stylo bindings busted on UniquePtr

[bholley]

I bisected this down to #281.

The broken line in question comes from UniquePtr.h:

pub type mozilla_UniquePtr_Pointer = typename detail::PointerType<T, DeleterType>::Type;

CC @fitzgen @emilio @heycam @Manishearth @upsuper

[upsuper]

The following code is enough to reproduce this bug:

namespace detail {
  template<typename T>
  struct PointerType {
    typedef T* Type;
  };
}
template<typename T>
class UniquePtr {
  typedef typename detail::PointerType<T>::Type Pointer;
};

rust-bindgen generates:

#[repr(C)]
#[derive(Debug, Copy, Clone)]
pub struct detail_PointerType<T> {
    pub _address: u8,
    pub _phantom_0: ::std::marker::PhantomData<T>,
}
pub type detail_PointerType_Type<T> = *mut T;
#[repr(C)]
#[derive(Debug, Copy, Clone)]
pub struct UniquePtr<T> {
    pub _address: u8,
    pub _phantom_0: ::std::marker::PhantomData<T>,
}
pub type UniquePtr_Pointer = typename detail::PointerType<T>::Type;

[upsuper]

Looks like detail::PointerType<T>::Type is an unexposed type. We probably need to skip it.

The issue here is not limited to the wrong type. We would also need to handle the new namespace prefix.

[upsuper]

I guess if #287 can be fixed, we can just enable namespaces, and insert raw lines like

pub use root::*;
pub use root::mozilla::*;

so that the majority of existing code wouldn't need any update.

[emilio]

Yeah, to be clear this is a bug that was exposed by #281, not created by it. Before #281 the two items had the same name so we only generated the first one. Looking into this.

Also, good catch with #287, should be easy-ish to fix.

[emilio]

Should be partially fixed with #288. See that pull request for discussion. In any case shouldn't generate invalid output now.