linux/rust/macros/lib.rs

504 lines
17 KiB

rust: kunit: support KUnit-mapped `assert!` macros in `#[test]`s The KUnit `#[test]` support that landed recently is very basic and does not map the `assert*!` macros into KUnit like the doctests do, so they panic at the moment. Thus implement the custom mapping in a similar way to doctests, reusing the infrastructure there. In Rust 1.88.0, the `file()` method in `Span` may be stable [1]. However, it was changed recently (from `SourceFile`), so we need to do something different in previous versions. Thus create a helper for it and use it to get the path. With this, a failing test suite like: #[kunit_tests(my_test_suite)] mod tests { use super::*; #[test] fn my_first_test() { assert_eq!(42, 43); } #[test] fn my_second_test() { assert!(42 >= 43); } } will properly map back to KUnit, printing something like: [ 1.924325] KTAP version 1 [ 1.924421] # Subtest: my_test_suite [ 1.924506] # speed: normal [ 1.924525] 1..2 [ 1.926385] # my_first_test: ASSERTION FAILED at rust/kernel/lib.rs:251 [ 1.926385] Expected 42 == 43 to be true, but is false [ 1.928026] # my_first_test.speed: normal [ 1.928075] not ok 1 my_first_test [ 1.928723] # my_second_test: ASSERTION FAILED at rust/kernel/lib.rs:256 [ 1.928723] Expected 42 >= 43 to be true, but is false [ 1.929834] # my_second_test.speed: normal [ 1.929868] not ok 2 my_second_test [ 1.930032] # my_test_suite: pass:0 fail:2 skip:0 total:2 [ 1.930153] # Totals: pass:0 fail:2 skip:0 total Link: https://github.com/rust-lang/rust/pull/140514 [1] Reviewed-by: David Gow <davidgow@google.com> Acked-by: Danilo Krummrich <dakr@kernel.org> Link: https://lore.kernel.org/r/20250502215133.1923676-2-ojeda@kernel.org [ Required `KUNIT=y` like for doctests. Used the `cfg_attr` from the TODO comment and clarified its comment now that the stabilization is in beta and thus quite likely stable in Rust 1.88.0. Simplified the `new_body` code by introducing a new variable. Added `#[allow(clippy::incompatible_msrv)]`. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-05-02 23:51:26 +02:00
rust: add #[export] macro Rust has two different tools for generating function declarations to call across the FFI boundary: * bindgen. Generates Rust declarations from a C header. * cbindgen. Generates C headers from Rust declarations. However, we only use bindgen in the kernel. This means that when C code calls a Rust function by name, its signature must be duplicated in both Rust code and a C header, and the signature needs to be kept in sync manually. Introducing cbindgen as a mandatory dependency to build the kernel would be a rather complex and large change, so we do not consider that at this time. Instead, to eliminate this manual checking, introduce a new macro that verifies at compile time that the two function declarations use the same signature. The idea is to run the C declaration through bindgen, and then have rustc verify that the function pointers have the same type. The signature must still be written twice, but at least you can no longer get it wrong. If the signatures don't match, you will get errors that look like this: error[E0308]: `if` and `else` have incompatible types --> <linux>/rust/kernel/print.rs:22:22 | 21 | #[export] | --------- expected because of this 22 | unsafe extern "C" fn rust_fmt_argument( | ^^^^^^^^^^^^^^^^^ expected `u8`, found `i8` | = note: expected fn item `unsafe extern "C" fn(*mut u8, *mut u8, *mut c_void) -> *mut u8 {bindings::rust_fmt_argument}` found fn item `unsafe extern "C" fn(*mut i8, *mut i8, *const c_void) -> *mut i8 {print::rust_fmt_argument}` It is unfortunate that the error message starts out by saying "`if` and `else` have incompatible types", but I believe the rest of the error message is reasonably clear and not too confusing. Reviewed-by: Tamir Duberstein <tamird@gmail.com> Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Alice Ryhl <aliceryhl@google.com> Link: https://lore.kernel.org/r/20250303-export-macro-v3-3-41fbad85a27f@google.com Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-03-03 08:45:14 +00:00
