Cherry-pick relevant parts of 9bd26ee for objc2 v0.6.4

And add a changelog entry for it.

Author: madsmtm

crates/objc2/CHANGELOG.md

@@ -6,6 +6,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## Unreleased - YYYY-MM-DD
 
+## Added
+* Added support for the unstable `darwin_objc` feature.
+
 
 ## [0.6.3] - 2025-10-04
 [0.6.3]: https://github.com/madsmtm/objc2/compare/objc2-0.6.2...objc2-0.6.3

crates/objc2/Cargo.toml

@@ -69,7 +69,7 @@ disable-encoding-assertions = []
 # no longer required.
 verify = []
 
-# Make the `sel!` macro look up the selector statically.
+# Make the `sel!`/`class!` macro look up the item statically.
 #
 # The plan is to enable this by default, but right now we are uncertain of
 # its stability, and it might need significant changes before being fully
@@ -82,6 +82,9 @@ unstable-static-sel-inlined = ["unstable-static-sel"]
 unstable-static-class = ["dep:objc2-proc-macros"]
 unstable-static-class-inlined = ["unstable-static-class"]
 
+# Augment the above with the nightly `darwin_objc` feature.
+unstable-darwin-objc = []
+
 # Uses nightly features to make autorelease pools fully sound
 unstable-autoreleasesafe = []
 

crates/objc2/src/__macro_helpers/common_selectors.rs

@@ -11,30 +11,30 @@ use crate::runtime::Sel;
 
 #[inline]
 pub fn alloc_sel() -> Sel {
-    __sel_inner!("alloc\0", "alloc")
+    __sel_inner!("alloc", "alloc")
 }
 
 #[inline]
 pub fn init_sel() -> Sel {
-    __sel_inner!("init\0", "init")
+    __sel_inner!("init", "init")
 }
 
 #[inline]
 pub fn new_sel() -> Sel {
-    __sel_inner!("new\0", "new")
+    __sel_inner!("new", "new")
 }
 
 #[inline]
 pub fn dealloc_sel() -> Sel {
-    __sel_inner!("dealloc\0", "dealloc")
+    __sel_inner!("dealloc", "dealloc")
 }
 
 /// An undocumented selector called by the Objective-C runtime when
 /// initializing instance variables.
 #[inline]
 #[allow(dead_code)] // May be useful in the future
 fn cxx_construct_sel() -> Sel {
-    __sel_inner!(".cxx_construct\0", ".cxx_construct")
+    __sel_inner!(".cxx_construct", ".cxx_construct")
 }
 
 /// Objective-C runtimes call `.cxx_destruct` as part of the final `dealloc`
@@ -71,7 +71,7 @@ fn cxx_construct_sel() -> Sel {
 #[inline]
 #[allow(dead_code)] // May be useful in the future
 fn cxx_destruct_sel() -> Sel {
-    __sel_inner!(".cxx_destruct\0", ".cxx_destruct")
+    __sel_inner!(".cxx_destruct", ".cxx_destruct")
 }
 
 #[cfg(test)]

crates/objc2/src/__macro_helpers/mod.rs

@@ -14,6 +14,9 @@ pub use core::{compile_error, concat, env, module_path, panic, stringify};
 // TODO: Use `core::cell::LazyCell`
 pub use std::sync::Once;
 
+#[cfg(feature = "unstable-darwin-objc")]
+pub use core::os::darwin::objc as core_darwin_objc;
+
 mod cache;
 mod class;
 mod common_selectors;

crates/objc2/src/lib.rs

@@ -104,6 +104,7 @@
 //! [#203]: https://github.com/madsmtm/objc2/issues/203
 
 #![no_std]
+#![cfg_attr(feature = "unstable-darwin-objc", feature(darwin_objc))]
 #![cfg_attr(
     feature = "unstable-autoreleasesafe",
     feature(negative_impls, auto_traits)

