qt5base-lts/tools/configure
Thiago Macieira 3d7586b760 Auto-detect whether 64-bit std::atomic really works
The C++ standard says it must, but some badly-configured toolchains seem
to be lacking support.

In particular, for some 32-bit platforms without native support for
them, GCC implements 64-bit atomics via out-of-line functions in
libatomic. If that library is missing... well, then std::atomic 64-bit
doesn't work and we mustn't try to use it.

This was found when trying to compile Qt 5.6 for MIPS 32-bit:

Linking library libQt5Core.so.5.6.0
.obj/qsimd.o: In function `std::__atomic_base<unsigned long long>::load(std::memory_order) const':
/opt/poky/1.7/sysroots/mips32r2-poky-linux/usr/include/c++/4.9.1/bits/atomic_base.h:500: undefined reference to `__atomic_load_8'
.obj/qsimd.o: In function `std::__atomic_base<unsigned long long>::store(unsigned long long, std::memory_order)':
/opt/poky/1.7/sysroots/mips32r2-poky-linux/usr/include/c++/4.9.1/bits/atomic_base.h:478: undefined reference to `__atomic_store_8'

Yocto bug report: https://bugzilla.yoctoproject.org/show_bug.cgi?id=8274

Change-Id: I42e7ef1a481840699a8dffff140224d6614e5c36
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
2015-09-22 22:46:08 +00:00
..
configure_pch.h Update copyright headers 2015-02-11 06:49:51 +00:00
configure.pro Merge remote-tracking branch 'origin/5.5' into dev 2015-06-03 10:23:56 +02:00
configureapp.cpp Auto-detect whether 64-bit std::atomic really works 2015-09-22 22:46:08 +00:00
configureapp.h Detect which C++ standard edition the compiler defaults to 2015-08-25 06:25:11 +00:00
environment.cpp remove $INCLUDE/$LIB hack for mingw 2015-05-12 09:10:18 +00:00
environment.h Add mingw GCC Version to qconfig.pri 2015-03-25 11:13:19 +00:00
main.cpp Update copyright headers 2015-02-11 06:49:51 +00:00
Makefile.mingw Merge remote-tracking branch 'origin/5.5' into dev 2015-06-03 10:23:56 +02:00
Makefile.win32 Merge remote-tracking branch 'origin/5.5' into dev 2015-06-03 10:23:56 +02:00
tools.cpp Run license checker in qmake 2015-05-27 10:23:10 +00:00
tools.h Update copyright headers 2015-02-11 06:49:51 +00:00