rust: types: add `ForLt` trait for higher-ranked lifetime support There are a few cases, e.g. when dealing with data referencing each other, one might want to write code that is generic over lifetimes. For example, if you want to take a function that takes `&'a Foo` and gives `Bar<'a>`, you can write: f: impl for<'a> FnOnce(&'a Foo) -> Bar<'a>, However, it becomes tricky when you want that function to not have a fixed `Bar`, but have it be generic again. In this case, one needs something that is generic over types that are themselves generic over lifetimes. `ForLt` provides such support. It provides a trait `ForLt` which describes a type generic over a lifetime. One may use `ForLt::Of<'a>` to get an instance of a type for a specific lifetime. For the case of cross referencing, one would almost always want the lifetime to be covariant. Therefore this is also made a requirement for the `ForLt` trait, so functions with `ForLt` trait bound can assume covariance. A macro `ForLt!()` is provided to be able to obtain a type that implements `ForLt`. For example, `ForLt!(for<'a> Bar<'a>)` would yield a type that `<TheType as ForLt>::Of<'a>` is `Bar<'a>`. This also works with lifetime elision, e.g. `ForLt!(Bar<'_>)` or for types without lifetime at all, e.g. `ForLt!(u32)`. The API design draws inspiration from the higher-kinded-types [1] crate, however a different design decision has been taken (e.g. covariance requirement) and the implementation is independent. License headers use "Apache-2.0 OR MIT" because I anticipate this to be used in pin-init crate too which is licensed as such. Link: https://docs.rs/higher-kinded-types/ [1] Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Eliot Courtney <ecourtney@nvidia.com> Signed-off-by: Gary Guo <gary@garyguo.net> Acked-by: Miguel Ojeda <ojeda@kernel.org> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com> Link: https://patch.msgid.link/20260525202921.124698-23-dakr@kernel.org [ Handle macro_rules! invocations in the ForLt! proc macro's covariance and WF checks. Since proc macros cannot expand macro_rules!, add a visit_macro() implementation to conservatively assume macro invocations may contain lifetimes, forcing them through the compiler-assisted covariance proof. Fix a few typos in the documentation and in the commit message, add empty lines before samples, add missing periods and consistently use markdown. - Danilo ] Signed-off-by: Danilo Krummrich <dakr@kernel.org>
2026-05-25 22:21:09 +02:00
rust: macros: add `paste!` proc macro This macro provides a flexible way to concatenated identifiers together and it allows the resulting identifier to be used to declare new items, which `concat_idents!` does not allow. It also allows identifiers to be transformed before concatenated. The `concat_idents!` example let x_1 = 42; let x_2 = concat_idents!(x, _1); assert!(x_1 == x_2); can be written with `paste!` macro like this: let x_1 = 42; let x_2 = paste!([<x _1>]); assert!(x_1 == x_2); However `paste!` macro is more flexible because it can be used to create a new variable: let x_1 = 42; paste!(let [<x _2>] = [<x _1>];); assert!(x_1 == x_2); While this is not possible with `concat_idents!`. This macro is similar to the `paste!` crate [1], but this is a fresh implementation to avoid vendoring large amount of code directly. Also, I have augmented it to provide a way to specify span of the resulting token, allowing precise control. For example, this code is broken because the variable is declared inside the macro, so Rust macro hygiene rules prevents access from the outside: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of the macro. paste!(let [<$id>] = 1;) } } m!(a); let _ = a; In this version of `paste!` macro I added a `span` modifier to allow this: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of `$id`. paste!(let [<$id:span>] = 1;) } } m!(a); let _ = a; Link: http://docs.rs/paste/ [1] Signed-off-by: Gary Guo <gary@garyguo.net> Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Reviewed-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Link: https://lore.kernel.org/r/20230628171108.1150742-1-gary@garyguo.net [ Added SPDX license identifier as discussed in the list and fixed typo. ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2023-06-28 18:11:01 +01:00
rust: macros: ignore example with module parameters `ModuleParamAccess` uses `SetOnce`, which depends on the helper functions so the `macros` crate example under `rusttest` fails to build: ---- rust/macros/lib.rs - module (line 62) stdout ---- error: linking with `cc` failed: exit status: 1 | = note: "cc" "-m64" ... = note: some arguments are omitted. use `--verbose` to show all linker arguments = note: rust-lld: error: undefined symbol: rust_helper_atomic_try_cmpxchg_relaxed >>> referenced by kernel.ecd446ce39a5fcbb-cgu.3 >>> kernel.kernel.ecd446ce39a5fcbb-cgu.3.rcgu.o:(kernel::sync::set_once::SetOnce$LT$T$GT$::populate::h8b02644e30bd70bc) in archive ./rust/test/libkernel.rlib rust-lld: error: undefined symbol: rust_helper_atomic_set_release >>> referenced by kernel.ecd446ce39a5fcbb-cgu.3 >>> kernel.kernel.ecd446ce39a5fcbb-cgu.3.rcgu.o:(kernel::sync::set_once::SetOnce$LT$T$GT$::populate::h8b02644e30bd70bc) in archive ./rust/test/libkernel.rlib collect2: error: ld returned 1 exit status Thus ignore that example to fix the error. [ Only the first one is needed (the other example does not use parameters), so we can keep it enabled. Thus I removed that second deletion (and reworded a bit). We may want to do something better here later on; on the other hand, we should get KUnit tests for `macros` too eventually, so we may end up removing or repurposing that target anyway, so it is not a big deal. - Miguel ] Reported-by: Miguel Ojeda <ojeda@kernel.org> Closes: https://lore.kernel.org/rust-for-linux/CANiq72mEYacdZmHKvpbahJzO_X_qqYyiSiSTYaWEQZAfp6sbxg@mail.gmail.com/ Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com> Fixes: 0b24f9740f26 ("rust: module: update the module macro with module parameter support") Link: https://patch.msgid.link/20251210.082603.290476643413141778.fujita.tomonori@gmail.com Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2026-01-14 18:16:38 +00:00
rust: add #[export] macro Rust has two different tools for generating function declarations to call across the FFI boundary: * bindgen. Generates Rust declarations from a C header. * cbindgen. Generates C headers from Rust declarations. However, we only use bindgen in the kernel. This means that when C code calls a Rust function by name, its signature must be duplicated in both Rust code and a C header, and the signature needs to be kept in sync manually. Introducing cbindgen as a mandatory dependency to build the kernel would be a rather complex and large change, so we do not consider that at this time. Instead, to eliminate this manual checking, introduce a new macro that verifies at compile time that the two function declarations use the same signature. The idea is to run the C declaration through bindgen, and then have rustc verify that the function pointers have the same type. The signature must still be written twice, but at least you can no longer get it wrong. If the signatures don't match, you will get errors that look like this: error[E0308]: `if` and `else` have incompatible types --> <linux>/rust/kernel/print.rs:22:22 | 21 | #[export] | --------- expected because of this 22 | unsafe extern "C" fn rust_fmt_argument( | ^^^^^^^^^^^^^^^^^ expected `u8`, found `i8` | = note: expected fn item `unsafe extern "C" fn(*mut u8, *mut u8, *mut c_void) -> *mut u8 {bindings::rust_fmt_argument}` found fn item `unsafe extern "C" fn(*mut i8, *mut i8, *const c_void) -> *mut i8 {print::rust_fmt_argument}` It is unfortunate that the error message starts out by saying "`if` and `else` have incompatible types", but I believe the rest of the error message is reasonably clear and not too confusing. Reviewed-by: Tamir Duberstein <tamird@gmail.com> Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Alice Ryhl <aliceryhl@google.com> Link: https://lore.kernel.org/r/20250303-export-macro-v3-3-41fbad85a27f@google.com Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-03-03 08:45:14 +00:00
rust: add #[export] macro Rust has two different tools for generating function declarations to call across the FFI boundary: * bindgen. Generates Rust declarations from a C header. * cbindgen. Generates C headers from Rust declarations. However, we only use bindgen in the kernel. This means that when C code calls a Rust function by name, its signature must be duplicated in both Rust code and a C header, and the signature needs to be kept in sync manually. Introducing cbindgen as a mandatory dependency to build the kernel would be a rather complex and large change, so we do not consider that at this time. Instead, to eliminate this manual checking, introduce a new macro that verifies at compile time that the two function declarations use the same signature. The idea is to run the C declaration through bindgen, and then have rustc verify that the function pointers have the same type. The signature must still be written twice, but at least you can no longer get it wrong. If the signatures don't match, you will get errors that look like this: error[E0308]: `if` and `else` have incompatible types --> <linux>/rust/kernel/print.rs:22:22 | 21 | #[export] | --------- expected because of this 22 | unsafe extern "C" fn rust_fmt_argument( | ^^^^^^^^^^^^^^^^^ expected `u8`, found `i8` | = note: expected fn item `unsafe extern "C" fn(*mut u8, *mut u8, *mut c_void) -> *mut u8 {bindings::rust_fmt_argument}` found fn item `unsafe extern "C" fn(*mut i8, *mut i8, *const c_void) -> *mut i8 {print::rust_fmt_argument}` It is unfortunate that the error message starts out by saying "`if` and `else` have incompatible types", but I believe the rest of the error message is reasonably clear and not too confusing. Reviewed-by: Tamir Duberstein <tamird@gmail.com> Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Alice Ryhl <aliceryhl@google.com> Link: https://lore.kernel.org/r/20250303-export-macro-v3-3-41fbad85a27f@google.com Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-03-03 08:45:14 +00:00
