Validate the number of color attachments in create_render_pipeline (#2913)

Author: nical

CHANGELOG.md

@@ -85,6 +85,7 @@ the same every time it is rendered, we now warn if it is missing.
 - Fix panics that occur when using `as_hal` functions when the hal generic type does not match the hub being looked up in by @i509VCB [#2871](https://github.com/gfx-rs/wgpu/pull/2871)
 - Add some validation in map_async by @nical in [#2876](https://github.com/gfx-rs/wgpu/pull/2876)
 - Fix bugs when mapping/unmapping zero-sized buffers and ranges by @nical in [#2877](https://github.com/gfx-rs/wgpu/pull/2877)
+- Validate the number of color attachments in `create_render_pipeline` by @nical in [#2913](https://github.com/gfx-rs/wgpu/pull/2913)
 
 #### DX12
 - `DownlevelCapabilities::default()` now returns the `ANISOTROPIC_FILTERING` flag set to true so DX12 lists `ANISOTROPIC_FILTERING` as true again by @cwfitzgerald in [#2851](https://github.com/gfx-rs/wgpu/pull/2851)

wgpu-core/src/device/mod.rs

@@ -2469,6 +2469,16 @@ impl<A: HalApi> Device<A> {
             ArrayVec::<binding_model::BindEntryMap, { hal::MAX_BIND_GROUPS }>::new();
         let mut shader_binding_sizes = FastHashMap::default();
 
+        let num_attachments = desc.fragment.as_ref().map(|f| f.targets.len()).unwrap_or(0);
+        if num_attachments > hal::MAX_COLOR_ATTACHMENTS {
+            return Err(
+                pipeline::CreateRenderPipelineError::TooManyColorAttachments {
+                    given: num_attachments as u32,
+                    limit: hal::MAX_COLOR_ATTACHMENTS as u32,
+                },
+            );
+        }
+
         let color_targets = desc
             .fragment
             .as_ref()

wgpu-core/src/pipeline.rs

@@ -323,6 +323,8 @@ pub enum CreateRenderPipelineError {
     DepthStencilState(#[from] DepthStencilStateError),
     #[error("invalid sample count {0}")]
     InvalidSampleCount(u32),
+    #[error("the number of color attachments {given} exceeds the limit {limit}")]
+    TooManyColorAttachments { given: u32, limit: u32 },
     #[error("the number of vertex buffers {given} exceeds the limit {limit}")]
     TooManyVertexBuffers { given: u32, limit: u32 },
     #[error("the total number of vertex attributes {given} exceeds the limit {limit}")]