[cfe-dev] #define behavior

[Neil Booth]

Bill Wendling wrote:-

> Here's an interesting question that occurred in one of the OCCC  
> entries that I was compiling with clang. This program:

I would hope OCCC entries would be valid C.

> $ cat d.c
> #define x =
> 
> int foo(int *k) {
>    return *k *x 37;
> }
> 
> Generates this:
> 
> $ clang -ast-print d.c -triple=i686-apple-darwin9
> typedef char *__builtin_va_list;
> d.c:4:14: error: expected expression
>    return *k *x 37;
>               ^
> 
> int foo(int *k) {
> }
> 
> 1 diagnostic generated.
> 
> GCC also balks at this. It appears that there's a space being  
> inserted after the "*" and before the "=" that "x" becomes. Is this  
> expected?

Standard C works on tokens, not text, so the code is invalid as
* and = are two separate tokens.

Neil.