rust: macros: add `paste!` proc macro This macro provides a flexible way to concatenated identifiers together and it allows the resulting identifier to be used to declare new items, which `concat_idents!` does not allow. It also allows identifiers to be transformed before concatenated. The `concat_idents!` example let x_1 = 42; let x_2 = concat_idents!(x, _1); assert!(x_1 == x_2); can be written with `paste!` macro like this: let x_1 = 42; let x_2 = paste!([<x _1>]); assert!(x_1 == x_2); However `paste!` macro is more flexible because it can be used to create a new variable: let x_1 = 42; paste!(let [<x _2>] = [<x _1>];); assert!(x_1 == x_2); While this is not possible with `concat_idents!`. This macro is similar to the `paste!` crate [1], but this is a fresh implementation to avoid vendoring large amount of code directly. Also, I have augmented it to provide a way to specify span of the resulting token, allowing precise control. For example, this code is broken because the variable is declared inside the macro, so Rust macro hygiene rules prevents access from the outside: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of the macro. paste!(let [<$id>] = 1;) } } m!(a); let _ = a; In this version of `paste!` macro I added a `span` modifier to allow this: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of `$id`. paste!(let [<$id:span>] = 1;) } } m!(a); let _ = a; Link: http://docs.rs/paste/ [1] Signed-off-by: Gary Guo <gary@garyguo.net> Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Reviewed-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Link: https://lore.kernel.org/r/20230628171108.1150742-1-gary@garyguo.net [ Added SPDX license identifier as discussed in the list and fixed typo. ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2023-06-28 18:11:01 +01:00
rust: macros: add `paste!` proc macro This macro provides a flexible way to concatenated identifiers together and it allows the resulting identifier to be used to declare new items, which `concat_idents!` does not allow. It also allows identifiers to be transformed before concatenated. The `concat_idents!` example let x_1 = 42; let x_2 = concat_idents!(x, _1); assert!(x_1 == x_2); can be written with `paste!` macro like this: let x_1 = 42; let x_2 = paste!([<x _1>]); assert!(x_1 == x_2); However `paste!` macro is more flexible because it can be used to create a new variable: let x_1 = 42; paste!(let [<x _2>] = [<x _1>];); assert!(x_1 == x_2); While this is not possible with `concat_idents!`. This macro is similar to the `paste!` crate [1], but this is a fresh implementation to avoid vendoring large amount of code directly. Also, I have augmented it to provide a way to specify span of the resulting token, allowing precise control. For example, this code is broken because the variable is declared inside the macro, so Rust macro hygiene rules prevents access from the outside: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of the macro. paste!(let [<$id>] = 1;) } } m!(a); let _ = a; In this version of `paste!` macro I added a `span` modifier to allow this: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of `$id`. paste!(let [<$id:span>] = 1;) } } m!(a); let _ = a; Link: http://docs.rs/paste/ [1] Signed-off-by: Gary Guo <gary@garyguo.net> Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Reviewed-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Link: https://lore.kernel.org/r/20230628171108.1150742-1-gary@garyguo.net [ Added SPDX license identifier as discussed in the list and fixed typo. ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2023-06-28 18:11:01 +01:00
