This updates rust-bindgen to version 0.69.4 which includes the patch 199bee441ad0: "try to avoid #[repr(packed)] when align is needed". With this patch, bindgen generates code that is both ABI-correct and can be compiled by rustc, for 3 bcachefs types:
- bkey - bch_extent_crc32 - bch_extent_ptr This allows us to remove the custom treatment for these three types. Signed-off-by: Thomas Bertschinger <[email protected]> --- Cargo.lock | 21 ++++++++++++--------- bch_bindgen/Cargo.toml | 2 +- bch_bindgen/build.rs | 43 +++++++++--------------------------------- 3 files changed, 22 insertions(+), 44 deletions(-) diff --git a/Cargo.lock b/Cargo.lock index bcbdbc5..9987974 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -119,17 +119,17 @@ dependencies = [ [[package]] name = "bindgen" -version = "0.69.2" +version = "0.69.4" source = "registry+https://github.com/rust-lang/crates.io-index"; -checksum = "a4c69fae65a523209d34240b60abe0c42d33d1045d445c0839d8a4894a736e2d" +checksum = "a00dc851838a2120612785d195287475a3ac45514741da670b735818822129a0" dependencies = [ "bitflags 2.4.2", "cexpr", "clang-sys", + "itertools", "lazy_static", "lazycell", "log", - "peeking_take_while", "prettyplease", "proc-macro2", "quote", @@ -332,6 +332,15 @@ dependencies = [ "windows-sys 0.52.0", ] +[[package]] +name = "itertools" +version = "0.12.1" +source = "registry+https://github.com/rust-lang/crates.io-index"; +checksum = "ba291022dbbd398a455acf126c1e341954079855bc60dfdda641363bd6922569" +dependencies = [ + "either", +] + [[package]] name = "lazy_static" version = "1.4.0" @@ -425,12 +434,6 @@ version = "1.0.14" source = "registry+https://github.com/rust-lang/crates.io-index"; checksum = "de3145af08024dea9fa9914f381a17b8fc6034dfb00f3a84013f7ff43f29ed4c" -[[package]] -name = "peeking_take_while" -version = "0.1.2" -source = "registry+https://github.com/rust-lang/crates.io-index"; -checksum = "19b17cddbe7ec3f8bc800887bab5e717348c95ea2ca0b1bf0837fb964dc67099" - [[package]] name = "pkg-config" version = "0.3.29" diff --git a/bch_bindgen/Cargo.toml b/bch_bindgen/Cargo.toml index fcc4668..63be4f3 100644 --- a/bch_bindgen/Cargo.toml +++ b/bch_bindgen/Cargo.toml @@ -19,4 +19,4 @@ paste = "1.0.11" [build-dependencies] pkg-config = "0.3" -bindgen = "0.69.2" +bindgen = "0.69.4" diff --git a/bch_bindgen/build.rs b/bch_bindgen/build.rs index c9a90fc..1baa266 100644 --- a/bch_bindgen/build.rs +++ b/bch_bindgen/build.rs @@ -120,40 +120,15 @@ fn main() { .expect("Writing to output file failed for: `keyutils.rs`"); } -// rustc has a limitation where it does not allow structs to have both a "packed" and "align" -// attribute. This means that bindgen cannot copy all attributes from some C types, like struct -// bkey, that are both packed and aligned. +// rustc has a limitation where it does not allow structs with a "packed" attribute to contain a +// member with an "align(N)" attribute. There is one type in bcachefs with this issue: +// struct btree_node. // -// bindgen tries to handle this situation smartly and for many types it will only apply a -// "packed(N)" attribute if that is good enough. However, there are a few types where bindgen -// does end up generating both a packed(N) and align(N) attribute. These types can't be compiled -// by rustc. -// -// To work around this, we can remove either the "packed" or "align" attribute. It happens that -// for all the types with this problem in bcachefs, removing the "packed" attribute and keeping -// the "align" attribute results in a type with the correct ABI. -// -// This function applies that transformation to the following bcachefs types that need it: -// - bkey -// - bch_extent_crc32 -// - bch_extent_ptr -// - btree_node +// Luckily, it happens that this type does not need the "packed(N)" attribute in Rust to have the +// same ABI as C, so we can strip it off the bindgen output. fn packed_and_align_fix(bindings: std::string::String) -> std::string::String { - bindings - .replace( - "#[repr(C, packed(8))]\n#[repr(align(8))]\n#[derive(Debug, Default, Copy, Clone)]\npub struct bkey {", - "#[repr(C, align(8))]\n#[derive(Debug, Default, Copy, Clone)]\npub struct bkey {", - ) - .replace( - "#[repr(C, packed(8))]\n#[repr(align(8))]\n#[derive(Debug, Default, Copy, Clone)]\npub struct bch_extent_crc32 {", - "#[repr(C, align(8))]\n#[derive(Debug, Default, Copy, Clone)]\npub struct bch_extent_crc32 {", - ) - .replace( - "#[repr(C, packed(8))]\n#[repr(align(8))]\n#[derive(Debug, Default, Copy, Clone)]\npub struct bch_extent_ptr {", - "#[repr(C, align(8))]\n#[derive(Debug, Default, Copy, Clone)]\npub struct bch_extent_ptr {", - ) - .replace( - "#[repr(C, packed(8))]\npub struct btree_node {", - "#[repr(C, align(8))]\npub struct btree_node {", - ) + bindings.replace( + "#[repr(C, packed(8))]\npub struct btree_node {", + "#[repr(C, align(8))]\npub struct btree_node {", + ) } -- 2.43.0
