Re: GCC headers and DJGPP port (OT)

[Oleg Zabluda <zabluda at mindspring dot com>]

On Thu, 28 Aug 2036, Linus Torvalds wrote:
> 
> Off-topic: why is it exactly that C++ doesn't like the "((void *)0)"
> thing, which as far as I can tell has all the same advantages? Was it
> purely a "stupid standard" issue, or is there some actual real deeper
> reason for it?
> 
> That was one of my pet peeves about C++: I always considered the
> historical "#define NULL 0" to be complete braindamage due to lack of
> even the simplest kind of type-checking (and matching to a pointer type
> is just one small portion of that type-checking - getting sane and
> appropriate warnings is quite important). 

For the purpose of this discussion, it's enough to know that a "null pointer
constant" can be used to initialize or assign to a pointer, despite the fact
that their types do not match.

In both C and C++ ((int)0) was always a "null pointer constant". C additionally
allowed ((void*)0) to be a "null pointer constant". It was more acceptable in C
then in C++ because of the weaker typesystem. In C++ there is no implicit
conversion from void* to pointers-to-object, say int*.

Still, it's not a showcase of elegance. For example, in ANSI C there is
no conversion, implicit or otherwise, from void* to pointer-to-function. 

In C++ inelegance would be even worse, because there are two more incompatible
pointer types: pointer-to-member-variable and pointer-to-member-function.

Oleg.