From aecca0676ddd9e032de4eeda371b81598d3257bb Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 8 Sep 2025 12:49:37 +0200 Subject: rust: use inline const expressions They were stabilized in Rust 1.79.0. Reviewed-by: Zhao Liu Link: https://lore.kernel.org/r/20250908105005.2119297-6-pbonzini@redhat.com Signed-off-by: Paolo Bonzini --- 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 +- 5 files changed, 5 insertions(+), 30 deletions(-) (limited to 'rust/qemu-api/src') diff --git a/rust/qemu-api/src/callbacks.rs b/rust/qemu-api/src/callbacks.rs index 9642a16eb8..dbe2305f50 100644 --- a/rust/qemu-api/src/callbacks.rs +++ b/rust/qemu-api/src/callbacks.rs @@ -113,31 +113,6 @@ use std::{mem, ptr::NonNull}; /// 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: '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::() == 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 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 @@ macro_rules! impl_call { #[inline(always)] fn call(a: ($($args,)*)) -> R { - let _: () = Self::ASSERT_ZERO_SIZED; + const { assert!(mem::size_of::() == 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 6e0590d758..cb27be5256 100644 --- a/rust/qemu-api/src/chardev.rs +++ b/rust/qemu-api/src/chardev.rs @@ -138,7 +138,7 @@ impl CharBackend { F::call((owner, event)) } - let _: () = CanReceiveFn::ASSERT_IS_SOME; + const { assert!(CanReceiveFn::IS_SOME) }; let receive_cb: Option = if ReceiveFn::is_some() { Some(rust_receive_cb::) diff --git a/rust/qemu-api/src/qdev.rs b/rust/qemu-api/src/qdev.rs index 36f02fb57d..52d54a4494 100644 --- a/rust/qemu-api/src/qdev.rs +++ b/rust/qemu-api/src/qdev.rs @@ -373,7 +373,7 @@ where } } - let _: () = F::ASSERT_IS_SOME; + const { assert!(F::IS_SOME) }; unsafe extern "C" fn rust_irq_handler 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 0daec62f92..1e639eaf22 100644 --- a/rust/qemu-api/src/timer.rs +++ b/rust/qemu-api/src/timer.rs @@ -56,7 +56,7 @@ impl Timer { ) 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 FnCall<(&'a T,)>>( diff --git a/rust/qemu-api/src/vmstate.rs b/rust/qemu-api/src/vmstate.rs index 812f390d78..8515e38213 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__ $crate::callbacks::FnCall<(&'a T, u8), bool>>( _phantom: ::core::marker::PhantomData, ) -> $crate::vmstate::VMSFieldExistCb { - let _: () = F::ASSERT_IS_SOME; + const { assert!(F::IS_SOME) }; $crate::vmstate::rust_vms_test_field_exists:: } -- cgit 1.4.1