Feature request: generate types for api functions

[kgv]

Motivation

Generate types for api functions will be useful for dynamic exploration. For example when using GetModuleHandleW and GetProcAddress. GetProcAddress return FARPROC which we need to transmute into a function. To do this, we need to know the type of the function.

Drawbacks

Perhaps there is some way to get function pointer type from function pointer. But I don't know this.

Rationale and alternatives

A similar macro solves the problem, but not for the case with static variable. For statics, you must explicitly specify the type.

pub macro export {
    ($module:expr, $target:ty) => {
        GetProcAddress($module, stringify!($target)).map(|source| transmute::<_, $target>(source))
    },
    ($module:expr, $target:ident) => {
        GetProcAddress($module, stringify!($target)).map(|source| {
            #[allow(unused_assignments)]
            let mut target = &$target;
            target = transmute(source);
            *target
        })
    },
}

Additional context

See func-types feature in ntapi (Implementation).

[kennykerr]

Yep, I'd like to be able to generate these but a little concerned about the explosion in crate size. Will think about it some more.

[Zerowalker]

out of interest, what size differences are we talking about, 20%, 100%, 500%?

[kennykerr]

Code size, build time, maintainability. All factors to consider. There are a lot of API functions in the windows crate. I just have to try it and see how practical it is.

[kennykerr]

While this would be convenient for experimenting, I don't think there is enough demand for such a capability to warrant including all the extra generated code needed to make it happen.

[mzdk100]

I want to know how to convert the FARPROC type obtained from GetProcAddress to the HOOKPROC type.