• d-bugmail puremagic.com (37/37) Nov 18 2021 https://issues.dlang.org/show_bug.cgi?id=22526

d-bugmail puremagic.com writes:

https://issues.dlang.org/show_bug.cgi?id=22526

          Issue ID: 22526
           Summary: Strange type error for function pointer that
                    references its own container
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody puremagic.com
          Reporter: andy.pj.hanson gmail.com

```
alias Fn(T) = void function(FnContainer!T);

void fn(T)(FnContainer!T) {}

struct FnContainer(T) {
        Fn!T* fn;
}

void main() {
        Fn!int fnInt = &fn!int;
        Fn!string fnString = &fn!string;
        FnContainer!string a = FnContainer!string(&fnString);
}
```

When I run `dmd a.d`, it fails with:
```
a.d(12): Error: cannot implicitly convert expression `& fnString` of type `void
function(FnContainer!string)*` to `void function(FnContainer!int)*`
```

This code ought to compile since I explicitly requested a `FnContainer!string`.
It is incorrectly expecting the parameter to be a `Fn!int*`.

There is no error if the unused variable `fnInt` is removed.
There is also no error if the container has `Fn!T` instead of `Fn!T*`. (In my
case I actually want a function pointer pointer.)

--