Wrong type size on packed enum

I am working on a rust wrapper for a c library and there is one place I have to go and manually edit the bindgen file after generation. The problem is a packed enum that is then used in a struct. Bindgen is tagging the enum with #[repr(i32)], but because it is a packed enum, it should be #[repr(u8)] or similar. This causes the struct which uses the enum to be too large on the rust side and cause a segfault when attempting to access the enum member of the struct.

compiling on windows

a simplified version of the c file:

typedef __pragma(pack(push, 1)) enum __pragma(pack(pop)) {
    a,
    b,
    c,
} aaa;

typedef struct {
    /* other fields */
    aaa field;
} bbb;

I'm using rustified enums which work really well for my use case. after generation, I have to manually change the bindgen output file enum tag from repr(i32) to repr(u8) and I have to change the size of the struct from 88usize to 80usize and change the offset of the field from 80usize to 78usize

Start by reproducing the simplified packed-enum C case on Windows with rustified enums and inspect the generated bindgen file. Compare the enum representation, struct size, and field offset with the C layout; done means the generated Rust layout no longer requires manual edits and avoids the reported mismatch.