Naga(msl): Clear named expressions after writing each function (#4594)

This appears to match other backends, and fixes
fix the case where expressions which were named in earlier
functions are used in local variable declarations

CHANGELOG.md

@@ -44,11 +44,14 @@ For naga changelogs at or before v0.14.0. See [naga's changelog](naga/CHANGELOG.
 
 ### Bug Fixes
 
-
 #### WGL
 
 - Create a hidden window per `wgpu::Instance` instead of sharing a global one.
 
+#### Naga MSL-OUT
+
+- Fix issue where local variables were sometimes using variable names from previous functions.
+
 ## v0.18.0 (2023-10-25)
 
 ### Desktop OpenGL 3.3+ Support on Windows

naga/src/back/msl/writer.rs

@@ -3643,10 +3643,10 @@ impl<W: Write> Writer<W> {
                 writeln!(self.out, ";")?;
             }
 
-            self.named_expressions.clear();
             self.update_expressions_to_bake(fun, fun_info, &context.expression);
             self.put_block(back::Level(1), &fun.body, &context)?;
             writeln!(self.out, "}}")?;
+            self.named_expressions.clear();
         }
 
         let mut info = TranslationInfo {
@@ -4313,13 +4313,13 @@ impl<W: Write> Writer<W> {
                 writeln!(self.out, ";")?;
             }
 
-            self.named_expressions.clear();
             self.update_expressions_to_bake(fun, fun_info, &context.expression);
             self.put_block(back::Level(1), &fun.body, &context)?;
             writeln!(self.out, "}}")?;
             if ep_index + 1 != module.entry_points.len() {
                 writeln!(self.out)?;
             }
+            self.named_expressions.clear();
         }
 
         Ok(info)