Auto merge of rust-lang#118433 - matthiaskrgr:rollup-fi9lrwg, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - rust-lang#116839 (Implement thread parking for xous)
 - rust-lang#118265 (remove the memcpy-on-equal-ptrs assumption)
 - rust-lang#118269 (Unify `TraitRefs` and `PolyTraitRefs` in `ValuePairs`)
 - rust-lang#118394 (Remove HIR opkinds)
 - rust-lang#118398 (Add proper cfgs in std)
 - rust-lang#118419 (Eagerly return `ExprKind::Err` on `yield`/`await` in wrong coroutine context)
 - rust-lang#118422 (Fix coroutine validation for mixed panic strategy)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

alloc/src/alloc.rs

@@ -423,12 +423,14 @@ pub mod __alloc_error_handler {
     }
 }
 
+#[cfg(not(no_global_oom_handling))]
 /// Specialize clones into pre-allocated, uninitialized memory.
 /// Used by `Box::clone` and `Rc`/`Arc::make_mut`.
 pub(crate) trait WriteCloneIntoRaw: Sized {
     unsafe fn write_clone_into_raw(&self, target: *mut Self);
 }
 
+#[cfg(not(no_global_oom_handling))]
 impl<T: Clone> WriteCloneIntoRaw for T {
     #[inline]
     default unsafe fn write_clone_into_raw(&self, target: *mut Self) {
@@ -438,6 +440,7 @@ impl<T: Clone> WriteCloneIntoRaw for T {
     }
 }
 
+#[cfg(not(no_global_oom_handling))]
 impl<T: Copy> WriteCloneIntoRaw for T {
     #[inline]
     unsafe fn write_clone_into_raw(&self, target: *mut Self) {

alloc/src/collections/mod.rs

@@ -148,6 +148,7 @@ impl Display for TryReserveError {
 
 /// An intermediate trait for specialization of `Extend`.
 #[doc(hidden)]
+#[cfg(not(no_global_oom_handling))]
 trait SpecExtend<I: IntoIterator> {
     /// Extends `self` with the contents of the given iterator.
     fn spec_extend(&mut self, iter: I);

alloc/src/rc.rs

@@ -2023,6 +2023,7 @@ impl<T, A: Allocator> Rc<[T], A> {
     }
 }
 
+#[cfg(not(no_global_oom_handling))]
 /// Specialization trait used for `From<&[T]>`.
 trait RcFromSlice<T> {
     fn from_slice(slice: &[T]) -> Self;

alloc/src/sync.rs

@@ -3503,6 +3503,7 @@ impl<T> FromIterator<T> for Arc<[T]> {
     }
 }
 
+#[cfg(not(no_global_oom_handling))]
 /// Specialization trait used for collecting into `Arc<[T]>`.
 trait ToArcSlice<T>: Iterator<Item = T> + Sized {
     fn to_arc_slice(self) -> Arc<[T]>;

alloc/src/vec/mod.rs

@@ -58,6 +58,7 @@ use core::cmp;
 use core::cmp::Ordering;
 use core::fmt;
 use core::hash::{Hash, Hasher};
+#[cfg(not(no_global_oom_handling))]
 use core::iter;
 use core::marker::PhantomData;
 use core::mem::{self, ManuallyDrop, MaybeUninit, SizedTypeProperties};
@@ -101,6 +102,7 @@ mod into_iter;
 #[cfg(not(no_global_oom_handling))]
 use self::is_zero::IsZero;
 
+#[cfg(not(no_global_oom_handling))]
 mod is_zero;
 
 #[cfg(not(no_global_oom_handling))]
@@ -2599,6 +2601,7 @@ pub fn from_elem_in<T: Clone, A: Allocator>(elem: T, n: usize, alloc: A) -> Vec<
     <T as SpecFromElem>::from_elem(elem, n, alloc)
 }
 
+#[cfg(not(no_global_oom_handling))]
 trait ExtendFromWithinSpec {
     /// # Safety
     ///
@@ -2607,6 +2610,7 @@ trait ExtendFromWithinSpec {
     unsafe fn spec_extend_from_within(&mut self, src: Range<usize>);
 }
 
+#[cfg(not(no_global_oom_handling))]
 impl<T: Clone, A: Allocator> ExtendFromWithinSpec for Vec<T, A> {
     default unsafe fn spec_extend_from_within(&mut self, src: Range<usize>) {
         // SAFETY:
@@ -2626,6 +2630,7 @@ impl<T: Clone, A: Allocator> ExtendFromWithinSpec for Vec<T, A> {
     }
 }
 
