Expect *.txt instead of - for the debug output of the converter

README.md

@@ -37,7 +37,7 @@ DOT (GraphViz)  | :ok:               | dot-out  | Not a shading language |
 Naga includes a default binary target, which allows to test the conversion of different code paths.
 ```bash
 cargo run --features wgsl-in -- my_shader.wgsl # validate only
-cargo run --features spv-in -- my_shader.spv - # dump the IR module to debug output
+cargo run --features spv-in -- my_shader.spv my_shader.txt # dump the IR module into a file
 cargo run --features spv-in,msl-out -- my_shader.spv my_shader.metal --flow-dir flow-dir # convert the SPV to Metal, also dump the SPIR-V flow graph to `flow-dir`
 cargo run --features wgsl-in,glsl-out -- my_shader.wgsl my_shader.vert --profile es310 # convert the WGSL to GLSL vertex stage under ES 3.20 profile
 ```

bin/naga.rs

@@ -199,14 +199,6 @@ fn main() {
             }
         }
     };
-    if output_path == "-" {
-        println!("{:#?}", module);
-        if let Some(info) = info {
-            println!();
-            println!("{:#?}", info);
-        }
-        return;
-    }
 
     match Path::new(output_path)
         .extension()
@@ -214,6 +206,15 @@ fn main() {
         .to_str()
         .unwrap()
     {
+        "txt" => {
+            use std::io::Write;
+            let mut file = fs::File::create(output_path).unwrap();
+            writeln!(file, "{:#?}", module).unwrap();
+            if let Some(info) = info {
+                writeln!(file).unwrap();
+                writeln!(file, "{:#?}", info).unwrap();
+            }
+        }
         #[cfg(feature = "msl-out")]
         "metal" => {
             use naga::back::msl;