How to check that a member function is generated by compiler?

[Paul Backus]

On Friday, 25 February 2022 at 14:25:22 UTC, Andrey Zherikov 
wrote:
>
> Another interesting observation - is there any explanation why 
> `typeof` returns different results for generated `opAssign`?
[...]
>
> If I move `foreach` loop into a function (e.g. `main`) then the 
> first pragma prints the same as the others.

It sounds like this is probably an inconsistency in `.stringof`, 
not `typeof`. I couldn't say what causes it, but it's not the 
first time I've seen `.stringof` give inconsistent results. 
(E.g., https://issues.dlang.org/show_bug.cgi?id=18269)