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

[katyo]

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.

[katyo]

Hmm,
The log looks strange:

...
[2020-03-02T08:31:33Z DEBUG bindgen::codegen] <Item as CodeGenerator>::codegen: self = Item { id: ItemId(11), local_id: LazyCell { inner: UnsafeCell }, next_child_local_id: Cell { value: 1 }, canonical_name: LazyCell { inner: UnsafeCell }, path_for_whitelisting: LazyCell { inner: UnsafeCell }, comment: None, annotations: Annotations { opaque: false, hide: false, use_instead_of: None, disallow_copy: false, private_fields: None, accessor_kind: None, constify_enum_variant: false, derives: [] }, parent_id: ItemId(1), kind: Function(Function { name: "reset", mangled_name: Some("__ZN4Vec25resetEv"), signature: TypeId(ItemId(6)), comment: None, kind: Method(Normal), linkage: External }) }
[2020-03-02T08:31:33Z DEBUG bindgen::codegen] <Function as CodeGenerator>::codegen: item = Item { id: ItemId(11), local_id: LazyCell { inner: UnsafeCell }, next_child_local_id: Cell { value: 1 }, canonical_name: LazyCell { inner: UnsafeCell }, path_for_whitelisting: LazyCell { inner: UnsafeCell }, comment: None, annotations: Annotations { opaque: false, hide: false, use_instead_of: None, disallow_copy: false, private_fields: None, accessor_kind: None, constify_enum_variant: false, derives: [] }, parent_id: ItemId(1), kind: Function(Function { name: "reset", mangled_name: Some("__ZN4Vec25resetEv"), signature: TypeId(ItemId(6)), comment: None, kind: Method(Normal), linkage: External }) }
[2020-03-02T08:31:33Z WARN  bindgen::codegen] Skipping function with thiscall ABI that isn't supported by the configured Rust target
...

Which means "isn't supported by the configured Rust target"?

UPD:
It seems "thiscall" still unstable rust feature...

[katyo]

As wiki says "for the GCC compiler, thiscall is almost identical to cdecl". Are that means this is unexpected behavior?

[emilio]

thiscall is generated if rustc supports it. It is unstable still per rust-lang/rust#42202.

You can generate it if you build with rust-target=nightly. That being said if the ABI is just cdecl in some targets we may want to make the checks here and in similar places more nuanced.