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Mark-Simulacrum · Mark-Simulacrum · commit 97aca5f6caea · 2022-08-11T10:15:44.000-04:00
diff --git a/posts/2022-08-11-Rust-1.63.0.md b/posts/2022-08-11-Rust-1.63.0.md
@@ -94,11 +94,35 @@ We recommend that new APIs use these types instead of the previous type aliases
 [`BorrowedFd`]: https://doc.rust-lang.org/stable/std/os/unix/io/struct.BorrowedFd.html
 [`OwnedFd`]: https://doc.rust-lang.org/stable/std/os/unix/io/struct.OwnedFd.html
 
+### `const` Mutex, RwLock, Condvar initialization
+
+The [`Condvar::new`], [`Mutex::new`], and [`RwLock::new`] functions are now
+callable in `const` contexts, which allows avoiding the use of crates like
+`lazy_static` for creating global statics with `Mutex`, `RwLock`, or `Condvar`
+values. This builds on the [work in 1.62] to enable thinner and faster mutexes
+on Linux.
+
+[work in 1.62]: https://blog.rust-lang.org/2022/06/30/Rust-1.62.0.html#thinner-faster-mutexes-on-linux
+
 ### Turbofish for generics in functions with `impl Trait`
 
-The turbofish notation (`foo::<u32>()`) can be used to specify the types for explicit type
-parameters (`fn foo<T: Copy>`) even when `impl Trait` is used in the argument types.
-Specifying the type of an `impl Trait` argument via turbofish is still not possible.
+For a function signature like `fn foo<T>(value: T, f: impl FnOnce())`, it was an
+error to specify the concrete type of `T` via turbofish: `foo::<u32>(3, || {})`
+would fail with:
+
+```text
+error[E0632]: cannot provide explicit generic arguments when `impl Trait` is used in argument position
+ --> src/lib.rs:4:11
+  |
+4 |     foo::<u32>(3, 3);
+  |           ^^^ explicit generic argument not allowed
+  |
+  = note: see issue #83701 <https://github.com/rust-lang/rust/issues/83701> for more information
+```
+
+In 1.63, this restriction is relaxed, and the explicit type of the generic can be specified.
+However, the `impl Trait` parameter, despite desugaring to a generic, remains
+opaque and cannot be specified via turbofish.
 
 ### Non-lexical lifetimes migration complete
 
