Eric Blake wrote:
> I argue that NetBSD's definition of NULL is thus buggy
It appears to be compliant with ISO C99. This standard requires
6.5.3 and Annex A.2.1
Syntax
unary-expression:
...
sizeof unary-expression
sizeof ( type-name )
cast-expression:
unary-expression
( type-name ) cast-expression
So, when you apply 'sizeof' to an expression, it must be a unary-expression.
But '(void*)0' is a cast-expression, not a unary-expression.
7.17.(3) "NULL which expands to an implementation-defined null pointer constant"
This does not require that the expansion is a unary-expression.
Regarding POSIX, with XSH 2.1.2.(1), you are probably right.
> we should add gnulib check and config.h workaround for it.
The definition of NULL is a particularly thorny area, because so many headers
use it and so many headers define it. I don't think it's worth the trouble -
it's easier to accept the fact that it's more reliable to parenthesize the
argument of sizeof when that argument is a macro invocation.
Bruno
