Add post for 1.77

posts/2024-03-21-Rust-1.77.0.md

@@ -7,7 +7,7 @@ release: true
 
 The Rust team is happy to announce a new version of Rust, 1.77.0. Rust is a programming language empowering everyone to build reliable and efficient software.
 
-If you have a previous version of Rust installed via rustup, you can get 1.77.0 with:
+If you have a previous version of Rust installed via `rustup`, you can get 1.77.0 with:
 
 ```console
 $ rustup update stable
@@ -25,8 +25,27 @@ This release is relatively minor, but as always, even incremental improvements l
 
 Rust now supports C-string literals (`c"abc"`) which expand to a nul-byte
 terminated string in memory of type `&CStr`. This makes it easier to write code
-taking nul-terminated strings, with all of the relevant error checking (e.g.,
-lack of interior nul byte) implemented within the compiler.
+interoperating with foreign language interfaces which require nul-terminated
+strings, with all of the relevant error checking (e.g., lack of interior nul
+byte) performed at compile time.
+
+### Support for recursion in `async fn`
+
+async functions previously could not call themselves due to a compiler analysis
+limitation. In 1.77, that limitation has been lifted, so recursive calls are
+permitted so long as they use some form of indirection to avoid an infinite
+size for the state of the function.
+
+This means that code like this now works:
+
+```rust
+async fn fib(n : u32) -> u32 {
+   match n {
+       0 | 1 => 1,
+       _ => Box::pin(fib(n-1)).await + Box::pin(fib(n-2)).await
+   }
+}
+```
 
 ### `offset_of!`
 
@@ -35,32 +54,44 @@ byte offset of the relevant public field of a struct. This macro is most useful
 when the offset of a field is required without an existing instance of a type.
 Implementing such a macro is already possible on stable, but without an
 instance of the type the implementation would require tricky unsafe code which
-makes it easy to get into undefined behavior.
+makes it easy to accidentally introduce undefined behavior.
 
 Users can now access the offset of a public field with `offset_of!(StructName,
 field)`. This expands to a `usize` expression with the offset in bytes from the
 start of the struct.
 
-Note that the output of the macro is not typically stable across compiler
-versions or across platforms. See the macro's documentation for details on when the output can be relied on.
-
-[`offset_of!`]: https://doc.rust-lang.org/nightly/std/mem/macro.offset_of.html
+[`offset_of!`]: https://doc.rust-lang.org/stable/std/mem/macro.offset_of.html
 
 ### Enable strip in release profiles by default
 
 Cargo [profiles](https://doc.rust-lang.org/stable/cargo/reference/profiles.html)
-which do not enable [debug info](https://doc.rust-lang.org/stable/cargo/reference/profiles.html#debug) in
+which do not enable [debuginfo](https://doc.rust-lang.org/stable/cargo/reference/profiles.html#debug) in
 outputs (e.g., `debug = 0`) will enable `strip = "debuginfo"` by default.
 
 This is primarily needed because the (precompiled) standard library ships with
-debug info, which means that statically linked results would include the
+debuginfo, which means that statically linked results would include the
 debuginfo from the standard library even if the local compilations didn't
 explicitly request debuginfo.
 
 Users which do want debuginfo can explicitly enable it with the
 [debug](https://doc.rust-lang.org/stable/cargo/reference/profiles.html#debug)
 flag in the relevant Cargo profile.
 
+### Clippy adds a new `incompatible_msrv` lint
+
+The Rust project only supports the latest stable release of Rust. Some
+libraries aim to have an older minimum supported Rust version (MSRV), typically
+verifying this support by compiling in CI with an older release. However, when
+developing new code, it's convenient to use latest documentation and the latest
+toolchain with fixed bugs, performance improvements, and other improvements.
+This can make it easy to accidentally start using an API that's only available
+on newer versions of Rust.
+
+Clippy has added a new lint, [`incompatible_msrv`](https://rust-lang.github.io/rust-clippy/master/index.html#/incompatible_msrv),
+which will inform users if functionality being referenced is only available on
+newer versions than their
+[declared MSRV](https://github.com/rust-lang/rust-clippy/?tab=readme-ov-file#specifying-the-minimum-supported-rust-version).
+
 ### Stabilized APIs
 
 - [`array::each_ref`](https://doc.rust-lang.org/stable/std/primitive.array.html#method.each_ref)
@@ -86,7 +117,7 @@ flag in the relevant Cargo profile.
 
 ### Other changes
 
-Check out everything that changed in [Rust](https://github.com/rust-lang/rust/releases/tag/1.77.0), [Cargo](https://github.com/rust-lang/cargo/blob/master/CHANGELOG.md#cargo-177-2024-02-08), and [Clippy](https://github.com/rust-lang/rust-clippy/blob/master/CHANGELOG.md#rust-177).
+Check out everything that changed in [Rust](https://github.com/rust-lang/rust/releases/tag/1.77.0), [Cargo](https://github.com/rust-lang/cargo/blob/master/CHANGELOG.md#cargo-177-2024-03-21), and [Clippy](https://github.com/rust-lang/rust-clippy/blob/master/CHANGELOG.md#rust-177).
 
 ## Contributors to 1.77.0