crates/objc2/src/macros/mod.rs

@@ -139,13 +139,26 @@ macro_rules! __class_inner {
 /// - runtime, causing UB (unlikely)
 ///
 /// The `"unstable-static-sel-inlined"` feature is the even more extreme
-/// version - it yields the best performance and is closest to real
+/// version - it yield better performance and is closer to real
 /// Objective-C code, but probably won't work unless your code and its
 /// inlining is written in a very certain way.
 ///
 /// Enabling LTO greatly increases the chance that these features work.
 ///
+/// On Apple/Darwin targets, these limitations can be overcome with the
+/// `"unstable-darwin-objc"` feature which uses the nightly-only `darwin_objc`
+/// language feature. This experimental language feature implements the
+/// Objective-C static selector ABI directly in the Rust compiler and should
+/// work in more if not all cases. Using `"unstable-darwin-objc"` requires
+/// `darwin_objc` to be enabled in every crate that uses this macro, which can
+/// be achieved in `objc2` crates by enabling their own
+/// `"unstable-darwin-objc"` features and in your own crates by adding
+/// `#![feature(darwin_objc)]`.
+///
+/// See [rust-lang/rust#145496] for the tracking issue for the feature.
+///
 /// [rust-lang/rust#53929]: https://github.com/rust-lang/rust/issues/53929
+/// [rust-lang/rust#145496]: https://github.com/rust-lang/rust/issues/145496
 ///
 ///
 /// # Examples
@@ -267,9 +280,9 @@ macro_rules! __sel_helper {
     // Base-case
     {
         ($($parsed_sel:tt)*)
-    } => ({
+    } => {
         $crate::__sel_data!($($parsed_sel)*)
-    });
+    };
     // Single identifier
     {
         ()
@@ -309,7 +322,6 @@ macro_rules! __sel_data {
         $crate::__macro_helpers::concat!(
             $crate::__macro_helpers::stringify!($first),
             $(':', $($($crate::__macro_helpers::stringify!($rest),)? ':',)*)?
-            '\0',
         )
     };
 }
@@ -323,7 +335,7 @@ macro_rules! __sel_inner {
             $crate::__macro_helpers::CachedSel::new();
         #[allow(unused_unsafe)]
         unsafe {
-            CACHED_SEL.get($data)
+            CACHED_SEL.get($crate::__macro_helpers::concat!($data, '\0'))
         }
     }};
 }
@@ -405,7 +417,7 @@ macro_rules! __statics_sel {
         ($data:expr)
         ($hash:expr)
     } => {
-        const X: &[$crate::__macro_helpers::u8] = $data.as_bytes();
+        const X: &[$crate::__macro_helpers::u8] = $crate::__macro_helpers::concat!($data, '\0').as_bytes();
 
         /// Clang marks this with LLVM's `unnamed_addr`.
         /// See rust-lang/rust#18297
@@ -559,11 +571,26 @@ macro_rules! __statics_class {
     }
 }
 
+#[doc(hidden)]
+#[macro_export]
+#[cfg(all(feature = "unstable-static-sel", feature = "unstable-darwin-objc"))]
+macro_rules! __sel_inner {
+    ($data:expr, $_hash:expr) => {{
+        let ptr = $crate::__macro_helpers::core_darwin_objc::selector!($data);
+        let ptr = ptr.cast_const().cast::<$crate::__macro_helpers::u8>();
+        #[allow(unused_unsafe)]
+        unsafe {
+            $crate::runtime::Sel::__internal_from_ptr(ptr)
+        }
+    }};
+}
+
 #[doc(hidden)]
 #[macro_export]
 #[cfg(all(
     feature = "unstable-static-sel",
-    not(feature = "unstable-static-sel-inlined")
+    not(feature = "unstable-darwin-objc"),
+    not(feature = "unstable-static-sel-inlined"),
 ))]
 macro_rules! __sel_inner {
     ($data:expr, $hash:expr) => {{
@@ -595,7 +622,11 @@ macro_rules! __sel_inner {
 
 #[doc(hidden)]
 #[macro_export]
-#[cfg(feature = "unstable-static-sel-inlined")]
+#[cfg(all(
+    feature = "unstable-static-sel",
+    not(feature = "unstable-darwin-objc"),
+    feature = "unstable-static-sel-inlined",
+))]
 macro_rules! __sel_inner {
     ($data:expr, $hash:expr) => {{
         $crate::__statics_sel! {
@@ -615,6 +646,24 @@ macro_rules! __sel_inner {
 #[macro_export]
 #[cfg(all(
     feature = "unstable-static-class",
+    feature = "unstable-darwin-objc",
+    not(feature = "gnustep-1-7"),
+))]
+macro_rules! __class_inner {
+    ($name:expr, $_hash:expr) => {{
+        let ptr = $crate::__macro_helpers::core_darwin_objc::class!($name);
+        let ptr = ptr.cast_const().cast::<$crate::runtime::AnyClass>();
+        #[allow(unused_unsafe)]
+        let r: &'static $crate::runtime::AnyClass = unsafe { &*ptr };
+        r
+    }};
+}
+
+#[doc(hidden)]
+#[macro_export]
+#[cfg(all(
+    feature = "unstable-static-class",
+    not(feature = "unstable-darwin-objc"),
     not(feature = "gnustep-1-7"),
     not(feature = "unstable-static-class-inlined")
 ))]
@@ -639,6 +688,7 @@ macro_rules! __class_inner {
 #[macro_export]
 #[cfg(all(
     feature = "unstable-static-class",
+    not(feature = "unstable-darwin-objc"),
     not(feature = "gnustep-1-7"),
     feature = "unstable-static-class-inlined"
 ))]