@section @file{stdalign.h}
POSIX specification:@* Not in POSIX yet, but we expect it will be.
-ISO C1X @url{http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf}
+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++0X @url{http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3242.pdf}
+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
@itemize
@item
This header file is missing on most circa-2011 platforms.
+@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
@code{_Alignas} and @code{alignas} are not always supported;
on platforms lacking support, the
macro @code{__alignas_is_defined} is not defined.
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.
The Sun C 5.11 compiler sometimes mishandles the alignment of multiple
external variables that are declared close together with
@code{_Alignas}/@code{alignas}. This compiler bug causes the Gnulib
-module @code{stdalign-tests} to fail.
+module @code{stdalign-tests} to fail. The Sun Studio Developer Bug
+Report Review Team assigned the internal review ID 2125432 (dated
+2011-11-01) to this issue.
@item
-@code{<stdalign.h>} must be #included before @samp{_Alignas} and
-@samp{_Alignof} can be used.
+@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.