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Re: strict aliasing issue


> 
> Here's my reduced testcase:
> 
> typedef long GLint;
> extern void aglChoosePixelFormat(const GLint *);
> void find(const int *alistp) {
>    const int *blist;
>    int list[32];
>    if (alistp)
>      blist = alistp;
>    else {
>      list[3] = 42;       /* this store disappears with -O1 -fstrict- 
> aliasing */
>      blist = list;
>    }
>    aglChoosePixelFormat((GLint*)blist);
> }
> 
> (The original testcase is C++, from the FLTK project.)
> 
> If I compile this with -O1 -fstrict-aliasing, the "= 42" store  
> disappears.  I've confirmed this on mainline PPC and x86.
> 
> I'm not a language lawyer; is this a legal program?  (If the program  
> is legal, should I file a PR?)

This is legal as long as aglChoosePixelFormat only access it as int.

-- Pinski


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