Miguel Ojeda 8cbc95f983 rust: workaround bindgen issue with forward references to enum types ... `bindgen` currently generates the wrong type for an `enum` when there is a forward reference to it. For instance: enum E; enum E { A }; generates: pub const E_A: E = 0; pub type E = i32; instead of the expected: pub const E_A: E = 0; pub type E = ffi::c_uint; The issue was reported to upstream `bindgen` [1]. Now, both GCC and Clang support silently these forward references to `enum` types, unless `-Wpedantic` is passed, and it turns out that some headers in the kernel depend on them. Thus, depending on how the headers are included, which in turn may depend on the kernel configuration or the architecture, we may get a different type on the Rust side for a given C `enum`. That can be quite confusing, to say the least, especially since developers may only notice issues when building for other architectures like in [2]. In particular, they may end up forcing a cast and adding an `#[allow(clippy::unnecessary_cast)]` like it was done in commit 94e05a66ea ("rust: hrtimer: allow timer restart from timer handler"), which isn't great. Instead, let's have a section at the top of our `bindings_helper.h` that `#include`s the headers with the affected types -- hopefully there are not many cases and there is a single ordering that covers all cases. This allows us to remove the cast and the `#[allow]`, thus keeping the correct code in the source files. When the issue gets resolved in upstream `bindgen` (and we update our minimum `bindgen` version), we can easily remove this section at the top. Link: https://github.com/rust-lang/rust-bindgen/issues/3179 [1] Link: https://lore.kernel.org/rust-for-linux/87tt7md1s6.fsf@kernel.org/ [2] Acked-by: Andreas Hindborg <a.hindborg@kernel.org> Link: https://lore.kernel.org/r/20250325184309.97170-1-ojeda@kernel.org [ Added extra paragraph on the comment to clarify that the workaround may not be possible in some cases. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>		2025-05-22 15:39:16 +02:00
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hrtimer	rust: hrtimer: Add Ktime temporarily	2025-04-29 15:31:07 +02:00
hrtimer.rs	rust: workaround bindgen issue with forward references to enum types	2025-05-22 15:39:16 +02:00