When used as function parameter types or function return types, Rust function pointer types map into the corresponding C++ types as follows:
| Rust | C++ |
|---|---|
extern "C" fn(i32) | std::type_identity_t<void(int32_t)>& |
Option<extern "C" fn(i32)> | Not supported |
In other scenarios Rust function pointer types map into the corresponding C++ types as follows:
| Rust | C++ |
|---|---|
extern "C" fn(i32) | std::type_identity_t<void(int32_t)>* |
Option<extern "C" fn(i32)> | Not supported |
TODO: Link to the not-yet-written references.md with a longer explanation why Rust references are sometimes bound to C++ references and sometimes to C++ pointers (C++ references can only be bound once; C++ temporaries).