On Feb 17, 2023, Jonathan Wakely <jwakely....@gmail.com> wrote:
> The proper fix is to ensure the program has a non-weak reference to
> pthread_join without extra help (or use a recent glibc where it always
> works).
Indeed! How about this? Regstrapped on x86_64-linux-gnu, also tested
on arm-vx7r2 (gcc-12); verified that strong references are present in
95989.o, but not in libstdc++.a or .so. Ok to install?
(nit: the static local in a ctor of a template class may make for
multiple copies. Maybe a non-template always-inline function called by
all instantiations would be better.)
link pthread_join from std::thread ctor
Like pthread_create, pthread_join may fail to be statically linked in
absent strong uses, so add to user code strong references to both when
std::thread objects are created.
for libstdc++-v3/ChangeLog
* include/bits/std_thread.h (std::thread ctor): Add strong
reference to pthread_join.
---
libstdc++-v3/include/bits/std_thread.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/libstdc++-v3/include/bits/std_thread.h
b/libstdc++-v3/include/bits/std_thread.h
index adbd3928ff783..4bda350fa2c7b 100644
--- a/libstdc++-v3/include/bits/std_thread.h
+++ b/libstdc++-v3/include/bits/std_thread.h
@@ -145,6 +145,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#ifdef GTHR_ACTIVE_PROXY
// Create a reference to pthread_create, not just the gthr weak symbol.
auto __depend = reinterpret_cast<void(*)()>(&pthread_create);
+ static auto __attribute__((__used__)) __depend_join = &pthread_join;
#else
auto __depend = nullptr;
#endif
--
Alexandre Oliva, happy hacker https://FSFLA.org/blogs/lxo/
Free Software Activist GNU Toolchain Engineer
Disinformation flourishes because many people care deeply about injustice
but very few check the facts. Ask me about <https://stallmansupport.org>
