Add CFRetained

Add a Retained-like pointer for CoreFoundation-like types.

Part of #556.

crates/header-translator/src/rust_type.rs

@@ -1418,6 +1418,14 @@ impl Ty {
         }
     }
 
+    pub(crate) fn is_cf_type(&self) -> bool {
+        if let Self::TypeDef { is_cf, .. } = self {
+            *is_cf
+        } else {
+            false
+        }
+    }
+
     pub(crate) fn is_objc_bool(&self) -> bool {
         match self {
             Self::Primitive(Primitive::ObjcBool) => true,

crates/header-translator/src/stmt.rs

@@ -1586,6 +1586,29 @@ impl Stmt {
                     _ => error!("unknown"),
                 });
 
+                // Don't map `CFRetain`, `CFRelease`, `CFAutorelease`, as well
+                // as custom ones like as `CGColorRelease`.
+                //
+                // Same as what Swift does:
+                // <https://github.com/swiftlang/swift/blob/swift-6.0.3-RELEASE/lib/ClangImporter/ImportDecl.cpp#L8435-L8452>
+                //
+                // Users can achieve (almost) the same by using `CFRetained`
+                // and `ManuallyDrop`, and this is clearer and safer.
+                //
+                // Besides, these do not have the necessary memory management
+                // attributes (cf_consumed/cf_returns_retained), and as such
+                // cannot be mapped correctly without extra hacks.
+                if id.name.ends_with("Retain")
+                    || id.name.ends_with("Release")
+                    || id.name.ends_with("Autorelease")
+                {
+                    if let Some((_, first_arg_ty)) = arguments.first() {
+                        if first_arg_ty.is_cf_type() {
+                            return vec![];
+                        }
+                    }
+                }
+
                 let body = if entity.is_inline_function() {
                     Some(())
                 } else {

crates/objc2/src/rc/retained_forwarding_impls.rs

@@ -1,19 +1,20 @@
-//! Trivial forwarding impls on `Retained`.
+//! Trivial forwarding impls on `Retained`-like types.
 //!
-//! Kept here to keep `id.rs` free from this boilerplate.
+//! Kept here to keep `retained.rs` free from this boilerplate, and to allow
+//! re-use in `objc2-core-foundation` (this file is symlinked there as well).
 
 #![forbid(unsafe_code)]
 
-use alloc::borrow;
-use alloc::string::String;
-use alloc::vec::Vec;
+use core::borrow::Borrow;
 use core::cmp::Ordering;
 use core::fmt;
 use core::future::Future;
 use core::hash;
 use core::pin::Pin;
 use core::task::{Context, Poll};
+#[cfg(feature = "std")] // TODO: Use core::error::Error once 1.81 is in MSRV
 use std::error::Error;
+#[cfg(feature = "std")]
 use std::io;
 
 use super::Retained;
@@ -206,7 +207,7 @@ where
     }
 }
 
-impl<T: ?Sized> borrow::Borrow<T> for Retained<T> {
+impl<T: ?Sized> Borrow<T> for Retained<T> {
     fn borrow(&self) -> &T {
         // Auto-derefs
         self
@@ -226,12 +227,14 @@ impl<T: ?Sized + AsRef<U>, U: ?Sized> AsRef<U> for Retained<T> {
     }
 }
 
+#[cfg(feature = "std")]
 impl<T: ?Sized + Error> Error for Retained<T> {
     fn source(&self) -> Option<&(dyn Error + 'static)> {
         (**self).source()
     }
 }
 
+#[cfg(feature = "std")]
 impl<T: ?Sized> io::Read for Retained<T>
 where
     for<'a> &'a T: io::Read,
@@ -247,12 +250,12 @@ where
     }
 
     #[inline]
-    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
+    fn read_to_end(&mut self, buf: &mut std::vec::Vec<u8>) -> io::Result<usize> {
         (&**self).read_to_end(buf)
     }
 
     #[inline]
-    fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
+    fn read_to_string(&mut self, buf: &mut std::string::String) -> io::Result<usize> {
         (&**self).read_to_string(buf)
     }
 
@@ -262,6 +265,7 @@ where
     }
 }
 
+#[cfg(feature = "std")]
 impl<'a, T: ?Sized> io::Read for &'a Retained<T>
 where
     &'a T: io::Read,
@@ -277,12 +281,12 @@ where
     }
 
     #[inline]
-    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
+    fn read_to_end(&mut self, buf: &mut std::vec::Vec<u8>) -> io::Result<usize> {
         (&***self).read_to_end(buf)
     }
 
     #[inline]
-    fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
+    fn read_to_string(&mut self, buf: &mut std::string::String) -> io::Result<usize> {
         (&***self).read_to_string(buf)
     }
 
@@ -292,6 +296,7 @@ where
     }
 }
 
+#[cfg(feature = "std")]
 impl<T: ?Sized> io::Write for Retained<T>
 where
     for<'a> &'a T: io::Write,
@@ -322,6 +327,7 @@ where
     }
 }
 
+#[cfg(feature = "std")]
 impl<'a, T: ?Sized> io::Write for &'a Retained<T>
 where
     &'a T: io::Write,
@@ -352,6 +358,7 @@ where
     }
 }
 
+#[cfg(feature = "std")]
 impl<T: ?Sized> io::Seek for Retained<T>
 where
     for<'a> &'a T: io::Seek,
@@ -367,6 +374,7 @@ where
     }
 }
 
+#[cfg(feature = "std")]
 impl<'a, T: ?Sized> io::Seek for &'a Retained<T>
 where
     &'a T: io::Seek,

framework-crates/objc2-core-foundation/Cargo.modified.toml

@@ -0,0 +1,3 @@
+[features]
+# Uses the nightly derive_coerce_pointee feature to make conversions more ergonomic.
+unstable-coerce-pointee = []

framework-crates/objc2-core-foundation/src/base.rs

@@ -115,3 +115,6 @@ impl hash::Hash for CFType {
 }
 
 crate::__cf_type_objc2!(CFType, crate::__cf_macro_helpers::Encoding::Void);
+
+// NOTE: impl AsRef<CFType> for AnyObject would probably not be valid, since
+// not all Objective-C objects can be used as CoreFoundation objects (?)

framework-crates/objc2-core-foundation/src/lib.rs

@@ -5,6 +5,7 @@
 //! [apple-doc]: https://developer.apple.com/documentation/corefoundation/
 //! [framework-crates]: https://docs.rs/objc2/latest/objc2/topics/about_generated/index.html
 #![no_std]
+#![cfg_attr(feature = "unstable-coerce-pointee", feature(derive_coerce_pointee))]
 #![cfg_attr(docsrs, feature(doc_auto_cfg))]
 // Update in Cargo.toml as well.
 #![doc(html_root_url = "https://docs.rs/objc2-core-foundation/0.2.2")]
@@ -25,6 +26,8 @@ mod cf_type;
 mod generated;
 #[cfg(feature = "CFCGTypes")]
 mod geometry;
+mod retained;
+mod type_traits;
 
 #[cfg(feature = "CFBase")]
 pub use self::base::*;
@@ -34,6 +37,8 @@ pub use self::bundle::CFBundleRefNum;
 pub use self::generated::*;
 #[cfg(feature = "CFCGTypes")]
 pub use self::geometry::*;
+pub use self::retained::CFRetained;
+pub use self::type_traits::Type;
 
 // MacTypes.h
 #[allow(dead_code)]