Incorrect return type when using __stdcall

[programmerjake]

I'm using bindgen version 0.40

Input C/C++ Header

typedef void (__stdcall *void_fn)();
typedef void_fn (__stdcall *fn)(int id);

Bindgen Invocation

    let builder = bindgen::builder()
        .header_contents(
            "header.h",
            r#"
typedef void (__stdcall *void_fn)();
typedef void_fn (__stdcall *fn)(int id);
"#
        ).clang_arg("-target")
        .clang_arg("i686-pc-windows-msvc")
        .prepend_enum_name(false)
        .layout_tests(false)
        .constified_enum(".*");
    let code = builder
        .generate()
        .map_err(|_| io::Error::new(io::ErrorKind::Other, "generate() failed"))?
        .to_string();
    println!("{}", code);

Actual Results

/* automatically generated by rust-bindgen */

pub type void_fn = ::std::option::Option<unsafe extern "stdcall" fn()>;
pub type fn_ = ::std::option::Option<
    unsafe extern "stdcall" fn(
        id: ::std::os::raw::c_int
    ) -> ::std::option::Option<
        unsafe extern "stdcall" fn(id: ::std::os::raw::c_int, ...),
    >,
>;

Expected Results

pub type void_fn = ::std::option::Option<unsafe extern "stdcall" fn()>;
pub type fn_ = ::std::option::Option<
    unsafe extern "stdcall" fn(
        id: ::std::os::raw::c_int
    ) -> void_fn,
>;

I expect the return type of fn_ to have no arguments.

[emilio]

Huh, this is a fun one, thanks!

[emilio]

This is the hack added in #549 biting us back. #1403 should have a better fix.