Bindings fail to compile with "the name ... is defined multiple times" and "cycle detected when computing type of ..."

[boydjohnson]

c++ header

template <typename> struct a { typedef int b; };
template <typename = a<int>> class c;
template <typename e> class c {
  typedef typename e::b b;
  c &d(long, b);
};
template <> c<> &c<>::d(long, b);

bindgen test-case-4.hpp -- -x c++ produces

#[repr(C)]
#[derive(Debug, Copy, Clone)]
pub struct a {
    pub _address: u8,
}
pub type a_b = ::std::os::raw::c_int;
#[repr(C)]
#[derive(Debug, Copy, Clone)]
pub struct c {
    pub _address: u8,
}
pub type c_b = [u8; 0usize];
pub type b = b;
pub type b = ::std::os::raw::c_int;

`rustc --crate-type lib bindings.rs``` produces

error[E0428]: the name `b` is defined multiple times
  --> bindings.rs:16:1
   |
15 | pub type b = b;
   | --------------- previous definition of the type `b` here
16 | pub type b = ::std::os::raw::c_int;
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `b` redefined here
   |
   = note: `b` must be defined only once in the type namespace of this module

error[E0391]: cycle detected when computing type of `b`
  --> bindings.rs:15:14
   |
15 | pub type b = b;
   |              ^
   |
   = note: ...which again requires computing type of `b`, completing the cycle
note: cycle used when collecting item types in top-level module
  --> bindings.rs:3:1
   |
3  | / #[repr(C)]
4  | | #[derive(Debug, Copy, Clone)]
5  | | pub struct a {
6  | |     pub _address: u8,
...  |
15 | | pub type b = b;
16 | | pub type b = ::std::os::raw::c_int;
   | |___________________________________^

This might be template specialization (my c++ is really poor) and so not expected to work. I wish bindgen would warn me that that was taking place instead of producing bindings that can't compile.

[emilio]

Looks related to #1918 in the sense that we don't deal extremely well with templates that are very recursive. Generally we'd need more clang introspection for that I'd think.