From 135c08fd76ee2db637cb0b878ca848642755c972 Mon Sep 17 00:00:00 2001
From: Tobias Koppers <tobias.koppers@googlemail.com>
Date: Mon, 17 Jul 2023 16:44:56 +0200
Subject: [PATCH] add direct cycle detection (#5544)

### Description

very simple detection of dumb mistakes
---
 crates/turbo-tasks-memory/src/memory_backend.rs | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/crates/turbo-tasks-memory/src/memory_backend.rs b/crates/turbo-tasks-memory/src/memory_backend.rs
index 7c9bb1d81e5bc..a7654e37b00f7 100644
--- a/crates/turbo-tasks-memory/src/memory_backend.rs
+++ b/crates/turbo-tasks-memory/src/memory_backend.rs
@@ -443,11 +443,17 @@ impl Backend for MemoryBackend {
 
     fn task_execution_result(
         &self,
-        task: TaskId,
+        task_id: TaskId,
         result: Result<Result<RawVc>, Option<Cow<'static, str>>>,
         turbo_tasks: &dyn TurboTasksBackendApi<MemoryBackend>,
     ) {
-        self.with_task(task, |task| {
+        self.with_task(task_id, |task| {
+            #[cfg(debug_assertions)]
+            if let Ok(Ok(RawVc::TaskOutput(result))) = result.as_ref() {
+                if *result == task_id {
+                    panic!("Task {} returned itself as output", task.get_description());
+                }
+            }
             task.execution_result(result, self, turbo_tasks);
         })
     }