From 33339e46ce170aaf93e109e129524ea593655d5f Mon Sep 17 00:00:00 2001
From: Jim Blandy <jimb@red-bean.com>
Date: Wed, 29 Nov 2023 18:28:50 -0800
Subject: [PATCH] [naga wgsl-in] Drop spanless labels from front-end error
 messages.

When a label in a WGSL front end error has an undefined span, omit the
label from the error message. This is not great, but because of the
way Naga IR represents local variable references it is hard to get the
right span, and omitting the label better than panicking in `unwrap`,
since the error message has a general message anyway.
---
 naga/src/front/wgsl/error.rs |  6 +++---
 naga/tests/wgsl_errors.rs    | 19 +++++++++++++++++++
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/naga/src/front/wgsl/error.rs b/naga/src/front/wgsl/error.rs
index dc10124680..f2db433e81 100644
--- a/naga/src/front/wgsl/error.rs
+++ b/naga/src/front/wgsl/error.rs
@@ -34,9 +34,9 @@ impl ParseError {
             .with_labels(
                 self.labels
                     .iter()
-                    .map(|label| {
-                        Label::primary((), label.0.to_range().unwrap())
-                            .with_message(label.1.to_string())
+                    .filter_map(|label| label.0.to_range().map(|range| (label, range)))
+                    .map(|(label, range)| {
+                        Label::primary((), range).with_message(label.1.to_string())
                     })
                     .collect(),
             )
diff --git a/naga/tests/wgsl_errors.rs b/naga/tests/wgsl_errors.rs
index b74f805f0d..c761ad361e 100644
--- a/naga/tests/wgsl_errors.rs
+++ b/naga/tests/wgsl_errors.rs
@@ -1984,6 +1984,25 @@ fn function_param_redefinition_as_local() {
     )
 }
 
+#[test]
+fn constructor_type_error_span() {
+    check(
+        "
+        fn unfortunate() {
+            var i: i32;
+            var a: array<f32, 1> = array<f32, 1>(i);
+        }
+    ",
+        r###"error: automatic conversions cannot convert `i32` to `f32`
+  ┌─ wgsl:4:36
+  │
+4 │             var a: array<f32, 1> = array<f32, 1>(i);
+  │                                    ^^^^^^^^^^^^^^^^ a value of type f32 is required here
+
+"###,
+    )
+}
+
 #[test]
 fn binding_array_local() {
     check_validation! {