[Bug target/52023] _Alignof (double) yields wrong value on x86

[joseph at codesourcery dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52023

--- Comment #11 from joseph at codesourcery dot com <joseph at codesourcery dot com> 2012-01-27 23:26:39 UTC ---
I should add: as a matter of ABI compatibility with programs doing what 
stddef.h does for max_align_t (double fields using 
__attribute__((__aligned__(__alignof__(double)))), etc.), it probably is 
best to distinguish between _Alignof (least ABI alignment for a type) and 
__alignof__ (greatest ABI alignment for a type) here.  C++11 will need 
examining to determine what is right for alignof there.  _Alignas(type) 
should of course match _Alignof.  _Alignof (expr) - the C11 keyword 
applied in the GNU extension of alignof (expr) - should continue to have 
the present semantics in the various special cases where the expression 
references a declaration, but otherwise should probably match _Alignof.