rust-lang / rust-lang/rust-bindgen
Bindgen fails to generate constants if `#define`s are out of order
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Description
Input C/C++ Header
#define A B
#define B 1
Bindgen Invocation
bindgen input.h
Actual Results
/* automatically generated by rust-bindgen 0.66.1 */
pub const B: u32 = 1;
Expected Results
I expected
pub const A: u32 = 1;
pub const B: u32 = 1;
Both gcc and clang accept these kind of "out of order" definitions (as counter-intuitive as it is), and the linux kernel makes use of this in kvm.h, which is how we discovered this issue in https://github.com/rust-vmm/kvm-bindings/pull/89
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by running the reported bindgen input.h reproduction with the out-of-order #defines and trace how constants are generated. Done means the generated Rust output includes both A and B with the value 1, rather than omitting A.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- c, rust
- Domain
- tooling
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100