From 16f012bc9327b23345b6feed754204acb6df6beb Mon Sep 17 00:00:00 2001
From: Erich Gubler <erichdongubler@gmail.com>
Date: Wed, 30 Oct 2024 15:34:54 -0700
Subject: [PATCH] fix(naga-cli): allow output files with `--stdin-file-path`

---
 CHANGELOG.md             |  5 +++--
 naga-cli/src/bin/naga.rs | 16 +++++++++-------
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index b3999f0cfa..829f0d9b15 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -40,11 +40,12 @@ Bottom level categories:
 
 ## Unreleased
 
-## New Features
+### New Features
 
-### Naga
+#### Naga
 
 - Parse `diagnostic(…)` directives, but don't implement any triggering rules yet. By @ErichDonGubler in [#6456](https://github.com/gfx-rs/wgpu/pull/6456).
+- Fix an issue where `naga` CLI would incorrectly skip the first positional argument when `--stdin-file-path` was specified. By @ErichDonGubler in [#6480](https://github.com/gfx-rs/wgpu/pull/6480).
 
 ### Changes
 
diff --git a/naga-cli/src/bin/naga.rs b/naga-cli/src/bin/naga.rs
index 6523b2102d..e7d007d018 100644
--- a/naga-cli/src/bin/naga.rs
+++ b/naga-cli/src/bin/naga.rs
@@ -451,13 +451,15 @@ fn run() -> anyhow::Result<()> {
         return bulk_validate(args, &params);
     }
 
-    let (input_path, input) = if let Some(path) = args.files.first() {
-        let path = Path::new(path);
-        (path, fs::read(path)?)
-    } else if let Some(path) = &args.stdin_file_path {
+    let mut files = args.files.iter();
+
+    let (input_path, input) = if let Some(path) = args.stdin_file_path.as_ref() {
         let mut input = vec![];
         std::io::stdin().lock().read_to_end(&mut input)?;
         (Path::new(path), input)
+    } else if let Some(path) = files.next() {
+        let path = Path::new(path);
+        (path, fs::read(path)?)
     } else {
         return Err(CliError("Input file path is not specified").into());
     };
@@ -492,12 +494,12 @@ fn run() -> anyhow::Result<()> {
         }
     }
 
-    let output_paths = args.files.get(1..).unwrap_or(&[]);
+    let output_paths = files;
 
     // Decide which capabilities our output formats can support.
     let validation_caps =
         output_paths
-            .iter()
+            .clone()
             .fold(naga::valid::Capabilities::all(), |caps, path| {
                 use naga::valid::Capabilities as C;
                 let missing = match Path::new(path).extension().and_then(|ex| ex.to_str()) {
@@ -567,7 +569,7 @@ fn run() -> anyhow::Result<()> {
     //
     // If the user asked for output, don't stop: some output formats (".txt",
     // ".dot", ".bin") can be generated even without a `ModuleInfo`.
-    if output_paths.is_empty() {
+    if output_paths.clone().next().is_none() {
         if info.is_some() {
             println!("Validation successful");
             return Ok(());