2.4.10-pre9 min/max raises "const" warnings

2.4.10-pre9 min/max raises "const" warnings

[Alexander Stohr]

try this one:

  int a, b, c, d;
  d = min( a, min( b, c ));

and you will see a gnu c warning about multiple const qualifiers.
(this might depend on the warning level you drive.)

fix it with this code:

  #define min(x,y) ({ \

      const typeof(x) _x = (x);       \

      const typeof(y) _y = (y);       \

      (void) (&_x == &_y);            \

      (_x < _y) ? (typeof(x)) _x : (typeof(y)) _y; })

simply the last line has changed towards linux kernel patch-2.4.10-pre9 from
ftp.
the same change should apply for the max() macro.

i am yet not sure if the used "? :" operator set does qualify as
a left-value. maybe this could be another important reason why 
return types here should stay identical to input types.

regards AlexS.

PS: i am not subscribed to this list.

Re: 2.4.10-pre9 min/max raises "const" warnings

[Andreas Schwab]

Alexander Stohr <AlexanderS@ati.com> writes:

|> i am yet not sure if the used "? :" operator set does qualify as
|> a left-value.

For Standard C it isn't, but for GNU C it is.

Andreas.

-- 
Andreas Schwab                                  "And now for something
Andreas.Schwab@suse.de				completely different."
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Re: 2.4.10-pre9 min/max raises "const" warnings

[J . A . Magallon]

On 20010914 Andreas Schwab wrote:
>Alexander Stohr <AlexanderS@ati.com> writes:
>
>|> i am yet not sure if the used "? :" operator set does qualify as
>|> a left-value.
>
>For Standard C it isn't, but for GNU C it is.
>

Perhaps it is nonsense, but, as the kernel already uses gcc-specific features,
the gcc folks could extend to C th '<?' and '>?' operators from C++, so

#define max(a,b) (a >? b)
#define min(a,b) (a <? b)

It works at least since 2.95.2. gcc3 warns about signs in -Wall mode.

-- 
J.A. Magallon                           #  Let the source be with you...        
mailto:jamagallon@able.es
Mandrake Linux release 8.1 (Cooker) for i586
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