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Re: [patch] Default to --enable-libstdcxx-time=auto


On Fri, May 24, 2013 at 09:57:05AM +0200, Jakub Jelinek wrote:
> Thus, what about this version (just slightly modified, headers remain the
> same, but we export _ZNSt6chrono12steady_clock3nowEv@@GLIBCXX_3.4.19
> even if monotonic clock isn't supported, it will just be work the same as
> _ZNSt6chrono12system_clock3nowEv@@GLIBCXX_3.4.11 .  Programs compiled
> against headers of the same libstdc++ as will be linked in dynamically
> won't see a change, because they will never use this symbol of monotonic
> clocks weren't determined to be there at configure time.  And we have a
> fallback for the unlikely matching of newer headers with older libstdc++,
> it will work roughly as before (in that steady_clock::now () will not be
> steady), just with the tiny exception that in that case the code could
> see that steady_clock::is_steady is true rather than false (but, can't
> the code assume it from the standard anyway)?
> 
> I've also added the #ifdef HAVE_SYMVER_SYMBOL_RENAMING_RUNTIME_SUPPORT
> guards in gnu.ver.

Oops, posted too early, while that worked on Linux due to
_GLIBCXX_USE_CLOCK_MONOTONIC_SYSCALL, it didn't work when
_GLIBCXX_USE_CLOCK_MONOTONIC wasn't defined, the return of the other clock
now() result resulted in error.

So here is once more updated version that works even when
_GLIBCXX_USE_CLOCK_MONOTONIC isn't defined.

	Jakub

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