diff options
| author | Benno Lossin <lossin@kernel.org> | 2025-05-23 16:51:02 +0200 |
|---|---|---|
| committer | Benno Lossin <lossin@kernel.org> | 2025-06-11 21:13:57 +0200 |
| commit | ec87ec35ca8bd61bfc1200224d332b4573b9dafa (patch) | |
| tree | 03b481f0cb9bef8216c02d2b801e197ebbe33a46 /rust/pin-init/src/lib.rs | |
| parent | 9f473538706b9fb5e82c9864b04089d35e4f93d5 (diff) | |
rust: pin-init: implement `ZeroableOption` for function pointers with up to 20 arguments
`Option<[unsafe] [extern "abi"] fn(...args...) -> ret>` is documented
[1] to also have the `None` variant equal all zeroes.
Link: https://doc.rust-lang.org/stable/std/option/index.html#representation [1]
Link: https://github.com/Rust-for-Linux/pin-init/pull/56/commits/b6c1ab4fb3699765f81ae512ecac5a2f032d8d51
Link: https://lore.kernel.org/all/20250523145125.523275-7-lossin@kernel.org
Signed-off-by: Benno Lossin <lossin@kernel.org>
Diffstat (limited to 'rust/pin-init/src/lib.rs')
| -rw-r--r-- | rust/pin-init/src/lib.rs | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/rust/pin-init/src/lib.rs b/rust/pin-init/src/lib.rs index a4656e7976c7..3e5fe84ae547 100644 --- a/rust/pin-init/src/lib.rs +++ b/rust/pin-init/src/lib.rs @@ -1662,6 +1662,22 @@ macro_rules! impl_tuple_zeroable { impl_tuple_zeroable!(A, B, C, D, E, F, G, H, I, J); +macro_rules! impl_fn_zeroable_option { + ([$($abi:literal),* $(,)?] $args:tt) => { + $(impl_fn_zeroable_option!({extern $abi} $args);)* + $(impl_fn_zeroable_option!({unsafe extern $abi} $args);)* + }; + ({$($prefix:tt)*} {$(,)?}) => {}; + ({$($prefix:tt)*} {$ret:ident, $($rest:ident),* $(,)?}) => { + // SAFETY: function pointers are part of the option layout optimization: + // <https://doc.rust-lang.org/stable/std/option/index.html#representation>. + unsafe impl<$ret, $($rest),*> ZeroableOption for $($prefix)* fn($($rest),*) -> $ret {} + impl_fn_zeroable_option!({$($prefix)*} {$($rest),*,}); + }; +} + +impl_fn_zeroable_option!(["Rust", "C"] { A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U }); + /// This trait allows creating an instance of `Self` which contains exactly one /// [structurally pinned value](https://doc.rust-lang.org/std/pin/index.html#projections-and-structural-pinning). /// |