added support for aarch64 ios simulator (#3783)

* added support for aarch64 ios simulator

* remove dependency on nightly feature

* fix missing newline at end of file

Author: geertbleyen

src/backend/metal/Cargo.toml

@@ -11,6 +11,7 @@ readme = "README.md"
 documentation = "https://docs.rs/gfx-backend-metal"
 workspace = "../../.."
 edition = "2018"
+build = "build/build.rs"
 
 [features]
 #TODO: add a feature to enable `profiling`, so that we can CI test it

src/backend/metal/build/build.rs

@@ -0,0 +1,6 @@
+fn main() {
+    println!(
+        "cargo:rustc-env=TARGET={}",
+        std::env::var("TARGET").unwrap()
+    );
+}

src/backend/metal/src/internal.rs

@@ -456,7 +456,11 @@ impl ServicePipes {
         let data = if cfg!(target_os = "macos") {
             &include_bytes!("./../shaders/gfx-shaders-macos.metallib")[..]
         } else if cfg!(target_arch = "aarch64") {
-            &include_bytes!("./../shaders/gfx-shaders-ios.metallib")[..]
+            if env!("TARGET") == "aarch64-apple-ios-sim" { 
+                &include_bytes!("./../shaders/gfx-shaders-ios-simulator.metallib")[..]
+            } else {
+                &include_bytes!("./../shaders/gfx-shaders-ios.metallib")[..]
+            }
         } else {
             &include_bytes!("./../shaders/gfx-shaders-ios-simulator.metallib")[..]
         };