bindgen fails to correctly convert the ~0ul constant on i368 architecture

[Jakuje]

We have header files with the following definition, which should use the largest unsigned long value:

#define CK_UNAVAILABLE_INFORMATION ~0UL

These are different on 32b and 64b architectures (not our choice of types)

When bindgen processes this inptut, it generates the following line of rust code:

pub const CK_UNAVAILABLE_INFORMATION: CK_ULONG = 18446744073709551615;

which is obviously wrong as the rust compiler will very soon figure out:

 --> src/conformance/../pkcs11/bindings.rs:7:50
  |
7 | pub const CK_UNAVAILABLE_INFORMATION: CK_ULONG = 18446744073709551615;
  |                                                  ^^^^^^^^^^^^^^^^^^^^
  |
  = note: the literal `18446744073709551615` does not fit into the type `u32` whose range is `0..=4294967295`
  = note: `#[deny(overflowing_literals)]` on by default

This happens both with 0.69 and 0.70 versions.

[pvdrz]

any luck when using the --clang-macro-fallback option?

[Jakuje]

Interesting. When using CLI of the bindgen 0.70.1, it looks like I am getting different results than what we get from the crate invocation during build process. This looks ok regardless the use of --clang-macro-fallback:

<mock-chroot> sh-5.2# cat input.h 
#define CK_UNAVAILABLE_INFORMATION ~0UL

<mock-chroot> sh-5.2# bindgen input.h -o bindings.rs
Failed to run rustfmt: Internal rustfmt error (non-fatal, continuing)
<mock-chroot> sh-5.2# cat bindings.rs && echo
/* automatically generated by rust-bindgen 0.70.1 */

pub const CK_UNAVAILABLE_INFORMATION : i32 = - 1 ;

So it sounds like this is not caused by the bindgen defaults, but by one of our callbacks, which looks like coming into the way:

https://github.com/latchset/kryoptic/blob/9e11dca89e8df270420e5c42aa51e1528c6799b3/build.rs#L23-L27

When I try to change this callback to the internal ULong, I am getting again the wrong value:

7 | pub const CK_UNAVAILABLE_INFORMATION: ::std::os::raw::c_ulong = 18446744073709551615;

So I assume this is not an issue of the default bindgen behavior, but the callbacks.

Adding just the following (hopefully correctly):

     bindgen::Builder::default()
+        .clang_macro_fallback()

does not make a difference in the output.