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


Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE> writes:

> Jonathan Wakely <jwakely.gcc@gmail.com> writes:
>
>> This alters the configure script to enable C++11 thread library
>> features based on targets that are known to support the features,
>> rather than based on link tests which are disabled by default.  With
>> Glibc 2.17 this enables a nanosecond resolution std::system_clock in
>> the default configuration, yay!
>>
>> I've tested this on two versions of Fedora and Debian, but would be
>> grateful for test results on Solaris, Cygwin and BSD targets, and for
>> cross-compilers to any of those targets.
>
> Apart from the abi_check failure already reported, I get the following
> testsuite regressions on Solaris 10/x86:
>
> FAIL: 30_threads/async/54297.cc (test for excess errors)
> WARNING: 30_threads/async/54297.cc compilation failed to produce executable
> FAIL: 30_threads/condition_variable_any/53830.cc (test for excess errors)
> WARNING: 30_threads/condition_variable_any/53830.cc compilation failed to produ
> e executable
> FAIL: 30_threads/this_thread/3.cc (test for excess errors)
> WARNING: 30_threads/this_thread/3.cc compilation failed to produce executable
> FAIL: 30_threads/this_thread/4.cc (test for excess errors)
> WARNING: 30_threads/this_thread/4.cc compilation failed to produce executable
> FAIL: 30_threads/thread/native_handle/cancel.cc (test for excess errors)
> WARNING: 30_threads/thread/native_handle/cancel.cc compilation failed to produc
> e executable
>
> All of them have the same root cause:
>
> Excess errors:
> Undefined                       first referenced
>  symbol                             in file
> nanosleep                           /var/tmp//ccQhmiwd.o  (symbol belongs to implicit dependency /lib/librt.so.1)
> ld: fatal: symbol referencing errors. No output written to ./54297.exe
> collect2: error: ld returned 1 exit status
>
> It seems that now every single C++ program needs to be linked with -lrt,
> not only libstdc++.so.  This will also happen on Solaris 9 (bootstrap
> still running), while on Solaris 11 nanosleep and the others were
> integrated into libc.so.1.
>
> Speaking of Solaris 9, there's another caveat: unlike Solaris 10 and up,
> CLOCK_MONOTONIC isn't defined, while the equivalent non-standard
> CLOCK_HIGHRES is.  Instead of handling this in
> libstdc++-v3/src/c++11/chrono.cc directly, I've chosen the following
> route which allows libstdc++ to build on Solaris 9:
>
> 2013-05-22  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
>
> 	* config/os/solaris/solaris2.9/os_defines.h [!CLOCK_MONOTONIC]
> 	(CLOCK_MONOTONIC): Define.

The Solaris 9 (i386-pc-solaris2.9) bootstrap has now completed
successfully, so the patch above seems to be sound.  Ok for mainline?

Astonishingly, the only failure I see is abi_check.  The nanosleep error
above seems to be linker version dependent.

	Rainer

-- 
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University


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