Hello,

following two proposal got accepted for C++23:
static operator() P1169R4 <https://wg21.link/P1169R4>
static operator[] P2589R0 <https://wg21.link/P2589R0>
Thanks a lot to the authors and everyone involved!

I want to raise the idea of also allowing conversion functions to be static.

template<auto X>
struct ConvertsTo {
     static operator auto() { return X; }
};

I don't know, if code like this actually exists today and would benefit
from my proposed change.

Lambdas:
Conversion functions which would benefit from being static, are the ones
of stateless lambdas:

auto L = [](int a){ return a * a; };
int(*Fptr)(int) = L;

P1169R4#lambdas
<https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p1169r4.html#lambdas>
explains, that making the callable operator of a stateless lambda
implicitly static, is an API and ABI break. Therefore, you have to
explicitly request the callable operator to be static: [](int a) static
{ return a * a; };.
In such situations, we could make the conversion operator of a lambda
static, too.

The proposed wording (in my opinion) would be, to remove the adjective
"non-static" from https://eel.is/c++draft/class.conv.fct#2 and regarding
the lambda the wording of
https://eel.is/c++draft/expr.prim.lambda.closure#8 would need some small
adjustment.

In 2001, Scott Meyers opened
https://cplusplus.github.io/CWG/issues/296.html and asked about this
exact topic. The resolution at this time has been to explicitly prohibit
static conversion functions. What is our take on that today?

Kind regards,
Kilian