Re: double exclamation (!!) suckage in the kernel

[Al Viro]

On Sat, May 26, 2007 at 06:38:07PM +0200, Bodo Eggert wrote:
> Not exactly, if(foo) is the same as if( (int) foo), which is not
> guaranteed to result in non-null values for non-null pointers.

RTFStandard.

> ISO 9899/1999 says: "Any pointer may be converted to an integer type. [...]
>          The result need not be in the range of values of any integer type."

... and it sure as hell does *NOT* say that controlling expression of
if statement is converted to an integer type.  For pointers of for anything
else.  if (v) is the same as if (v != 0) [6.8.4.1p2], and if v is a pointer,
0 in that comparison becomes a null pointer constant [6.5.9p5].
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