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Force the use of the C++11 alignof keyword instead of an extension 

If the compiler supports C++11 alignof, let's use it. No point in
perpetuating the use of __alignof__ or __alignof.

There's a fallback implementation in qglobal.h that works even without
compiler extensions. We can't drop it just yet (alignas is not a
required C++11 feature), but at this point I doubt that fallback is used
anywhere anymore.

The tst_compiler test was wrong to use alignof(variable). That's not
permitted by the standard nor would it work with our fallback
implementation. MSVC 2015 enforces this, but ICC, GCC and Clang don't.

Change-Id: Ifea6e497f11a461db432ffff1448abfa86672c63
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
bb10
Thiago Macieira 2016-04-25 10:59:31 -07:00
parent 9e9888f69a
commit 0f559a2d99
2 changed files with 6 additions and 4 deletions
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3
src/corelib/global/qcompilerdetection.h
View File

@ -1053,7 +1053,8 @@
# define Q_DECL_NOTHROW Q_DECL_NOEXCEPT
#endif
#if defined(Q_COMPILER_ALIGNOF) && !defined(Q_ALIGNOF)
#if defined(Q_COMPILER_ALIGNOF)
# undef Q_ALIGNOF
# define Q_ALIGNOF(x) alignof(x)
#endif

7
tests/auto/other/compiler/tst_compiler.cpp
View File

@ -636,9 +636,10 @@ void tst_Compiler::cxx11_alignas()
#ifndef Q_COMPILER_ALIGNAS
QSKIP("Compiler does not support C++11 feature");
#else
alignas(double) char c;
Q_UNUSED(c);
QCOMPARE(Q_ALIGNOF(c), Q_ALIGNOF(double));
struct S {
alignas(double) char c;
};
QCOMPARE(Q_ALIGNOF(S), Q_ALIGNOF(double));
#endif
}