Use unstable_static_encoding_str feature in objc2 and objc2-foundation

Author: madsmtm

objc2-foundation/Cargo.toml

@@ -23,7 +23,11 @@ default = ["block"]
 # Provided as a way to cut down on dependencies
 block = ["block2"]
 
+# Requires the `generic_const_exprs` feature
+unstable_static_encoding_str = ["objc2-encode/unstable_static_encoding_str", "objc2/unstable_static_encoding_str"]
+
 [dependencies]
 block2 = { path = "../block2", optional = true }
 objc2 = { path = "../objc2" }
 objc-sys = { path = "../objc-sys" }
+objc2-encode = { path = "../objc2-encode", optional = true }

objc2-foundation/src/value.rs

@@ -57,14 +57,16 @@ pub unsafe trait INSValue: INSObject {
     fn new(value: Self::Value) -> Id<Self, Self::Ownership> {
         let cls = Self::class();
         let bytes = &value as *const Self::Value as *const c_void;
+        #[cfg(not(feature = "unstable_static_encoding_str"))]
         let encoding = CString::new(Self::Value::ENCODING.to_string()).unwrap();
+        #[cfg(not(feature = "unstable_static_encoding_str"))]
+        let encoding_ptr = encoding.as_ptr();
+        #[cfg(feature = "unstable_static_encoding_str")]
+        let encoding_ptr =
+            <objc2_encode::EncodingHelper<Self::Value::ENCODING>>::ENCODING_CSTR.cast::<c_char>();
         unsafe {
             let obj: *mut Self = msg_send![cls, alloc];
-            let obj: *mut Self = msg_send![
-                obj,
-                initWithBytes: bytes,
-                objCType: encoding.as_ptr(),
-            ];
+            let obj: *mut Self = msg_send![obj, initWithBytes: bytes, objCType: encoding_ptr];
             Id::new(NonNull::new_unchecked(obj))
         }
     }

objc2/Cargo.toml

@@ -32,6 +32,9 @@ catch_all = ["exception"]
 verify_message = []
 unstable_autoreleasesafe = []
 
+# Requires the `generic_const_exprs` feature
+unstable_static_encoding_str = ["objc2-encode/unstable_static_encoding_str"]
+
 [dependencies]
 malloc_buf = "1.0"
 objc-sys = { path = "../objc-sys" }

objc2/src/declare.rs

@@ -243,17 +243,17 @@ impl ClassDecl {
     /// If the ivar wasn't successfully added.
     pub fn add_ivar<T: Encode>(&mut self, name: &str) {
         let c_name = CString::new(name).unwrap();
+        #[cfg(not(feature = "unstable_static_encoding_str"))]
         let encoding = CString::new(T::ENCODING.to_string()).unwrap();
+        #[cfg(not(feature = "unstable_static_encoding_str"))]
+        let encoding_ptr = encoding.as_ptr();
+        #[cfg(feature = "unstable_static_encoding_str")]
+        let encoding_ptr = <objc2_encode::EncodingHelper<T::ENCODING>>::ENCODING_CSTR
+            .cast::<std::os::raw::c_char>();
         let size = mem::size_of::<T>();
         let align = log2_align_of::<T>();
         let success = Bool::from_raw(unsafe {
-            runtime::class_addIvar(
-                self.cls as _,
-                c_name.as_ptr(),
-                size,
-                align,
-                encoding.as_ptr(),
-            )
+            runtime::class_addIvar(self.cls as _, c_name.as_ptr(), size, align, encoding_ptr)
         });
         assert!(success.is_true(), "Failed to add ivar {}", name);
     }