Missing class methods bindings when target is i686-pc-windows-gnu

Input C/C++ Header

struct Vec2 {
  float x, y;
  void reset();
};

Bindgen Invocation

$ bindgen test.hpp -- -target i686-pc-windows-gnu

Actual Results

/* automatically generated by rust-bindgen */

#[repr(C)]
#[derive(Debug, Copy, Clone)]
pub struct Vec2 {
    pub x: f32,
    pub y: f32,
}
#[test]
fn bindgen_test_layout_Vec2() {
    assert_eq!(
        ::std::mem::size_of::<Vec2>(),
        8usize,
        concat!("Size of: ", stringify!(Vec2))
    );
    assert_eq!(
        ::std::mem::align_of::<Vec2>(),
        4usize,
        concat!("Alignment of ", stringify!(Vec2))
    );
    assert_eq!(
        unsafe { &(*(::std::ptr::null::<Vec2>())).x as *const _ as usize },
        0usize,
        concat!("Offset of field: ", stringify!(Vec2), "::", stringify!(x))
    );
    assert_eq!(
        unsafe { &(*(::std::ptr::null::<Vec2>())).y as *const _ as usize },
        4usize,
        concat!("Offset of field: ", stringify!(Vec2), "::", stringify!(y))
    );
}

Expected Results

However when target is x86_64 it works as expected:

$ bindgen test.hpp -- -target x86_64-pc-windows-gnu

The result is:

/* automatically generated by rust-bindgen */

#[repr(C)]
#[derive(Debug, Copy, Clone)]
pub struct Vec2 {
    pub x: f32,
    pub y: f32,
}
#[test]
fn bindgen_test_layout_Vec2() {
    assert_eq!(
        ::std::mem::size_of::<Vec2>(),
        8usize,
        concat!("Size of: ", stringify!(Vec2))
    );
    assert_eq!(
        ::std::mem::align_of::<Vec2>(),
        4usize,
        concat!("Alignment of ", stringify!(Vec2))
    );
    assert_eq!(
        unsafe { &(*(::std::ptr::null::<Vec2>())).x as *const _ as usize },
        0usize,
        concat!("Offset of field: ", stringify!(Vec2), "::", stringify!(x))
    );
    assert_eq!(
        unsafe { &(*(::std::ptr::null::<Vec2>())).y as *const _ as usize },
        4usize,
        concat!("Offset of field: ", stringify!(Vec2), "::", stringify!(y))
    );
}
extern "C" {
    #[link_name = "\u{1}_ZN4Vec25resetEv"]
    pub fn Vec2_reset(this: *mut Vec2);
}
impl Vec2 {
    #[inline]
    pub unsafe fn reset(&mut self) {
        Vec2_reset(self)
    }
}

I assume the both results should looks similar but this isn't so.

This issue looks like a #751, but adding -fvisibility=default doesn't help.
Also I tried to set appropriate sysroot to clang (using -isysroot) but It also doesn't help.

Reproduce the discrepancy with the test.hpp header and the bindgen commands for i686-pc-windows-gnu and x86_64-pc-windows-gnu. Trace target-specific handling of C++ class methods and symbol generation; done means the i686 output includes the reset binding consistently with the x86_64 output.