add cli arg to choose metal version

CHANGELOG.md

@@ -126,6 +126,10 @@ By @cwfitzgerald in [#5325](https://github.com/gfx-rs/wgpu/pull/5325).
 - Cache the sample count to keep `get_texture_format_features` cheap. By @Dinnerbone in [#5346](https://github.com/gfx-rs/wgpu/pull/5346)
 - Mark `DEPTH32FLOAT_STENCIL8` as supported in GLES. By @Dinnerbone in [#5370](https://github.com/gfx-rs/wgpu/pull/5370)
 
+#### Naga
+
+- Allow user to select which MSL version to use via `--metal-version` with Naga CLI. By @pcleavelin in [#5392](https://github.com/gfx-rs/wgpu/pull/5392)
+
 ### Bug Fixes
 
 #### General

naga-cli/src/bin/naga.rs

@@ -62,6 +62,10 @@ struct Args {
     #[argh(option)]
     shader_model: Option<ShaderModelArg>,
 
+    /// the metal version to use, for example, 1.0, 1.1, 1.2, etc.
+    #[argh(option)]
+    metal_version: Option<MslVersionArg>,
+
     /// if the selected frontends/backends support coordinate space conversions,
     /// disable them
     #[argh(switch)]
@@ -174,6 +178,30 @@ impl FromStr for GlslProfileArg {
     }
 }
 
+/// Newtype so we can implement [`FromStr`] for a Metal Language Version.
+#[derive(Clone, Debug)]
+struct MslVersionArg((u8, u8));
+
+impl FromStr for MslVersionArg {
+    type Err = String;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let mut iter = s.split('.');
+
+        let check_value = |iter: &mut core::str::Split<_>| {
+            iter.next()
+                .ok_or_else(|| format!("Invalid value for --metal-version: {s}"))?
+                .parse::<u8>()
+                .map_err(|err| format!("Invalid value for --metal-version: '{s}': {err}"))
+        };
+
+        let major = check_value(&mut iter)?;
+        let minor = check_value(&mut iter)?;
+
+        Ok(Self((major, minor)))
+    }
+}
+
 #[derive(Default)]
 struct Parameters<'a> {
     validation_flags: naga::valid::ValidationFlags,
@@ -287,6 +315,9 @@ fn run() -> Result<(), Box<dyn std::error::Error>> {
     if let Some(ref model) = args.shader_model {
         params.hlsl.shader_model = model.0;
     }
+    if let Some(ref version) = args.metal_version {
+        params.msl.lang_version = version.0;
+    }
     params.keep_coordinate_space = args.keep_coordinate_space;
 
     params.dot.cfg_only = args.dot_cfg_only;