They were stabilized in Rust 1.79.0. Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> --- docs/devel/rust.rst | 9 +++------ rust/qemu-api/src/callbacks.rs | 27 +-------------------------- rust/qemu-api/src/chardev.rs | 2 +- rust/qemu-api/src/qdev.rs | 2 +- rust/qemu-api/src/timer.rs | 2 +- rust/qemu-api/src/vmstate.rs | 2 +- 6 files changed, 8 insertions(+), 36 deletions(-)
diff --git a/docs/devel/rust.rst b/docs/devel/rust.rst index e0ee4a9837d..98e3a33a3ce 100644 --- a/docs/devel/rust.rst +++ b/docs/devel/rust.rst @@ -79,9 +79,6 @@ QEMU supports rustc version 1.83.0 and newer. The following features from relatively new versions of Rust are not used for historical reasons; patches are welcome: -* inline const expression (stable in 1.79.0), currently worked around with - associated constants in the ``FnCall`` trait. - * associated constants are still explicitly marked ``'static`` (`changed in 1.81.0`__) @@ -97,9 +94,9 @@ patches are welcome: before QEMU can use them. For now, there is special code in ``util/error.c`` to support non-NUL-terminated file names. -* associated const equality would be nice to have for some users of - ``callbacks::FnCall``, but is still experimental. ``ASSERT_IS_SOME`` - replaces it. +Associated const equality would be nice to have for some users of +``callbacks::FnCall``, but is still experimental. Const assertions +are used instead. __ https://github.com/rust-lang/rust/pull/125258 diff --git a/rust/qemu-api/src/callbacks.rs b/rust/qemu-api/src/callbacks.rs index 9642a16eb89..dbe2305f509 100644 --- a/rust/qemu-api/src/callbacks.rs +++ b/rust/qemu-api/src/callbacks.rs @@ -113,31 +113,6 @@ /// This is always true for zero-capture closures and function pointers, as long /// as the code is able to name the function in the first place. pub unsafe trait FnCall<Args, R = ()>: 'static + Sync + Sized { - /// Referring to this internal constant asserts that the `Self` type is - /// zero-sized. Can be replaced by an inline const expression in - /// Rust 1.79.0+. - const ASSERT_ZERO_SIZED: () = { assert!(mem::size_of::<Self>() == 0) }; - - /// Referring to this constant asserts that the `Self` type is an actual - /// function type, which can be used to catch incorrect use of `()` - /// at compile time. - /// - /// # Examples - /// - /// ```compile_fail - /// # use qemu_api::callbacks::FnCall; - /// fn call_it<F: for<'a> FnCall<(&'a str,), String>>(_f: &F, s: &str) -> String { - /// let _: () = F::ASSERT_IS_SOME; - /// F::call((s,)) - /// } - /// - /// let s: String = call_it((), "hello world"); // does not compile - /// ``` - /// - /// Note that this can be more simply `const { assert!(F::IS_SOME) }` in - /// Rust 1.79.0 or newer. - const ASSERT_IS_SOME: () = { assert!(Self::IS_SOME) }; - /// `true` if `Self` is an actual function type and not `()`. /// /// # Examples @@ -195,7 +170,7 @@ unsafe impl<F, $($args,)* R> FnCall<($($args,)*), R> for F #[inline(always)] fn call(a: ($($args,)*)) -> R { - let _: () = Self::ASSERT_ZERO_SIZED; + const { assert!(mem::size_of::<Self>() == 0) }; // SAFETY: the safety of this method is the condition for implementing // `FnCall`. As to the `NonNull` idiom to create a zero-sized type, diff --git a/rust/qemu-api/src/chardev.rs b/rust/qemu-api/src/chardev.rs index 6e0590d758e..cb27be52569 100644 --- a/rust/qemu-api/src/chardev.rs +++ b/rust/qemu-api/src/chardev.rs @@ -138,7 +138,7 @@ pub fn enable_handlers< F::call((owner, event)) } - let _: () = CanReceiveFn::ASSERT_IS_SOME; + const { assert!(CanReceiveFn::IS_SOME) }; let receive_cb: Option<unsafe extern "C" fn(*mut c_void, *const u8, c_int)> = if ReceiveFn::is_some() { Some(rust_receive_cb::<T, ReceiveFn>) diff --git a/rust/qemu-api/src/qdev.rs b/rust/qemu-api/src/qdev.rs index 36f02fb57db..52d54a4494e 100644 --- a/rust/qemu-api/src/qdev.rs +++ b/rust/qemu-api/src/qdev.rs @@ -373,7 +373,7 @@ fn do_init_gpio_in( } } - let _: () = F::ASSERT_IS_SOME; + const { assert!(F::IS_SOME) }; unsafe extern "C" fn rust_irq_handler<T, F: for<'a> FnCall<(&'a T, u32, u32)>>( opaque: *mut c_void, line: c_int, diff --git a/rust/qemu-api/src/timer.rs b/rust/qemu-api/src/timer.rs index 0daec62f926..1e639eaf221 100644 --- a/rust/qemu-api/src/timer.rs +++ b/rust/qemu-api/src/timer.rs @@ -56,7 +56,7 @@ pub fn init_full<'timer, 'opaque: 'timer, T, F>( ) where F: for<'a> FnCall<(&'a T,)>, { - let _: () = F::ASSERT_IS_SOME; + const { assert!(F::IS_SOME) }; /// timer expiration callback unsafe extern "C" fn rust_timer_handler<T, F: for<'a> FnCall<(&'a T,)>>( diff --git a/rust/qemu-api/src/vmstate.rs b/rust/qemu-api/src/vmstate.rs index 812f390d780..8515e382135 100644 --- a/rust/qemu-api/src/vmstate.rs +++ b/rust/qemu-api/src/vmstate.rs @@ -457,7 +457,7 @@ macro_rules! vmstate_exist_fn { const fn test_cb_builder__<T, F: for<'a> $crate::callbacks::FnCall<(&'a T, u8), bool>>( _phantom: ::core::marker::PhantomData<F>, ) -> $crate::vmstate::VMSFieldExistCb { - let _: () = F::ASSERT_IS_SOME; + const { assert!(F::IS_SOME) }; $crate::vmstate::rust_vms_test_field_exists::<T, F> } -- 2.51.0
