kc3-lang/gnulib/doc/posix-headers/stdalign.texi

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• Hash : e603220f
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  Date : 2020-09-20T15:42:43
  

  test-stdalign: test Oracle Studio better
  
  * doc/posix-headers/stdalign.texi (stdalign.h):
  * tests/test-stdalign.c (main):
  Sun Studio Bug #2125432 seems to be fixed.
  

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• doc/posix-headers/stdalign.texi

• @node stdalign.h
  @section @file{stdalign.h}
  
  POSIX specification:@* Not in POSIX yet, but we expect it will be.
  ISO C11 (latest free draft
  @url{http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf})
  sections 6.5.3.4, 6.7.5, 7.15.
  C++11 (latest free draft
  @url{http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3242.pdf})
  section 18.10.
  
  Gnulib module: stdalign
  
  Portability problems fixed by Gnulib:
  @itemize
  @item
  This header file is missing on many platforms:
  FreeBSD 6.4, NetBSD 7.1, OpenBSD 6.7, Minix 3.3.0, AIX 7.1, HP-UX 11.31, IRIX 6.5, Solaris 11.3, mingw, MSVC 14, Android 9.0.
  @item
  Clang 3.0's @code{<stdalign.h>} does not define @code{alignof}/@code{_Alignof}.
  @item
  The @code{alignof} and @code{_Alignof} macros return too large values for
  the types @code{double} and @code{long long} in GCC 4.7.0.
  @end itemize
  
  Portability problems not fixed by Gnulib:
  @itemize
  @item
  In ISO C11, the operand of @code{alignof}/@code{_Alignof} must be a
  parenthesized type.  Recent versions of GCC support an extension in
  which the operand can also be a unary expression, as with
  @code{sizeof}.  The Gnulib substitute does not support this extension.
  @item
  On most pre-C11 platforms, the operand of
  @code{alignof}/@code{_Alignof} cannot be a structure type containing a
  flexible array member.
  @item
  @code{_Alignas} and @code{alignas} are not always supported;
  on platforms lacking support, the
  macro @code{__alignas_is_defined} is not defined.
  Supported compilers include GCC, IBM C, Sun C 5.9 and later,
  and MSVC 7.0 and later.
  @item
  Some compilers do not support alignment via
  @code{alignas}/@code{_Alignas} of @code{auto} variables (i.e.,
  variables on the stack).  They diagnose and ignore the alignment: Sun
  C 5.11.
  @item
  Some linkers do not support operands of @code{_Alignas}/@code{alignas}
  that are greater than 8: mingw.
  @item
  Some compilers require the operand of @code{_Alignas}/@code{alignas}
  to be a single integer constant, not an expression: MSVC 7.0 through
  at least 10.0.
  @item
  The Sun C 5.13 compiler sometimes mishandles the alignment of multiple
  external variables that are declared close together with
  @code{_Alignas}/@code{alignas}.  The Sun Studio Developer Bug
  Report Review Team assigned the internal review ID 2125432 (dated
  2011-11-01) to this issue.  The bug appears to be fixed in Sun C 5.15,
  also known as Oracle Developer Studio 12.6.
  @item
  @code{<stdalign.h>} must be #included before @code{_Alignas} and
  @code{_Alignof} can be used.
  @item
  You cannot assume that @code{_Alignas} and @code{_Alignof} are reserved words;
  they might be macros.
  @end itemize
  

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