Re: [Libclc-developers] Some more comments to the current CVS tree

[regis <re...@in...>]

Jan Engelhardt wrote:
> 
> Hi there,
> 
> whilst looking through the current CVS snapshots, I stumbled over these issues:
> 
> doc/string/clc_stralloc.txt:
>   char *s = clc_stralloc("foo", "bar", (char *)0);
> 
>   Can't we assume that NULL is (something casted) 0? Yet,
>   NULL is defined as (void *)0, but that is not a big difference
>   to (char *)0. Even (int *)0 would work, wouldn't it?

No.

(char *)0 is an argument that is part part of the ellipsis
in the variadic function. So, there is no type conversion:
an arg of the exact type muist be pass, therefore the cast.
If a bare 0 is passed, then an int is passed, and
1) its sizeof may differ from the expected  pointer
2) its zero-representation may not be the repr. of 
   the null pointer for this type. An implmentation may
   decide e.g. that the hex value 0xDEADBEEF is the repr.
   of a null pointer.

And the repr. of two null pointers for two different types 
may differ.