rust: macros: add `paste!` proc macro This macro provides a flexible way to concatenated identifiers together and it allows the resulting identifier to be used to declare new items, which `concat_idents!` does not allow. It also allows identifiers to be transformed before concatenated. The `concat_idents!` example let x_1 = 42; let x_2 = concat_idents!(x, _1); assert!(x_1 == x_2); can be written with `paste!` macro like this: let x_1 = 42; let x_2 = paste!([<x _1>]); assert!(x_1 == x_2); However `paste!` macro is more flexible because it can be used to create a new variable: let x_1 = 42; paste!(let [<x _2>] = [<x _1>];); assert!(x_1 == x_2); While this is not possible with `concat_idents!`. This macro is similar to the `paste!` crate [1], but this is a fresh implementation to avoid vendoring large amount of code directly. Also, I have augmented it to provide a way to specify span of the resulting token, allowing precise control. For example, this code is broken because the variable is declared inside the macro, so Rust macro hygiene rules prevents access from the outside: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of the macro. paste!(let [<$id>] = 1;) } } m!(a); let _ = a; In this version of `paste!` macro I added a `span` modifier to allow this: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of `$id`. paste!(let [<$id:span>] = 1;) } } m!(a); let _ = a; Link: http://docs.rs/paste/ [1] Signed-off-by: Gary Guo <gary@garyguo.net> Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Reviewed-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Link: https://lore.kernel.org/r/20230628171108.1150742-1-gary@garyguo.net [ Added SPDX license identifier as discussed in the list and fixed typo. ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2023-06-28 18:11:01 +01:00
rust: macros: add `paste!` proc macro This macro provides a flexible way to concatenated identifiers together and it allows the resulting identifier to be used to declare new items, which `concat_idents!` does not allow. It also allows identifiers to be transformed before concatenated. The `concat_idents!` example let x_1 = 42; let x_2 = concat_idents!(x, _1); assert!(x_1 == x_2); can be written with `paste!` macro like this: let x_1 = 42; let x_2 = paste!([<x _1>]); assert!(x_1 == x_2); However `paste!` macro is more flexible because it can be used to create a new variable: let x_1 = 42; paste!(let [<x _2>] = [<x _1>];); assert!(x_1 == x_2); While this is not possible with `concat_idents!`. This macro is similar to the `paste!` crate [1], but this is a fresh implementation to avoid vendoring large amount of code directly. Also, I have augmented it to provide a way to specify span of the resulting token, allowing precise control. For example, this code is broken because the variable is declared inside the macro, so Rust macro hygiene rules prevents access from the outside: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of the macro. paste!(let [<$id>] = 1;) } } m!(a); let _ = a; In this version of `paste!` macro I added a `span` modifier to allow this: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of `$id`. paste!(let [<$id:span>] = 1;) } } m!(a); let _ = a; Link: http://docs.rs/paste/ [1] Signed-off-by: Gary Guo <gary@garyguo.net> Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Reviewed-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Link: https://lore.kernel.org/r/20230628171108.1150742-1-gary@garyguo.net [ Added SPDX license identifier as discussed in the list and fixed typo. ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2023-06-28 18:11:01 +01:00
rust: macros: add `paste!` proc macro This macro provides a flexible way to concatenated identifiers together and it allows the resulting identifier to be used to declare new items, which `concat_idents!` does not allow. It also allows identifiers to be transformed before concatenated. The `concat_idents!` example let x_1 = 42; let x_2 = concat_idents!(x, _1); assert!(x_1 == x_2); can be written with `paste!` macro like this: let x_1 = 42; let x_2 = paste!([<x _1>]); assert!(x_1 == x_2); However `paste!` macro is more flexible because it can be used to create a new variable: let x_1 = 42; paste!(let [<x _2>] = [<x _1>];); assert!(x_1 == x_2); While this is not possible with `concat_idents!`. This macro is similar to the `paste!` crate [1], but this is a fresh implementation to avoid vendoring large amount of code directly. Also, I have augmented it to provide a way to specify span of the resulting token, allowing precise control. For example, this code is broken because the variable is declared inside the macro, so Rust macro hygiene rules prevents access from the outside: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of the macro. paste!(let [<$id>] = 1;) } } m!(a); let _ = a; In this version of `paste!` macro I added a `span` modifier to allow this: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of `$id`. paste!(let [<$id:span>] = 1;) } } m!(a); let _ = a; Link: http://docs.rs/paste/ [1] Signed-off-by: Gary Guo <gary@garyguo.net> Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Reviewed-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Link: https://lore.kernel.org/r/20230628171108.1150742-1-gary@garyguo.net [ Added SPDX license identifier as discussed in the list and fixed typo. ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2023-06-28 18:11:01 +01:00
