[Issue 23404] CTFE evaluation is unecessary when passing function return type as aliased template argument

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=23404

--- Comment #2 from Luís Ferreira <contact at lsferreira.net> ---
(In reply to ag0aep6g from comment #1)
> You're not passing `foo`'s return *type* to `weird`. You're trying to pass
> its return *value*. For that, the function must go through CTFE.
> 
> As far as I can see, there is no bug here. Closing as invalid.

Well I thought that this was possible:

```
void bar();

int foo()()
{
    bar();
    return 1;
}

void weird(alias func)() {}

void main()
{
    alias func = foo();
}
```

But it fails too. To be clear, I'm not expecting it to be the return type but
the template instance, but there's nothing to be CTFEable here.

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