Fixes crash when there's a missing texture argument (#6486)

CHANGELOG.md

@@ -64,6 +64,10 @@ Bottom level categories:
 
 ### Bug Fixes
 
+#### Naga
+
+- Fix crash when a texture argument is missing. By @aedm in [#6486](https://github.com/gfx-rs/wgpu/pull/6486)
+
 #### General
 
 - Ensure that `Features::TIMESTAMP_QUERY` is set when using timestamp writes in render and compute passes. By @ErichDonGubler in [#6497](https://github.com/gfx-rs/wgpu/pull/6497).

naga/src/valid/analyzer.rs

@@ -421,7 +421,10 @@ impl FunctionInfo {
             let image_storage = match sampling.image {
                 GlobalOrArgument::Global(var) => GlobalOrArgument::Global(var),
                 GlobalOrArgument::Argument(i) => {
-                    let handle = arguments[i as usize];
+                    let Some(handle) = arguments.get(i as usize).cloned() else {
+                        // Argument count mismatch, will be reported later by validate_call
+                        break;
+                    };
                     GlobalOrArgument::from_expression(expression_arena, handle).map_err(
                         |source| {
                             FunctionError::Expression { handle, source }
@@ -434,7 +437,10 @@ impl FunctionInfo {
             let sampler_storage = match sampling.sampler {
                 GlobalOrArgument::Global(var) => GlobalOrArgument::Global(var),
                 GlobalOrArgument::Argument(i) => {
-                    let handle = arguments[i as usize];
+                    let Some(handle) = arguments.get(i as usize).cloned() else {
+                        // Argument count mismatch, will be reported later by validate_call
+                        break;
+                    };
                     GlobalOrArgument::from_expression(expression_arena, handle).map_err(
                         |source| {
                             FunctionError::Expression { handle, source }

naga/tests/validation.rs

@@ -606,3 +606,40 @@ fn binding_arrays_cannot_hold_scalars() {
 
     assert!(t.validator.validate(&t.module).is_err());
 }
+
+#[cfg(feature = "wgsl-in")]
+#[test]
+fn validation_error_messages() {
+    let cases = [(
+        r#"@group(0) @binding(0) var my_sampler: sampler;
+
+                fn foo(tex: texture_2d<f32>) -> vec4<f32> {
+                    return textureSampleLevel(tex, my_sampler, vec2f(0, 0), 0.0);
+                }
+
+                fn main() {
+                    foo();
+                }
+            "#,
+        "\
+error: Function [1] 'main' is invalid
+  ┌─ wgsl:7:17
+  │  \n7 │ ╭                 fn main() {
+8 │ │                     foo();
+  │ │                     ^^^^ invalid function call
+  │ ╰──────────────────────────^ naga::Function [1]
+  │  \n  = Call to [0] is invalid
+  = Requires 1 arguments, but 0 are provided
+
+",
+    )];
+
+    for (source, expected_err) in cases {
+        let module = naga::front::wgsl::parse_str(source).unwrap();
+        let err = valid::Validator::new(Default::default(), valid::Capabilities::all())
+            .validate_no_overrides(&module)
+            .expect_err("module should be invalid");
+        println!("{}", err.emit_to_string(source));
+        assert_eq!(err.emit_to_string(source), expected_err);
+    }
+}