From 6a63940367de6e3e43072e51b2e5d5d62767961d Mon Sep 17 00:00:00 2001
From: Edgar Geier <egeier@rhrk.uni-kl.de>
Date: Thu, 16 Feb 2023 17:09:46 +0000
Subject: [PATCH] Allow adding systems to multiple sets that share the same
 base set (#7709)

# Objective

Fixes #7702.

## Solution

- Added an test that ensures that no error is returned if a system or set is inside two different sets that share the same base set.
- Added an check to only return an error if the two base sets are not equal.
---
 crates/bevy_ecs/src/schedule/mod.rs      | 22 ++++++++++++++++
 crates/bevy_ecs/src/schedule/schedule.rs | 32 ++++++++++++++----------
 2 files changed, 41 insertions(+), 13 deletions(-)

diff --git a/crates/bevy_ecs/src/schedule/mod.rs b/crates/bevy_ecs/src/schedule/mod.rs
index 5be608768fbcc..91d24615e116f 100644
--- a/crates/bevy_ecs/src/schedule/mod.rs
+++ b/crates/bevy_ecs/src/schedule/mod.rs
@@ -797,6 +797,28 @@ mod tests {
             ));
         }
 
+        #[test]
+        fn allow_same_base_sets() {
+            let mut world = World::new();
+
+            let mut schedule = Schedule::new();
+            schedule
+                .configure_set(Normal::X.in_base_set(Base::A))
+                .configure_set(Normal::Y.in_base_set(Base::A))
+                .add_system(named_system.in_set(Normal::X).in_set(Normal::Y));
+
+            let result = schedule.initialize(&mut world);
+            assert!(matches!(result, Ok(())));
+
+            let mut schedule = Schedule::new();
+            schedule
+                .configure_set(Normal::X.in_base_set(Base::A))
+                .configure_set(Normal::Y.in_base_set(Base::A).in_set(Normal::X));
+
+            let result = schedule.initialize(&mut world);
+            assert!(matches!(result, Ok(())));
+        }
+
         #[test]
         fn default_base_set_ordering() {
             let mut world = World::default();
diff --git a/crates/bevy_ecs/src/schedule/schedule.rs b/crates/bevy_ecs/src/schedule/schedule.rs
index 49e0b1afe2e39..581f80f0086ad 100644
--- a/crates/bevy_ecs/src/schedule/schedule.rs
+++ b/crates/bevy_ecs/src/schedule/schedule.rs
@@ -840,20 +840,26 @@ impl ScheduleGraph {
                         neighbor,
                     )? {
                         if let Some(first_set) = base_set {
-                            return Err(match node_id {
-                                NodeId::System(index) => {
-                                    ScheduleBuildError::SystemInMultipleBaseSets {
-                                        system: systems[index].name(),
-                                        first_set: system_sets[first_set.index()].name(),
-                                        second_set: system_sets[calculated_base_set.index()].name(),
+                            if first_set != calculated_base_set {
+                                return Err(match node_id {
+                                    NodeId::System(index) => {
+                                        ScheduleBuildError::SystemInMultipleBaseSets {
+                                            system: systems[index].name(),
+                                            first_set: system_sets[first_set.index()].name(),
+                                            second_set: system_sets[calculated_base_set.index()]
+                                                .name(),
+                                        }
                                     }
-                                }
-                                NodeId::Set(index) => ScheduleBuildError::SetInMultipleBaseSets {
-                                    set: system_sets[index].name(),
-                                    first_set: system_sets[first_set.index()].name(),
-                                    second_set: system_sets[calculated_base_set.index()].name(),
-                                },
-                            });
+                                    NodeId::Set(index) => {
+                                        ScheduleBuildError::SetInMultipleBaseSets {
+                                            set: system_sets[index].name(),
+                                            first_set: system_sets[first_set.index()].name(),
+                                            second_set: system_sets[calculated_base_set.index()]
+                                                .name(),
+                                        }
+                                    }
+                                });
+                            }
                         }
                         base_set = Some(calculated_base_set);
                     }