rust: macros: add `paste!` proc macro This macro provides a flexible way to concatenated identifiers together and it allows the resulting identifier to be used to declare new items, which `concat_idents!` does not allow. It also allows identifiers to be transformed before concatenated. The `concat_idents!` example let x_1 = 42; let x_2 = concat_idents!(x, _1); assert!(x_1 == x_2); can be written with `paste!` macro like this: let x_1 = 42; let x_2 = paste!([<x _1>]); assert!(x_1 == x_2); However `paste!` macro is more flexible because it can be used to create a new variable: let x_1 = 42; paste!(let [<x _2>] = [<x _1>];); assert!(x_1 == x_2); While this is not possible with `concat_idents!`. This macro is similar to the `paste!` crate [1], but this is a fresh implementation to avoid vendoring large amount of code directly. Also, I have augmented it to provide a way to specify span of the resulting token, allowing precise control. For example, this code is broken because the variable is declared inside the macro, so Rust macro hygiene rules prevents access from the outside: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of the macro. paste!(let [<$id>] = 1;) } } m!(a); let _ = a; In this version of `paste!` macro I added a `span` modifier to allow this: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of `$id`. paste!(let [<$id:span>] = 1;) } } m!(a); let _ = a; Link: http://docs.rs/paste/ [1] Signed-off-by: Gary Guo <gary@garyguo.net> Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Reviewed-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Link: https://lore.kernel.org/r/20230628171108.1150742-1-gary@garyguo.net [ Added SPDX license identifier as discussed in the list and fixed typo. ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2023-06-28 18:11:01 +01:00
rust: macros: add `paste!` proc macro This macro provides a flexible way to concatenated identifiers together and it allows the resulting identifier to be used to declare new items, which `concat_idents!` does not allow. It also allows identifiers to be transformed before concatenated. The `concat_idents!` example let x_1 = 42; let x_2 = concat_idents!(x, _1); assert!(x_1 == x_2); can be written with `paste!` macro like this: let x_1 = 42; let x_2 = paste!([<x _1>]); assert!(x_1 == x_2); However `paste!` macro is more flexible because it can be used to create a new variable: let x_1 = 42; paste!(let [<x _2>] = [<x _1>];); assert!(x_1 == x_2); While this is not possible with `concat_idents!`. This macro is similar to the `paste!` crate [1], but this is a fresh implementation to avoid vendoring large amount of code directly. Also, I have augmented it to provide a way to specify span of the resulting token, allowing precise control. For example, this code is broken because the variable is declared inside the macro, so Rust macro hygiene rules prevents access from the outside: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of the macro. paste!(let [<$id>] = 1;) } } m!(a); let _ = a; In this version of `paste!` macro I added a `span` modifier to allow this: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of `$id`. paste!(let [<$id:span>] = 1;) } } m!(a); let _ = a; Link: http://docs.rs/paste/ [1] Signed-off-by: Gary Guo <gary@garyguo.net> Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Reviewed-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Link: https://lore.kernel.org/r/20230628171108.1150742-1-gary@garyguo.net [ Added SPDX license identifier as discussed in the list and fixed typo. ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2023-06-28 18:11:01 +01:00
