c_void seems problematic

[tomjakubowski]

From the docs: http://doc.rust-lang.org/libc/types/common/c95/enum.c_void.html

For LLVM to recognize the void pointer type and by extension functions like malloc(), we need to have it represented as i8* in LLVM bitcode. The enum used here ensures this and prevents misuse of the "raw" type by only having private variants.

Since Rust lost private variants months ago, perhaps another approach should be considered.

[tomjakubowski]

It could probably be rewritten as:

#[repr(u8)]
enum c_void_inner {
    __variant1,
    __variant2
}

#[repr(u8)]
pub struct c_void(c_void_inner);

But I don't know if this will actually be treated the same by LLVM.

[steveklabnik]

moved to rust-lang/libc#48