Cannot check function address

[Steven Schveighoffer]

On 5/24/22 10:06 PM, frame wrote:
> 
> Sorry, this was not affront, it was meant as my POV that you may have 
> problems to get my problem because I have (as usually) forgot to make 
> this more visible that some code was truncated.

OK, sorry to read into that ;)

> I tried your suggestion, as replied to Adam - the symbol is unique and 
> it shows that correct location. It's not different from the error message.

Just to be pedantic, you tried that call in the *exact place* the assert 
is failing to compile? D can be weird/surprising about name lookups.

> 
> However, this error has nothing to do with `assert()`. In fact the 
> compiler allows nothing than invocation or this error will be triggered. 
> Even that fails:

The compiler is treating `fun` not as a function pointer, but as a 
function. However, the type looks correct to me. I tried a simple 
example on run.dlang.io, even with multiple modules, and seems to work 
as expected.

> 
> ```d
> // same error:
> auto test = cast(void*)fun;
> ```
> 

try:

pragma(msg, typeof(fun));

If I do:

```d
extern(C) void foo(string) {}

pragma(msg, typeof(foo));
pragma(msg, typeof(&foo));
```

I get:

extern (C) void(string param)
extern (C) void function(string param)

The first is a function (yes, they have a type), and the latter is a 
function pointer.

So that might give a clue whether the compiler thinks `fun` is a 
function or a function pointer. D should *never* call a function pointer 
without parentheses.

If you get the latter, yet your assert fails, then that is most 
certainly a compiler bug. Again, important that you do this in the exact 
place the assert fails to ensure the same name lookup situation.

-Steve