| Bjorn Reese 2007-05-26, 7:21 am |
| Bjorn Reese wrote:
> That is a good question. According to my reading of C99, char and float
> are not compatible [6.2.7] even after default argument promotion, so
> char * and float * are not compatible either [6.7.5.1/2, 6.2.5/27].
> Getting an incompatible pointer with va_arg() invokes undefined behavior
> [6.5.2.2/6].
>
> Another way to look at it is that void * and char * are required to have
> the same representation and alignment, but char * and float * are not
> [6.2.5/17].
I should add that by the time I wrote the above, I was not aware that
SUS has an added requirement for va_arg() to handle all pointer types
as compatible. So, if execl() is implemented with va_arg() then there is
no difference between using "(char *)0" or "(float *)0" as the last
argument.
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