From ac29bdfc86b1f9326f0ca03b2e1561635e0e2062 Mon Sep 17 00:00:00 2001
From: Brian Reavis <brian@thirdroute.com>
Date: Thu, 15 Aug 2024 11:41:01 -0700
Subject: [PATCH] Fix pass_span drop panic obscuring transparent 2d render
 errors (#14758)

# Objective

When an item in the transparent 2d phase fails to render, bevy crashes
with _"PassSpanScope::end was never called"_ instead of outputting the
actual error to the console. This PR fixes this so that phase errors are
output to the console. It also makes bevy not crash.

```
thread '<unnamed>' panicked at /Users/brianreavis/Repositories/project/bevy/crates/bevy_render/src/diagnostic/mod.rs:157:9:
PassSpanScope::end was never called
stack backtrace:
   0: rust_begin_unwind
             at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/panicking.rs:652:5
   1: core::panicking::panic_fmt
             at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/panicking.rs:72:14
   2: <bevy_render::diagnostic::PassSpanGuard<R,P> as core::ops::drop::Drop>::drop
             at /Users/brianreavis/Repositories/project/bevy/crates/bevy_render/src/diagnostic/mod.rs:157:9
   3: core::ptr::drop_in_place<bevy_render::diagnostic::PassSpanGuard<core::option::Option<alloc::sync::Arc<bevy_render::diagnostic::internal::DiagnosticsRecorder>>,bevy_render::render_phase::draw_state::TrackedRenderPass>>
             at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/ptr/mod.rs:514:1
   4: <bevy_core_pipeline::core_2d::main_transparent_pass_2d_node::MainTransparentPass2dNode as bevy_render::render_graph::node::ViewNode>::run
             at /Users/brianreavis/Repositories/project/bevy/crates/bevy_core_pipeline/src/core_2d/main_transparent_pass_2d_node.rs:75:9
   5: <bevy_render::render_graph::node::ViewNodeRunner<T> as bevy_render::render_graph::node::Node>::run
             at /Users/brianreavis/Repositories/project/bevy/crates/bevy_render/src/render_graph/node.rs:406:9
   6: bevy_render::renderer::graph_runner::RenderGraphRunner::run_graph
             at /Users/brianreavis/Repositories/project/bevy/crates/bevy_render/src/renderer/graph_runner.rs:226:21
   7: bevy_render::renderer::graph_runner::RenderGraphRunner::run_graph
             at /Users/brianreavis/Repositories/project/bevy/crates/bevy_render/src/renderer/graph_runner.rs:233:21
   8: bevy_render::renderer::graph_runner::RenderGraphRunner::run
             at /Users/brianreavis/Repositories/project/bevy/crates/bevy_render/src/renderer/graph_runner.rs:81:9
   9: bevy_render::renderer::render_system
             at /Users/brianreavis/Repositories/project/bevy/crates/bevy_render/src/renderer/mod.rs:40:15
  10: core::ops::function::FnMut::call_mut
             at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/ops/function.rs:166:5
  11: core::ops::function::impls::<impl core::ops::function::FnMut<A> for &mut F>::call_mut
             at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/ops/function.rs:294:13
  12: <Func as bevy_ecs::system::exclusive_function_system::ExclusiveSystemParamFunction<fn(F0) .> Out>>::run::call_inner
             at /Users/brianreavis/Repositories/project/bevy/crates/bevy_ecs/src/system/exclusive_function_system.rs:229:21
  13: <Func as bevy_ecs::system::exclusive_function_system::ExclusiveSystemParamFunction<fn(F0) .> Out>>::run
             at /Users/brianreavis/Repositories/project/bevy/crates/bevy_ecs/src/system/exclusive_function_system.rs:232:17
  14: <bevy_ecs::system::exclusive_function_system::ExclusiveFunctionSystem<Marker,F> as bevy_ecs::system::system::System>::run::{{closure}}
             at /Users/brianreavis/Repositories/project/bevy/crates/bevy_ecs/src/system/exclusive_function_system.rs:124:23
  15: bevy_ecs::world::World::last_change_tick_scope
             at /Users/brianreavis/Repositories/project/bevy/crates/bevy_ecs/src/world/mod.rs:2383:9
  16: <bevy_ecs::system::exclusive_function_system::ExclusiveFunctionSystem<Marker,F> as bevy_ecs::system::system::System>::run
             at /Users/brianreavis/Repositories/project/bevy/crates/bevy_ecs/src/system/exclusive_function_system.rs:116:9
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
```

## Solution

Matched the behavior of the other render phases ([like
here](https://github.com/bevyengine/bevy/blob/9ca5540b759c9e2571147c26b484029d93976be8/crates/bevy_core_pipeline/src/core_3d/main_opaque_pass_3d_node.rs#L98-L101))
---
 .../src/core_2d/main_transparent_pass_2d_node.rs          | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/crates/bevy_core_pipeline/src/core_2d/main_transparent_pass_2d_node.rs b/crates/bevy_core_pipeline/src/core_2d/main_transparent_pass_2d_node.rs
index 2c82ccc800dd7..e365be954775b 100644
--- a/crates/bevy_core_pipeline/src/core_2d/main_transparent_pass_2d_node.rs
+++ b/crates/bevy_core_pipeline/src/core_2d/main_transparent_pass_2d_node.rs
@@ -9,6 +9,7 @@ use bevy_render::{
     renderer::RenderContext,
     view::{ViewDepthTexture, ViewTarget},
 };
+use bevy_utils::tracing::error;
 #[cfg(feature = "trace")]
 use bevy_utils::tracing::info_span;
 
@@ -68,7 +69,12 @@ impl ViewNode for MainTransparentPass2dNode {
             }
 
             if !transparent_phase.items.is_empty() {
-                transparent_phase.render(&mut render_pass, world, view_entity)?;
+                #[cfg(feature = "trace")]
+                let _transparent_main_pass_2d_span =
+                    info_span!("transparent_main_pass_2d").entered();
+                if let Err(err) = transparent_phase.render(&mut render_pass, world, view_entity) {
+                    error!("Error encountered while rendering the transparent 2D phase {err:?}");
+                }
             }
 
             pass_span.end(&mut render_pass);