rust: macros: add `paste!` proc macro This macro provides a flexible way to concatenated identifiers together and it allows the resulting identifier to be used to declare new items, which `concat_idents!` does not allow. It also allows identifiers to be transformed before concatenated. The `concat_idents!` example let x_1 = 42; let x_2 = concat_idents!(x, _1); assert!(x_1 == x_2); can be written with `paste!` macro like this: let x_1 = 42; let x_2 = paste!([<x _1>]); assert!(x_1 == x_2); However `paste!` macro is more flexible because it can be used to create a new variable: let x_1 = 42; paste!(let [<x _2>] = [<x _1>];); assert!(x_1 == x_2); While this is not possible with `concat_idents!`. This macro is similar to the `paste!` crate [1], but this is a fresh implementation to avoid vendoring large amount of code directly. Also, I have augmented it to provide a way to specify span of the resulting token, allowing precise control. For example, this code is broken because the variable is declared inside the macro, so Rust macro hygiene rules prevents access from the outside: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of the macro. paste!(let [<$id>] = 1;) } } m!(a); let _ = a; In this version of `paste!` macro I added a `span` modifier to allow this: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of `$id`. paste!(let [<$id:span>] = 1;) } } m!(a); let _ = a; Link: http://docs.rs/paste/ [1] Signed-off-by: Gary Guo <gary@garyguo.net> Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Reviewed-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Link: https://lore.kernel.org/r/20230628171108.1150742-1-gary@garyguo.net [ Added SPDX license identifier as discussed in the list and fixed typo. ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2023-06-28 18:11:01 +01:00
rust: macros: add `paste!` proc macro This macro provides a flexible way to concatenated identifiers together and it allows the resulting identifier to be used to declare new items, which `concat_idents!` does not allow. It also allows identifiers to be transformed before concatenated. The `concat_idents!` example let x_1 = 42; let x_2 = concat_idents!(x, _1); assert!(x_1 == x_2); can be written with `paste!` macro like this: let x_1 = 42; let x_2 = paste!([<x _1>]); assert!(x_1 == x_2); However `paste!` macro is more flexible because it can be used to create a new variable: let x_1 = 42; paste!(let [<x _2>] = [<x _1>];); assert!(x_1 == x_2); While this is not possible with `concat_idents!`. This macro is similar to the `paste!` crate [1], but this is a fresh implementation to avoid vendoring large amount of code directly. Also, I have augmented it to provide a way to specify span of the resulting token, allowing precise control. For example, this code is broken because the variable is declared inside the macro, so Rust macro hygiene rules prevents access from the outside: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of the macro. paste!(let [<$id>] = 1;) } } m!(a); let _ = a; In this version of `paste!` macro I added a `span` modifier to allow this: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of `$id`. paste!(let [<$id:span>] = 1;) } } m!(a); let _ = a; Link: http://docs.rs/paste/ [1] Signed-off-by: Gary Guo <gary@garyguo.net> Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Reviewed-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Link: https://lore.kernel.org/r/20230628171108.1150742-1-gary@garyguo.net [ Added SPDX license identifier as discussed in the list and fixed typo. ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2023-06-28 18:11:01 +01:00
rust: macros: add `paste!` proc macro This macro provides a flexible way to concatenated identifiers together and it allows the resulting identifier to be used to declare new items, which `concat_idents!` does not allow. It also allows identifiers to be transformed before concatenated. The `concat_idents!` example let x_1 = 42; let x_2 = concat_idents!(x, _1); assert!(x_1 == x_2); can be written with `paste!` macro like this: let x_1 = 42; let x_2 = paste!([<x _1>]); assert!(x_1 == x_2); However `paste!` macro is more flexible because it can be used to create a new variable: let x_1 = 42; paste!(let [<x _2>] = [<x _1>];); assert!(x_1 == x_2); While this is not possible with `concat_idents!`. This macro is similar to the `paste!` crate [1], but this is a fresh implementation to avoid vendoring large amount of code directly. Also, I have augmented it to provide a way to specify span of the resulting token, allowing precise control. For example, this code is broken because the variable is declared inside the macro, so Rust macro hygiene rules prevents access from the outside: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of the macro. paste!(let [<$id>] = 1;) } } m!(a); let _ = a; In this version of `paste!` macro I added a `span` modifier to allow this: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of `$id`. paste!(let [<$id:span>] = 1;) } } m!(a); let _ = a; Link: http://docs.rs/paste/ [1] Signed-off-by: Gary Guo <gary@garyguo.net> Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Reviewed-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Link: https://lore.kernel.org/r/20230628171108.1150742-1-gary@garyguo.net [ Added SPDX license identifier as discussed in the list and fixed typo. ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2023-06-28 18:11:01 +01:00
