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

[Andrey Zherikov]

On Friday, 25 February 2022 at 05:25:14 UTC, Ali Çehreli wrote:
> On 2/24/22 20:44, Andrey Zherikov wrote:
>
>> How can I check that `opAssign` is generated by compiler and 
>> doesn't exist in the original code?
>
> I think this one:
>
>   https://dlang.org/phobos/std_traits.html#hasElaborateAssign
>
> Ali

This take a struct as an argument, not a member, so I need to do 
`if(sym == "opAssign")`. I gave this another thought and checking 
the symbol against `"opAssign"` would be good enough for my use 
case.

Another interesting observation - is there any explanation why 
`typeof` returns different results for generated `opAssign`?
```d
import std.sumtype: SumType;

struct A
{
     SumType!int b;
}

static foreach(sym; __traits(allMembers, A))
{
     // ref A(A p) return,opAssign
     pragma(msg,
               typeof(__traits(getMember, A, 
sym)).stringof,",",sym);

     // true,pure nothrow @nogc ref @safe A(A p) return,opAssign

     pragma(msg,
            is(typeof(__traits(getMember, A, sym)) == 
function),",",
               typeof(__traits(getMember, A, 
sym)).stringof,",",sym);

	// pure nothrow @nogc ref @safe A(A p) return,opAssign
     pragma(msg,
               typeof(__traits(getMember, A, 
sym)).stringof,",",sym);
}
```

If I move `foreach` loop into a function (e.g. `main`) then the 
first pragma prints the same as the others.