From 5d9c276c827e3c85da36251f1b6904733f31c6c8 Mon Sep 17 00:00:00 2001
From: Mikko Lehtonen <scoopr@iki.fi>
Date: Wed, 4 Aug 2021 00:27:34 +0300
Subject: [PATCH] Include naga diagnostic in the parse error (#1760)

Wraps the Naga's `ParseError` with `NagaParseError` type, that uses the
Naga's full error formatting for its `Display` impl, including shader
source.
---
 wgpu-core/src/device/mod.rs |  7 ++++++-
 wgpu-core/src/pipeline.rs   | 17 ++++++++++++++++-
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/wgpu-core/src/device/mod.rs b/wgpu-core/src/device/mod.rs
index 9f8433db9b..6f5e999399 100644
--- a/wgpu-core/src/device/mod.rs
+++ b/wgpu-core/src/device/mod.rs
@@ -895,7 +895,12 @@ impl<A: HalApi> Device<A> {
                     Ok(module) => module,
                     Err(err) => {
                         log::error!("Failed to parse WGSL code for {:?}: {}", desc.label, err);
-                        return Err(pipeline::CreateShaderModuleError::Parsing);
+                        return Err(pipeline::CreateShaderModuleError::Parsing(
+                            pipeline::NagaParseError {
+                                shader_source: code.to_string(),
+                                error: err,
+                            },
+                        ));
                     }
                 }
             }
diff --git a/wgpu-core/src/pipeline.rs b/wgpu-core/src/pipeline.rs
index f090bffd8e..81d90ed711 100644
--- a/wgpu-core/src/pipeline.rs
+++ b/wgpu-core/src/pipeline.rs
@@ -44,10 +44,25 @@ impl<A: hal::Api> Resource for ShaderModule<A> {
     }
 }
 
+#[derive(Clone, Debug, Error)]
+pub struct NagaParseError {
+    pub shader_source: String,
+    pub error: naga::front::wgsl::ParseError,
+}
+impl std::fmt::Display for NagaParseError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "\nShader error:\n{}",
+            self.error.emit_to_string(&self.shader_source)
+        )
+    }
+}
+
 #[derive(Clone, Debug, Error)]
 pub enum CreateShaderModuleError {
     #[error("Failed to parse a shader")]
-    Parsing,
+    Parsing(#[from] NagaParseError),
     #[error("Failed to generate the backend-specific code")]
     Generation,
     #[error(transparent)]