Merge branch '⬆️-nightly-2022-05-20' into 🦆

Author: yvt

doc/toolchain_limitations.md

@@ -366,28 +366,6 @@ const _: () = { b"".iter(); };
 ```
 
 
-### `[tag:const_array_assume_init]` `MaybeUninit::array_assume_init` is not `const fn`
-
-```rust
-#![feature(maybe_uninit_array_assume_init)]
-use core::mem::MaybeUninit;
-assert!(matches!(
-    unsafe { MaybeUninit::array_assume_init([MaybeUninit::new(42)]) },
-    [42]
-));
-```
-
-```rust,compile_fail,E0015
-#![feature(maybe_uninit_array_assume_init)]
-use core::mem::MaybeUninit;
-const _: () = assert!(matches!(
-    // error[E0015]: cannot call non-const fn `MaybeUninit::<i32>::
-    // array_assume_init::<1_usize>` in constants
-    unsafe { MaybeUninit::array_assume_init([MaybeUninit::new(42)]) },
-    [42]
-));
-```
-
 ### `[tag:const_uninit_array]` `MaybeUninit::uninit_array` is unstable
 
 ```rust,compile_fail,E0658

rust-toolchain

@@ -1 +1 @@
-nightly-2022-03-30
+nightly-2022-05-20

src/r3_core/src/bind.rs

@@ -1216,7 +1216,8 @@ macro_rules! impl_fn_bind {
             type BoundFn<T, Output, $( $RuntimeBinderI, )*>
             where
                 $( $RuntimeBinderI: RuntimeBinder, )*
-                T: Copy + Send + 'static,
+                T: for<'call> FnOnce($( $RuntimeBinderI::Target<'call>, )*)
+                    -> Output + Copy + Send + 'static,
              = impl FnOnce() -> Output + Copy + Send + 'static;
 
             const fn bind_inner<
@@ -1345,8 +1346,8 @@ where
 
 type MappedBoundFn<InnerBoundFn, Output, Mapper, NewOutput>
 where
-    InnerBoundFn: Copy + Send + 'static,
-    Mapper: Copy + Send + 'static,
+    InnerBoundFn: FnOnce() -> Output + Copy + Send + 'static,
+    Mapper: FnOnce(Output) -> NewOutput + Copy + Send + 'static,
 = impl FnOnce() -> NewOutput + Copy + Send + 'static;
 
 const fn map_bind_inner<InnerBoundFn, Output, Mapper, NewOutput>(

src/r3_core/src/lib.rs

@@ -1,6 +1,9 @@
+#![feature(const_maybe_uninit_array_assume_init)]
 #![feature(const_fn_floating_point_arithmetic)]
 #![feature(const_nonnull_slice_from_raw_parts)]
+#![feature(const_maybe_uninit_uninit_array)]
 #![feature(const_maybe_uninit_assume_init)]
+#![feature(maybe_uninit_array_assume_init)]
 #![feature(const_maybe_uninit_as_mut_ptr)]
 #![feature(nonnull_slice_from_raw_parts)]
 #![feature(arbitrary_enum_discriminant)]

src/r3_core/src/time/duration.rs

@@ -222,7 +222,7 @@ impl TryFrom<Duration> for core::time::Duration {
 
 impl fmt::Debug for Duration {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        let abs_dur = core::time::Duration::from_micros((self.micros as i64).abs() as u64);
+        let abs_dur = core::time::Duration::from_micros(self.micros.unsigned_abs().into());
         if self.micros < 0 {
             write!(f, "-")?;
         }

src/r3_core/src/utils/for_times.rs

@@ -232,21 +232,8 @@ macro_rules! const_array_from_fn {
             ))
         }
 
-        // `MaybeUninit::array_assume_init` is not `const fn` yet
-        // [ref:const_array_assume_init]
-        const unsafe fn __assume_init<
-            $($iter_gparam $($iter_gparam_bounds)*,)*
-            const LEN: usize
-        >(array: [MaybeUninit<$ty>; LEN]) -> [$ty; LEN] {
-            // Safety: This is equivalent to `transmute_copy(&array)`. The
-            // memory layout of `[MaybeUninit<T>; $len]` is identical to `[T; $len]`.
-            // We initialized all elements in `array[0..$len]`, so it's safe to
-            // reinterpret that range as `[T; $len]`.
-            unsafe { *(array.as_ptr() as *const _ as *const [$ty; LEN]) }
-        }
-
-        // Safety: See the body of `__assume_init`.
-        unsafe { __assume_init::<$($ctx_t,)* {$len_value}>(array) }
+        // Safety: All elements of `array` are initialized
+        unsafe { MaybeUninit::array_assume_init(array) }
     }};
 }
 

src/r3_core/src/utils/init.rs

@@ -44,12 +44,8 @@ impl<T: Init, const LEN: usize> Init for [T; LEN] {
             i += 1;
         }
 
-        // `MaybeUninit::array_assume_init` is not `const fn` yet
-        // [ref:const_array_assume_init]
-        // Safety: The memory layout of `[MaybeUninit<T>; LEN]` is
-        // identical to `[T; LEN]`. We initialized all elements, so it's
-        // safe to reinterpret that range as `[T; LEN]`.
-        unsafe { super::mem::transmute(array) }
+        // Safety: `array`'s elements are fully initialized
+        unsafe { mem::MaybeUninit::array_assume_init(array) }
     };
 }
 

src/r3_core/src/utils/mem.rs

@@ -44,9 +44,7 @@ mod tests {
                 MaybeUninit::new(2),
                 MaybeUninit::new(3),
             ];
-            // `MaybeUninit::array_assume_init` is not `const fn`
-            // [ref:const_array_assume_init]
-            unsafe { transmute(array) }
+            unsafe { MaybeUninit::array_assume_init(array) }
         };
         assert_eq!(ARRAY1, [1, 2, 3]);
     }

src/r3_kernel/src/lib.rs

@@ -1,4 +1,7 @@
+#![feature(const_maybe_uninit_array_assume_init)]
+#![feature(const_maybe_uninit_uninit_array)]
 #![feature(const_maybe_uninit_assume_init)]
+#![feature(maybe_uninit_array_assume_init)]
 #![feature(const_slice_from_raw_parts)]
 #![feature(maybe_uninit_uninit_array)]
 #![feature(const_precise_live_drops)]

src/r3_port_riscv/CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Changed
 
 - **Breaking (semver-exempt):** Change the target compiler version to `nightly-2022-03-30`
+- **Breaking:** `use_rt!` is now gated behind `riscv-rt` Cargo feature.
 
 ### Fixed