Il 07/12/2017 09:19, Christian Ehrlicher ha scritto:
From my pov <chrono> is a c++11 feature and since Qt5.9 needs c++11 the include gueard is superfluous. But I don't know if there is a supported platform which is still supported and chrono is not available...If the include guard is superflouos, I can create a patch. btw: the same goeas for qmutex.h and qobject.h
Although in general Qt > 5.6 requires C++11, we don't require _complete C++11 support_ from the compiler, in order to support as many platforms as possible. We don't (and cannot) use certain language features; some language feature needs protection via #ifdefs and other macros; and we unconditionally require minimal support from the Standard Library (as of now, I think, only containers, <new>, <type_traits>).
Support for <chrono> from the Standard Library is one of the things that Qt includes conditionally. I'm not sure which platform we want to support doesn't have it yet (QNX? maybe osX?), and since we don't want to drop that platform, we protect the inclusion. Yes, this also means you need to upgrade your compiler to support the has_include mechanism. (Or, patch your local version of Qt...)
Hope this helps, -- Giuseppe D'Angelo | [email protected] | Senior Software Engineer KDAB (UK) Ltd., a KDAB Group company | Tel: UK +44-1625-809908 KDAB - Qt, C++ and OpenGL Experts
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