Implement standard traits for NativePointer

[fabianfreyer]

Implement Copy, Clone, Hash, and Eq for NativePointers. Additionally, make NativePointer #[repr(transparent)], so it can be used in FFI just like the underlying *mut c_void.

[meme]

In many ways, the intention was to not derive these traits so that it could not be interchanged with a *mut c_void.

Is there a specific helper function on NativePointer that addresses your issue instead? What is the ergonomics issue you are having with NativePointer?

[fabianfreyer]

The ergonomics I'm missing are:

• Comparing native pointers, e.g. to check whether a given NativePointer equals a specific other one in a transformer.
• Using native pointers as keys in a HashMap / HashSet
• Ownership issues e.g. when passing NativePointer into a closure, because there is no way to clone or copy a NativePointer, and repeating the code to get the corresponding pointer, e.g. doing symbol lookups for every instance I need would add significant overhead. Currently, my code is full of calling NativePointer(other.0) because *mut c_void implements Copy.

I'm not really sure what is gained by not deriving these traits.

The #[repr(transparent)] is useful for std::mem::transmute, e.g. to be able to transmute to function pointers.

[fabianfreyer]

Thank you!