strict aliasing can not be turned off

[Liu, Lei]

Ian Lance Taylor wrote:
> "Liu, Lei"<lei.liu2@windriver.com>  writes:
>
>> Here is my program.
>>
>> #include<stdio.h>
>>
>> struct s1 {
>>    unsigned int a,b,c;
>> };
>> struct s2 {
>>    unsigned int b,c;
>> };
>>
>> int main(void)
>> {
>>    struct s1 s;
>>    s.c =  0xdead;
>>    struct s2 *p = (struct s2*)&s.b;
>>    p->c = 0xbeef;
>>    printf("s.c=%04x\n", s.c);
>>    return 0;
>> }
>>
>> I compile this code with '-O2' flag and get a 's.c=dead'. It's
>> reasonable under strict aliasing rule. But when I recompile it with
>> -O2 -fno-strict-aliasing', the output is still 's.c=dead'.
>
> I don't see this when I use -fno-strict-aliasing.  I see the "s.c=beef"
> as you expect.  That is with gcc 4.4.3 on x86_64.  What version of gcc
> are you using?
>
> Ian
>
I'm using gcc 4.3.3.

Using built-in specs.
Target: i486-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 
4.3.3-5ubuntu4' --with-bugurl=file:///usr/share/doc/gcc-4.3/README.Bugs 
--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr 
--enable-shared --with-system-zlib --libexecdir=/usr/lib 
--without-included-gettext --enable-threads=posix --enable-nls 
--with-gxx-include-dir=/usr/include/c++/4.3 --program-suffix=-4.3 
--enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc 
--enable-mpfr --enable-targets=all --with-tune=generic 
--enable-checking=release --build=i486-linux-gnu --host=i486-linux-gnu 
--target=i486-linux-gnu
Thread model: posix
gcc version 4.3.3 (Ubuntu 4.3.3-5ubuntu4)

Is it a fixed bug of gcc?

Lei