Merge branch '⬆️-nightly-2023-03-18' into 🦆

Author: yvt

Cargo.toml

@@ -1,3 +1,5 @@
+cargo-features = ["profile-rustflags"]
+
 [workspace]
 members = [
     "examples/basic",
@@ -117,3 +119,8 @@ rev = "2a74b62c26724ff9c67e4e3ad05378a1af53f195"
 
 [profile.release]
 debug = true
+
+# FIXME: Work-around for undefined symbol errors that occur with the
+# combination of `-Zbuild-std`, `opt-level = "s"`, and `lto = true`
+# <https://github.com/rust-lang/rust/issues/108853>
+rustflags = ["-Zshare-generics=off"]

doc/toolchain_limitations.md

@@ -106,7 +106,7 @@ type Alias<T> = Struct<{<T as Trait>::N}>;
 
 ### `[tag:const_for]` `for` loops are unusable in `const fn`
 
-Technically it's available under the compiler feature `const_for`, but the lack of essential trait implementations (e.g., `[ref:range_const_iterator]`, `[ref:const_slice_iter]`) and above all the inability of implementing `const Iterator` (`[ref:iterator_const_default]`) make it unusable.
+Technically it's available under the compiler feature `const_for`, but the lack of essential trait implementations (e.g., `[ref:range_const_iterator]`, `[ref:const_slice_iter]`) makes it unusable in many cases.
 
 
 ### `[tag:const_static_item_ref]` `const`s and `const fn`s can't refer to `static`s
@@ -430,23 +430,6 @@ const _: () = assert!(PartialEq::eq(&(A..A), &(A..A)));
 ```
 
 
-### `[tag:type_id_partial_eq]` `TypeId: !const PartialEq`
-
-The standard library doesn't provide a `const` trait implementation of `PartialEq` for `core::any::TypeId`.
-
-```rust
-use core::any::TypeId;
-assert!(TypeId::of::<()>() == TypeId::of::<()>());
-```
-
-```rust,compile_fail,E0277
-#![feature(const_type_id)]
-use core::any::TypeId;
-// error[E0277]: can't compare `TypeId` with `_` in const contexts
-const _: () = assert!(TypeId::of::<()>() == TypeId::of::<()>());
-```
-
-
 ### `[tag:range_const_iterator]` `Range<T>: !~const Iterator`
 
 The standard library doesn't provide a `const` trait implementation of `Range<T>: Iterator`.
@@ -466,25 +449,6 @@ const _: () = assert!(matches!((2..4).next(), Some(2)));
 ```
 
