Puzzled by this behavior

[Ola Fosheim Grøstad]

On Tuesday, 31 May 2022 at 20:47:36 UTC, Steven Schveighoffer 
wrote:
> So I assume it's similar to declaring functions, but I don't 
> know the reason it allows this for function prototypes at the 
> module level.

Maybe he didn't think about mutual recursion.

Anyway, this is legal in C++:

```
extern int x;
extern int x;
void f();
void f();
void f(){ x=0;}
int x = 1;
```