[cfe-dev] clang vs. gcc

[Neil Booth]

Filipe Cabecinhas wrote:-

> Hi,
> 
> clang doesn't compile the following code:
> ---------------------------
> [filcab at farnsworth ~] $ cat a.c
> #include <stdio.h>
> 
> extern void a;
> 
> int main ()
> {
>    printf("%p\n", &a);
>    return 0;
> }
> ---------------------------
> 
> [filcab at farnsworth ~] $ gcc -c a.c
> [filcab at farnsworth ~] $ clang -c a.c
> a.c:7:18: error: address expression must be an lvalue or a function 
> designator
>    printf("%p\n", &a);
>                   ^~
> 1 diagnostic generated.
> 
> Should I file a bug report or is it intended? If you want to know, it's 
> from valgrind's source code. The symbol acts as a marker and is defined 
> in a .S file.

If you declare it instead as

	extern const void a;

the code is valid C.

Neil.