+#[cfg(not(no_global_oom_handling))]
 impl<T: Copy, A: Allocator> ExtendFromWithinSpec for Vec<T, A> {
     unsafe fn spec_extend_from_within(&mut self, src: Range<usize>) {
         let count = src.len();

core/src/lib.rs

@@ -24,9 +24,8 @@
 //!   which are generated by Rust codegen backends. Additionally, this library can make explicit
 //!   calls to `strlen`. Their signatures are the same as found in C, but there are extra
 //!   assumptions about their semantics: For `memcpy`, `memmove`, `memset`, `memcmp`, and `bcmp`, if
-//!   the `n` parameter is 0, the function is assumed to not be UB. Furthermore, for `memcpy`, if
-//!   source and target pointer are equal, the function is assumed to not be UB.
-//!   (Note that these are standard assumptions among compilers:
+//!   the `n` parameter is 0, the function is assumed to not be UB, even if the pointers are NULL or
+//!   dangling. (Note that making extra assumptions about these functions is common among compilers:
 //!   [clang](https://reviews.llvm.org/D86993) and [GCC](https://gcc.gnu.org/onlinedocs/gcc/Standards.html#C-Language) do the same.)
 //!   These functions are often provided by the system libc, but can also be provided by the
 //!   [compiler-builtins crate](https://crates.io/crates/compiler_builtins).

std/src/lib.rs

@@ -336,6 +336,7 @@
 #![feature(portable_simd)]
 #![feature(prelude_2024)]
 #![feature(ptr_as_uninit)]
+#![feature(ptr_from_ref)]
 #![feature(raw_os_nonzero)]
 #![feature(round_ties_even)]
 #![feature(slice_internals)]

std/src/sys/xous/mod.rs

@@ -28,7 +28,6 @@ pub mod process;
 pub mod stdio;
 pub mod thread;
 pub mod thread_local_key;
-#[path = "../unsupported/thread_parking.rs"]
 pub mod thread_parking;
 pub mod time;
 

std/src/sys/xous/thread_parking.rs

@@ -0,0 +1,94 @@
+use crate::os::xous::ffi::{blocking_scalar, scalar};
+use crate::os::xous::services::{ticktimer_server, TicktimerScalar};
+use crate::pin::Pin;
+use crate::ptr;
+use crate::sync::atomic::{
+    AtomicI8,
+    Ordering::{Acquire, Release},
+};
+use crate::time::Duration;
+
+const NOTIFIED: i8 = 1;
+const EMPTY: i8 = 0;
+const PARKED: i8 = -1;
+
+pub struct Parker {
+    state: AtomicI8,
+}
+
+impl Parker {
+    pub unsafe fn new_in_place(parker: *mut Parker) {
+        unsafe { parker.write(Parker { state: AtomicI8::new(EMPTY) }) }
+    }
+
+    fn index(&self) -> usize {
+        ptr::from_ref(self).addr()
+    }
+
+    pub unsafe fn park(self: Pin<&Self>) {
+        // Change NOTIFIED to EMPTY and EMPTY to PARKED.
+        let state = self.state.fetch_sub(1, Acquire);
+        if state == NOTIFIED {
+            return;
+        }
+
+        // The state was set to PARKED. Wait until the `unpark` wakes us up.
+        blocking_scalar(
+            ticktimer_server(),
+            TicktimerScalar::WaitForCondition(self.index(), 0).into(),
+        )
+        .expect("failed to send WaitForCondition command");
+
+        self.state.swap(EMPTY, Acquire);
+    }
+
+    pub unsafe fn park_timeout(self: Pin<&Self>, timeout: Duration) {
+        // Change NOTIFIED to EMPTY and EMPTY to PARKED.
+        let state = self.state.fetch_sub(1, Acquire);
+        if state == NOTIFIED {
+            return;
+        }
+
+        // A value of zero indicates an indefinite wait. Clamp the number of
+        // milliseconds to the allowed range.
+        let millis = usize::max(timeout.as_millis().try_into().unwrap_or(usize::MAX), 1);
+
+        let was_timeout = blocking_scalar(
+            ticktimer_server(),
+            TicktimerScalar::WaitForCondition(self.index(), millis).into(),
+        )
+        .expect("failed to send WaitForCondition command")[0]
+            != 0;
+
+        let state = self.state.swap(EMPTY, Acquire);
+        if was_timeout && state == NOTIFIED {
+            // The state was set to NOTIFIED after we returned from the wait
+            // but before we reset the state. Therefore, a wakeup is on its
+            // way, which we need to consume here.
+            // NOTICE: this is a priority hole.
+            blocking_scalar(
+                ticktimer_server(),
+                TicktimerScalar::WaitForCondition(self.index(), 0).into(),
+            )
+            .expect("failed to send WaitForCondition command");
+        }
+    }
+
+    pub fn unpark(self: Pin<&Self>) {
+        let state = self.state.swap(NOTIFIED, Release);
+        if state == PARKED {
+            // The thread is parked, wake it up.
+            blocking_scalar(
+                ticktimer_server(),
+                TicktimerScalar::NotifyCondition(self.index(), 1).into(),
+            )
+            .expect("failed to send NotifyCondition command");
+        }
+    }
+}
+
+impl Drop for Parker {
+    fn drop(&mut self) {
+        scalar(ticktimer_server(), TicktimerScalar::FreeCondition(self.index()).into()).ok();
+    }
+}