From b35396bcd18ccbf1edb3d79c509c6cc5f5c9a784 Mon Sep 17 00:00:00 2001
From: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
Date: Wed, 22 Mar 2023 14:24:25 +0100
Subject: [PATCH 1/2] Validate shader location clashes

---
 wgpu-core/src/device/mod.rs | 8 +++++++-
 wgpu-core/src/pipeline.rs   | 2 ++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/wgpu-core/src/device/mod.rs b/wgpu-core/src/device/mod.rs
index f4413d1d3d..1b35d862e9 100644
--- a/wgpu-core/src/device/mod.rs
+++ b/wgpu-core/src/device/mod.rs
@@ -2806,10 +2806,16 @@ impl<A: HalApi> Device<A> {
                     self.require_features(wgt::Features::VERTEX_ATTRIBUTE_64BIT)?;
                 }
 
-                io.insert(
+                let previous = io.insert(
                     attribute.shader_location,
                     validation::InterfaceVar::vertex_attribute(attribute.format),
                 );
+
+                if previous.is_some() {
+                    return Err(pipeline::CreateRenderPipelineError::ShaderLocationClash(
+                        attribute.shader_location,
+                    ));
+                }
             }
             total_attributes += vb_state.attributes.len();
         }
diff --git a/wgpu-core/src/pipeline.rs b/wgpu-core/src/pipeline.rs
index cefeb97ba7..b46bd9fc25 100644
--- a/wgpu-core/src/pipeline.rs
+++ b/wgpu-core/src/pipeline.rs
@@ -352,6 +352,8 @@ pub enum CreateRenderPipelineError {
         location: wgt::ShaderLocation,
         offset: wgt::BufferAddress,
     },
+    #[error("Two or more attributes were assigned to the same shader lcoation {0}")]
+    ShaderLocationClash(u32),
     #[error("Strip index format was not set to None but to {strip_index_format:?} while using the non-strip topology {topology:?}")]
     StripIndexFormatForNonStripTopology {
         strip_index_format: Option<wgt::IndexFormat>,

From 6ec6030f224dcc6140a004e3c2193b10c1690b63 Mon Sep 17 00:00:00 2001
From: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
Date: Wed, 22 Mar 2023 14:27:43 +0100
Subject: [PATCH 2/2] Add line to changelog

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a3f09f7c45..e9cbb50e87 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -150,6 +150,7 @@ By @cwfitzgerald in [#3610](https://github.com/gfx-rs/wgpu/pull/3610).
 - `copyTextureToTexture` src/dst aspects must both refer to all aspects of src/dst format. By @teoxoy in [#3431](https://github.com/gfx-rs/wgpu/pull/3431)
 - Validate before extracting texture selectors. By @teoxoy in [#3487](https://github.com/gfx-rs/wgpu/pull/3487)
 - Fix fatal errors (those which panic even if an error handler is set) not including all of the details. By @kpreid in [#3563](https://github.com/gfx-rs/wgpu/pull/3563)
+- Validate shader location clashes. By @emilk in [#3613](https://github.com/gfx-rs/wgpu/pull/3613)
 
 #### Vulkan