Debug derived when not working for opaque type

[usamec]

Input C/C++ Header

class A {
  long long b;
  long long b2;                
  long long b3;                                                                                          
  long long b4;                                                                                          
  long long b5; 
  long long b6;
  long long b7;                                                                                          
  long long b8;                                                                                          
  long long bb;                                                                                          
  long long bb2;
  long long bb3;                                                                                         
  long long bb4;
  long long bb5;
  long long bb6;                                                                                         
  long long bb7;
  long long bb8;
  long long c;                                                                                           
  long long c2;
  long long c3;                                                                                          
  long long c4;
  long long c5;                                                                                          
  long long c6;
  long long c7;                                                                                          
  long long c8;
  long long cc;                                                                                          
  long long cc2;                                                                                         
  long long cc3;                                                                                         
  long long cc4;
  long long cc5;
  long long cc6;                                                                                         
  long long cc7;                                                                                         
  long long cc8;
  long long dd2;
  long long dd3;
  long long dd4;
  long long dd5;
  long long dd6;                                                                                         
  long long dd7;                                                                                         
  long long dd8;
}; 

Bindgen Invocation

$ bindgen test_bing3.hpp -o src/bindings.rs --opaque-type "A" -- -x c++

Actual Results

#[repr(C)]
#[derive(Debug)]
pub struct A {
    pub _bindgen_opaque_blob: [u64; 39usize],
}
#[test]
fn bindgen_test_layout_A() {
    assert_eq!(::std::mem::size_of::<A>() , 312usize , concat ! (
               "Size of: " , stringify ! ( A ) ));
    assert_eq! (::std::mem::align_of::<A>() , 8usize , concat ! (
                "Alignment of " , stringify ! ( A ) ));
}

and/or

error[E0277]: the trait bound `[u64; 39]: std::fmt::Debug` is not satisfied
 --> src/bindings.rs:6:5
  |
6 |     pub _bindgen_opaque_blob: [u64; 39usize],
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `[u64; 39]` cannot be formatted using `:?`; if it is defined in your crate, add `#[derive(Debug)]` or manually implement it
  |
  = help: the trait `std::fmt::Debug` is not implemented for `[u64; 39]`
  = note: required because of the requirements on the impl of `std::fmt::Debug` for `&[u64; 39]`
  = note: required for the cast to the object type `std::fmt::Debug`

Expected Results

Debug trait is not used.

[fitzgen]

What version of bindgen are you using? I thought we fixed exactly this bug in the last release, but maybe the fix is stuck on master and isn't released yet...

[pepyakin]

Yep, it doesn't reproduce on the master,

/* automatically generated by rust-bindgen */

#[repr(C)]
pub struct A {
    pub _bindgen_opaque_blob: [u64; 39usize],
}
#[test]
fn bindgen_test_layout_A() {
    assert_eq!(
        ::std::mem::size_of::<A>(),
        312usize,
        concat!("Size of: ", stringify!(A))
    );
    assert_eq!(
        ::std::mem::align_of::<A>(),
        8usize,
        concat!("Alignment of ", stringify!(A))
    );
}

[fitzgen]

Ok, let's close this after we cut a new release.

All that is blocking that is #977