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Message-ID: <51DDDC6B.3090401@t-online.de>
Date: Thu, 11 Jul 2013 00:12:59 +0200
From: Christian Franke <Christian DOT Franke AT t-online DOT de>
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To: cygwin AT cygwin DOT com
Subject: i686-w64-mingw32-gcc 4.7.3: ignores __attribute__((packed)), regression?
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The new MinGW-w64 4.7.3 gcc apparently ignores __attribute__((packed)). 
Cygwin's gcc 4.7.3 and older MinGW-w64 4.5.3 work as expected.


Testcase:

$ cat packed.c
struct packed { char a; short b; } __attribute__((packed));
int size = sizeof(struct packed);


$ i686-w64-mingw32-gcc --version
i686-w64-mingw32-gcc (GCC) 4.7.3
...
$ i686-w64-mingw32-gcc -S packed.c

$ cat packed.s
...
_size:
         .long   4


$ gcc --version
gcc (GCC) 4.7.3
...
$ gcc -S packed.c

$ cat packed.s
...
_size:
         .long   3


$ x86_64-w64-mingw32-gcc --version
x86_64-w64-mingw32-gcc (GCC) 4.5.3
...
$ x86_64-w64-mingw32-gcc -S packed.c

$ cat packed.s
...
size:
         .long   3


If #pragma pack(1) is used instead, it works as expected also with 
i686-w64-mingw32-gcc 4.7.3.

(Upstream?) bug ?


Christian


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