On Tue, 7 Dec 2021 at 21:52, Florian Weimer wrote: > > * Jonathan Wakely: > > > On Tue, 7 Dec 2021, 21:20 Florian Weimer via Libstdc++, > > <libstd...@gcc.gnu.org> > > wrote: > > > > * Jonathan Wakely via Libstdc: > > > > > If necessary we could keep the terminate-on-cancellation behaviour as > > > _ZNSt18condition_variable4waitERSt11unique_lockISt5mutexE@GLIBCXX_3.4.11 > > > and export the new behaviour as @@GLIBCXX_3.4.30, although this patch > > > doesn't do that. > > > > Note that if this fix escapes into the wild and then you have to make > > the symbol version change, you will break newer applications. In a few > > cases in glibc, we proactively added aliases at a different symbol > > version, but with the same implementation (at first). > > > > To be safe, we probably should preserve the old behaviour for the old > > version of the symbol. If we decide that the new behaviour is always > > preferable, we could change that later by making the old symbol an > > alias for the new. If we don't decide that, we'll be glad we made it a > > separate symbol. > > On the other hand, with separate versions, it's possible to reintroduce > the old behavior at a later date, as a bugfix. It's not strictly > necessary to do that work upfront. It's just nice to have this option.
Ah yes, a new symbol version gives us more flexibility in every direction. > > I'll see if I can get it working with two versioned symbols. We don't > > actually do that in libstdc++ currently, we only have a single version > > of every symbol. > > Ping me if you want to discuss options. 8-> Thanks. I'll try it and let you know how I get on. > Out of curiosity—do you support building libstdc++ (the shared object) > with a different compiler than the included GCC? No. Even using a different GCC is unsupported. I know of two people who've tried using clang, for reasons. But it's unsupported. You can use the installed libstdc++ headers and libs with other non-GCC compilers, but not other versions of GCC. But you can't build it with anything except the GCC built from the same revision of the source tree.
