Use unstable-static-encoding-str feature in objc2 and objc2-foundation

Author: madsmtm

objc2-foundation/Cargo.toml

@@ -23,10 +23,14 @@ 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", version = "=0.2.0-alpha.3", optional = true }
 objc2 = { path = "../objc2", version = "=0.3.0-alpha.6" }
 objc-sys = { path = "../objc-sys", version = "=0.2.0-alpha.1" }
+objc2-encode = { path = "../objc2-encode", optional = true }
 
 [package.metadata.docs.rs]
 default-target = "x86_64-apple-darwin"

objc2-foundation/src/value.rs

@@ -65,14 +65,13 @@ impl<T: 'static + Copy + Encode> NSValue<T> {
     pub fn new(value: T) -> Id<Self, Shared> {
         let cls = Self::class();
         let bytes = &value as *const T as *const c_void;
-        let encoding = CString::new(T::ENCODING.to_string()).unwrap();
+        #[cfg(not(feature = "unstable-static-encoding-str"))]
+        let encoding_ptr = CString::new(T::ENCODING.to_string()).unwrap().as_ptr();
+        #[cfg(feature = "unstable-static-encoding-str")]
+        let encoding_ptr = <objc2::encode::EncodingHelper<T>>::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(obj).unwrap()
         }
     }

objc2/Cargo.toml

@@ -40,6 +40,9 @@ malloc = ["malloc_buf"]
 # Uses nightly features to make AutoreleasePool zero-cost even in debug mode
 unstable_autoreleasesafe = []
 
+# Requires the `generic_const_exprs` feature
+unstable-static-encoding-str = ["objc2-encode/unstable-static-encoding-str"]
+
 [dependencies]
 malloc_buf = { version = "1.0", optional = true }
 objc-sys = { path = "../objc-sys", version = "=0.2.0-alpha.1" }

objc2/src/declare.rs

@@ -262,17 +262,15 @@ 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();
-        let encoding = CString::new(T::ENCODING.to_string()).unwrap();
+        #[cfg(not(feature = "unstable-static-encoding-str"))]
+        let encoding = CString::new(T::ENCODING.to_string()).unwrap().as_ptr();
+        #[cfg(feature = "unstable-static-encoding-str")]
+        let encoding_ptr =
+            <objc2_encode::EncodingHelper<T>>::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 {
-            ffi::class_addIvar(
-                self.as_ptr(),
-                c_name.as_ptr(),
-                size,
-                align,
-                encoding.as_ptr(),
-            )
+            ffi::class_addIvar(self.as_ptr(), c_name.as_ptr(), size, align, encoding_ptr)
         });
         assert!(success.as_bool(), "Failed to add ivar {}", name);
     }