rust: macros: add `paste!` proc macro This macro provides a flexible way to concatenated identifiers together and it allows the resulting identifier to be used to declare new items, which `concat_idents!` does not allow. It also allows identifiers to be transformed before concatenated. The `concat_idents!` example let x_1 = 42; let x_2 = concat_idents!(x, _1); assert!(x_1 == x_2); can be written with `paste!` macro like this: let x_1 = 42; let x_2 = paste!([<x _1>]); assert!(x_1 == x_2); However `paste!` macro is more flexible because it can be used to create a new variable: let x_1 = 42; paste!(let [<x _2>] = [<x _1>];); assert!(x_1 == x_2); While this is not possible with `concat_idents!`. This macro is similar to the `paste!` crate [1], but this is a fresh implementation to avoid vendoring large amount of code directly. Also, I have augmented it to provide a way to specify span of the resulting token, allowing precise control. For example, this code is broken because the variable is declared inside the macro, so Rust macro hygiene rules prevents access from the outside: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of the macro. paste!(let [<$id>] = 1;) } } m!(a); let _ = a; In this version of `paste!` macro I added a `span` modifier to allow this: macro_rules! m { ($id: ident) => { // The resulting token has hygiene of `$id`. paste!(let [<$id:span>] = 1;) } } m!(a); let _ = a; Link: http://docs.rs/paste/ [1] Signed-off-by: Gary Guo <gary@garyguo.net> Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Reviewed-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Link: https://lore.kernel.org/r/20230628171108.1150742-1-gary@garyguo.net [ Added SPDX license identifier as discussed in the list and fixed typo. ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2023-06-28 18:11:01 +01:00
rust: types: add `ForLt` trait for higher-ranked lifetime support There are a few cases, e.g. when dealing with data referencing each other, one might want to write code that is generic over lifetimes. For example, if you want to take a function that takes `&'a Foo` and gives `Bar<'a>`, you can write: f: impl for<'a> FnOnce(&'a Foo) -> Bar<'a>, However, it becomes tricky when you want that function to not have a fixed `Bar`, but have it be generic again. In this case, one needs something that is generic over types that are themselves generic over lifetimes. `ForLt` provides such support. It provides a trait `ForLt` which describes a type generic over a lifetime. One may use `ForLt::Of<'a>` to get an instance of a type for a specific lifetime. For the case of cross referencing, one would almost always want the lifetime to be covariant. Therefore this is also made a requirement for the `ForLt` trait, so functions with `ForLt` trait bound can assume covariance. A macro `ForLt!()` is provided to be able to obtain a type that implements `ForLt`. For example, `ForLt!(for<'a> Bar<'a>)` would yield a type that `<TheType as ForLt>::Of<'a>` is `Bar<'a>`. This also works with lifetime elision, e.g. `ForLt!(Bar<'_>)` or for types without lifetime at all, e.g. `ForLt!(u32)`. The API design draws inspiration from the higher-kinded-types [1] crate, however a different design decision has been taken (e.g. covariance requirement) and the implementation is independent. License headers use "Apache-2.0 OR MIT" because I anticipate this to be used in pin-init crate too which is licensed as such. Link: https://docs.rs/higher-kinded-types/ [1] Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Eliot Courtney <ecourtney@nvidia.com> Signed-off-by: Gary Guo <gary@garyguo.net> Acked-by: Miguel Ojeda <ojeda@kernel.org> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com> Link: https://patch.msgid.link/20260525202921.124698-23-dakr@kernel.org [ Handle macro_rules! invocations in the ForLt! proc macro's covariance and WF checks. Since proc macros cannot expand macro_rules!, add a visit_macro() implementation to conservatively assume macro invocations may contain lifetimes, forcing them through the compiler-assisted covariance proof. Fix a few typos in the documentation and in the commit message, add empty lines before samples, add missing periods and consistently use markdown. - Danilo ] Signed-off-by: Danilo Krummrich <dakr@kernel.org>
2026-05-25 22:21:09 +02:00