DIR;
#else
return nullptr;
#endif
}
#endif
#endif
}
-------------------------------------------------------
And later:
-------------------------------------------------------
if (__gnu_cxx::zoneinfo_dir_override)
{
if (auto override_dir = __gnu_cxx::zoneinfo_dir_override())
path = override_dir;
-------------------------------------------------------
This obvious fails as the 'if' does not evaluate to false.
Solution: Either the __APPLE__/__HPUX_/… or the _AIX seems to make sense for
nvptx as well.