 
-### `[tag:iterator_const_default]` `Iterator` lack `#[const_trait]`
-
-```rust,compile_fail
-#![feature(const_trait_impl)]
-#![feature(const_mut_refs)]
-
-struct MyIterator;
-
-// error: const `impl` for trait `Iterator` which is not marked with `#[const_trait]`
-impl const Iterator for MyIterator {
-    type Item = u32;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        Some(42)
-    }
-}
-```
-
-
 ### `[tag:const_assert_eq]` `assert_eq!` and similar macros are unusable in `const fn`
 
 ```rust,compile_fail,E0015

rust-toolchain.toml

@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2023-01-10"
+channel = "nightly-2023-03-18"
 components = ["rustfmt", "rust-src", "clippy"]

src/r3_core/src/bag.rs

@@ -1,5 +1,5 @@
 //! A heterogeneous collection to store property values.
-use core::mem::transmute;
+use core::{any::TypeId, mem::transmute};
 
 /// A heterogeneous collection to store property values.
 #[const_trait]
@@ -88,40 +88,3 @@ mod private {
     impl<Head: 'static, Tail: ~const Bag> const Sealed for super::List<Head, Tail> {}
     impl<Left: ~const Bag, Right: ~const Bag> const Sealed for super::Either<Left, Right> {}
 }
-
-// `TypeId` doesn't implement `const PartialEq` [ref:type_id_partial_eq]
-/// A wrapper of [`core::any::TypeId`] that is usable in a constant context.
-struct TypeId {
-    inner: core::any::TypeId,
-}
-
-impl TypeId {
-    #[inline]
-    const fn of<T: 'static>() -> Self {
-        Self {
-            inner: core::any::TypeId::of::<T>(),
-        }
-    }
-
-    #[inline]
-    const fn eq(&self, other: &Self) -> bool {
-        // This relies on the implementation details of `TypeId`, but I think
-        // we're are okay judging by the fact that WebRender is doing the same
-        // <https://github.com/rust-lang/rust/pull/75923#issuecomment-683090745>
-        unsafe {
-            type TypeIdBytes = [u8; core::mem::size_of::<core::any::TypeId>()];
-            let x: TypeIdBytes = transmute(self.inner);
-            let y: TypeIdBytes = transmute(other.inner);
-            // Can't just do `x == y` due to [ref:array_const_partial_eq].
-            // A non-idiomatic loop must be used due to [ref:const_for].
-            let mut i = 0;
-            while i < x.len() {
-                if x[i] != y[i] {
-                    return false;
-                }
-                i += 1;
-            }
-            true
-        }
-    }
-}

src/r3_core/src/bind/sorter.rs

@@ -318,7 +318,7 @@ pub(super) const fn sort_bindings<Callback, SorterUseInfoList, VertexList>(
         End,
     }
 
-    impl const MyIterator for VertexIter<'_> {
+    impl const Iterator for VertexIter<'_> {
         type Item = Vertex;
 
         fn next(&mut self) -> Option<Self::Item> {
@@ -369,7 +369,7 @@ pub(super) const fn sort_bindings<Callback, SorterUseInfoList, VertexList>(
         End,
     }
 
-    impl<Callback> const MyIterator for SuccessorIter<'_, Callback>
+    impl<Callback> const Iterator for SuccessorIter<'_, Callback>
     where
         Callback: ~const SorterCallback,
     {
@@ -533,23 +533,14 @@ pub(super) const fn sort_bindings<Callback, SorterUseInfoList, VertexList>(
 // Helper traits
 // --------------------------------------------------------------------------
 
-// `const Iterator` is currently very hard to implement
-// [ref:iterator_const_default]
-/// An [`Iterator`][] usable in `const fn`.
-#[const_trait]
-trait MyIterator {
-    type Item;
-    fn next(&mut self) -> Option<Self::Item>;
-}
-
 #[const_trait]
 trait GraphAccess<VertexRef> {
-    type VertexIter<'a>: ~const MyIterator<Item = VertexRef> + ~const Destruct + 'a
+    type VertexIter<'a>: ~const Iterator<Item = VertexRef> + ~const Destruct + 'a
     where
         Self: 'a;
     fn vertices(&self) -> Self::VertexIter<'_>;
 
-    type SuccessorIter<'a>: ~const MyIterator<Item = VertexRef> + ~const Destruct + 'a
+    type SuccessorIter<'a>: ~const Iterator<Item = VertexRef> + ~const Destruct + 'a
     where
         Self: 'a;
     fn successors(&self, v: &VertexRef) -> Self::SuccessorIter<'_>;

src/r3_kernel/src/lib.rs

@@ -27,7 +27,6 @@
 #![feature(const_swap)]
 #![feature(never_type)] // `!`
 #![feature(decl_macro)]
-#![feature(pin_macro)]
 #![feature(doc_cfg)] // `#[doc(cfg(...))]`
 #![deny(unsafe_op_in_unsafe_fn)]
 #![cfg_attr(

src/r3_kernel/src/utils/ctz.rs

@@ -314,7 +314,7 @@ mod tests {
                         } else {
                             let low = i & 31;
                             let high = i >> 5;
-                            low | (high << (bits - 5))
+                            low | high.checked_shl((bits - 5) as u32).unwrap()
                         } as usize;
 
                         let got = $func(in_value);

src/r3_port_std/src/lib.rs

@@ -1,5 +1,4 @@
 #![feature(cfg_target_has_atomic)] // `#[cfg(target_has_atomic_load_store)]`
-#![feature(atomic_mut_ptr)]
 #![feature(thread_local)]
 #![feature(deadline_api)]
 #![feature(once_cell)]

src/r3_port_std/src/threading_windows.rs

@@ -91,7 +91,7 @@ pub fn park() {
         while token_count < 0 {
             unsafe {
                 synchapi::WaitOnAddress(
-                    token_count_cell.as_mut_ptr().cast(),    // location to watch
+                    token_count_cell.as_ptr().cast(),        // location to watch
                     addr_of!(token_count).cast_mut().cast(), // undesired value
                     std::mem::size_of::<isize>(),            // value size
                     INFINITE,                                // timeout
@@ -116,7 +116,7 @@ impl Thread {
         let _guard = self.data.remote_op_mutex.lock().unwrap();
         let token_count_cell = &self.data.token_count;
         if token_count_cell.fetch_add(1, Ordering::Relaxed) == -1 {
-            unsafe { synchapi::WakeByAddressAll(token_count_cell.as_mut_ptr().cast()) };
+            unsafe { synchapi::WakeByAddressAll(token_count_cell.as_ptr().cast()) };
             unsafe { processthreadsapi::ResumeThread(self.data.hthread) };
         }
     }
@@ -256,7 +256,7 @@ mod mutex {
             {
                 unsafe {
                     synchapi::WaitOnAddress(
-                        self.locked.as_mut_ptr().cast(),   // location to watch
+                        self.locked.as_ptr().cast(),       // location to watch
                         [true].as_ptr().cast_mut().cast(), // undesired value
                         std::mem::size_of::<bool>(),       // value size
                         INFINITE,                          // timeout
@@ -283,7 +283,7 @@ mod mutex {
         #[inline]
         fn drop(&mut self) {
             self.locked.store(false, Ordering::Release);
-            unsafe { synchapi::WakeByAddressSingle(self.locked.as_mut_ptr().cast()) };
+            unsafe { synchapi::WakeByAddressSingle(self.locked.as_ptr().cast()) };
         }
     }
 

src/r3_test_runner/src/main.rs

@@ -4,7 +4,6 @@
 #![feature(lint_reasons)]
 #![feature(decl_macro)] // `macro`
 #![feature(once_cell)]
-#![feature(pin_macro)] // `core::pin::pin!`
 #![warn(must_not_suspend)]
 use anyhow::{bail, Context};
 use clap::Parser;