mixin template bug with opBinary?

[Adam D Ruppe]

On Friday, 22 July 2022 at 12:33:37 UTC, Anthony Quizon wrote:
> Is this a bug or am I doing something wrong?

I think this is a bug. The compiler must not take well to this 
pattern, maybe the assoc array template argument, but idk. It 
looks like the first type used gets cached and reused even if it 
is supposed to change.

I vaguely recall seeing this before.... but yeah smells buggy 
anyway.


An alternative you might consider is dropping some of the type 
and using typeof(this):

```
module foo;

mixin template opBi(
     alias f0
) {
     static foreach (k, f; f0) { typeof(this) opBinary(string op:
     k)(typeof(this) r) { return f(this, r); } }
}

struct A {
     mixin opBi!(
         [ "+": (A a, A b) => a],
     );
}

struct B {
     mixin opBi!(
         [ "+": (B a, B b) => a],
     );
}
```

That sidesteps the bug though it just trusts you pass the right 
type to `f0`.