From 8eb85ea72031e0b07229d214499dbaa01c537ee3 Mon Sep 17 00:00:00 2001
From: Brian Reavis <brian@thirdroute.com>
Date: Wed, 9 Apr 2025 09:55:19 -0700
Subject: [PATCH] Fix `get_render_pipeline_state` /
 `get_compute_pipeline_state` panic (#18752)

This fixes a panic that occurs if one calls
`PipelineCache::get_render_pipeline_state(id)` or
`PipelineCache::get_compute_pipeline_state(id)` with a queued pipeline
id that has not yet been processed by `PipelineCache::process_queue()`.

```
thread 'Compute Task Pool (0)' panicked at [...]/bevy/crates/bevy_render/src/render_resource/pipeline_cache.rs:611:24:
index out of bounds: the len is 0 but the index is 20
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
```
---
 .../src/render_resource/pipeline_cache.rs     | 20 +++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/crates/bevy_render/src/render_resource/pipeline_cache.rs b/crates/bevy_render/src/render_resource/pipeline_cache.rs
index 70086cb6b2..613737f3de 100644
--- a/crates/bevy_render/src/render_resource/pipeline_cache.rs
+++ b/crates/bevy_render/src/render_resource/pipeline_cache.rs
@@ -608,7 +608,10 @@ impl PipelineCache {
     /// See [`PipelineCache::queue_render_pipeline()`].
     #[inline]
     pub fn get_render_pipeline_state(&self, id: CachedRenderPipelineId) -> &CachedPipelineState {
-        &self.pipelines[id.0].state
+        // If the pipeline id isn't in `pipelines`, it's queued in `new_pipelines`
+        self.pipelines
+            .get(id.0)
+            .map_or(&CachedPipelineState::Queued, |pipeline| &pipeline.state)
     }
 
     /// Get the state of a cached compute pipeline.
@@ -616,12 +619,18 @@ impl PipelineCache {
     /// See [`PipelineCache::queue_compute_pipeline()`].
     #[inline]
     pub fn get_compute_pipeline_state(&self, id: CachedComputePipelineId) -> &CachedPipelineState {
-        &self.pipelines[id.0].state
+        // If the pipeline id isn't in `pipelines`, it's queued in `new_pipelines`
+        self.pipelines
+            .get(id.0)
+            .map_or(&CachedPipelineState::Queued, |pipeline| &pipeline.state)
     }
 
     /// Get the render pipeline descriptor a cached render pipeline was inserted from.
     ///
     /// See [`PipelineCache::queue_render_pipeline()`].
+    ///
+    /// **Note**: Be careful calling this method. It will panic if called with a pipeline that
+    /// has been queued but has not yet been processed by [`PipelineCache::process_queue()`].
     #[inline]
     pub fn get_render_pipeline_descriptor(
         &self,
@@ -636,6 +645,9 @@ impl PipelineCache {
     /// Get the compute pipeline descriptor a cached render pipeline was inserted from.
     ///
     /// See [`PipelineCache::queue_compute_pipeline()`].
+    ///
+    /// **Note**: Be careful calling this method. It will panic if called with a pipeline that
+    /// has been queued but has not yet been processed by [`PipelineCache::process_queue()`].
     #[inline]
     pub fn get_compute_pipeline_descriptor(
         &self,
@@ -657,7 +669,7 @@ impl PipelineCache {
     #[inline]
     pub fn get_render_pipeline(&self, id: CachedRenderPipelineId) -> Option<&RenderPipeline> {
         if let CachedPipelineState::Ok(Pipeline::RenderPipeline(pipeline)) =
-            &self.pipelines[id.0].state
+            &self.pipelines.get(id.0)?.state
         {
             Some(pipeline)
         } else {
@@ -691,7 +703,7 @@ impl PipelineCache {
     #[inline]
     pub fn get_compute_pipeline(&self, id: CachedComputePipelineId) -> Option<&ComputePipeline> {
         if let CachedPipelineState::Ok(Pipeline::ComputePipeline(pipeline)) =
-            &self.pipelines[id.0].state
+            &self.pipelines.get(id.0)?.state
         {
             Some(pipeline)
         } else {