Incorrect codegen for clang block with single arg

[benw]

Input C/C++ Header

void foo(void (^callback)(unsigned char));

Bindgen Invocation

$ bindgen --generate-block --block-extern-crate input.h

Actual Results

extern "C" {
    #[link_name = "\u{1}_foo"]
    pub fn foo(callback: _bindgen_ty_id_6);
}
pub type _bindgen_ty_id_6 =
    *const ::block::Block<(::std::os::raw::c_uchar), ()>;

The problem is in the last line: the Block's arg type should be the single-element tuple (c_uchar,) but it is missing the comma. This non-tuple type is incompatible with the BlockArguments trait.

Expected Results

extern "C" {
    #[link_name = "\u{1}_foo"]
    pub fn foo(callback: _bindgen_ty_id_6);
}
pub type _bindgen_ty_id_6 =
    *const ::block::Block<(::std::os::raw::c_uchar,), ()>;

Impact

Trying to invoke this function:

unsafe fn bar(callback: *const Block<(u8,), ()>) {
    foo(callback);
}

leads to error:

error[E0308]: mismatched types
 --> src/lib.rs:7:9
  |
7 |     foo(callback);
  |         ^^^^^^^^ expected u8, found tuple
  |
  = note: expected type `*const ffi::block::Block<u8, ()>`
             found type `*const ffi::block::Block<(u8,), ()>`

[emilio]

Fixed by #1519. Thanks @flier!