From 922b1bd8fffb96c635f1e302190a548dc33e6f16 Mon Sep 17 00:00:00 2001
From: JoJoJet <21144246+JoJoJet@users.noreply.github.com>
Date: Sat, 24 Dec 2022 01:48:38 -0500
Subject: [PATCH 1/5] add a const constructor to `Access`

---
 crates/bevy_ecs/src/query/access.rs | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/crates/bevy_ecs/src/query/access.rs b/crates/bevy_ecs/src/query/access.rs
index a28e6df23ef83..e319349e48c03 100644
--- a/crates/bevy_ecs/src/query/access.rs
+++ b/crates/bevy_ecs/src/query/access.rs
@@ -71,16 +71,20 @@ impl<T: SparseSetIndex + fmt::Debug> fmt::Debug for Access<T> {
 }
 impl<T: SparseSetIndex> Default for Access<T> {
     fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl<T: SparseSetIndex> Access<T> {
+    pub const fn new() -> Self {
         Self {
             reads_all: false,
-            reads_and_writes: Default::default(),
-            writes: Default::default(),
+            reads_and_writes: FixedBitSet::new(),
+            writes: FixedBitSet::new(),
             marker: PhantomData,
         }
     }
-}
 
-impl<T: SparseSetIndex> Access<T> {
     /// Increases the set capacity to the specified amount.
     ///
     /// Does nothing if `capacity` is less than or equal to the current value.

From 7083845f8e02e93d73987a13fa2ef39e3df2eb72 Mon Sep 17 00:00:00 2001
From: JoJoJet <21144246+JoJoJet@users.noreply.github.com>
Date: Sat, 24 Dec 2022 01:48:54 -0500
Subject: [PATCH 2/5] add a const constructor to `PipeSystem`

---
 crates/bevy_ecs/src/system/system_piping.rs | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/crates/bevy_ecs/src/system/system_piping.rs b/crates/bevy_ecs/src/system/system_piping.rs
index d28158b697836..1541ecf0abcde 100644
--- a/crates/bevy_ecs/src/system/system_piping.rs
+++ b/crates/bevy_ecs/src/system/system_piping.rs
@@ -54,6 +54,18 @@ pub struct PipeSystem<SystemA, SystemB> {
     archetype_component_access: Access<ArchetypeComponentId>,
 }
 
+impl<SystemA, SystemB> PipeSystem<SystemA, SystemB> {
+    pub const fn new(system_a: SystemA, system_b: SystemB, name: Cow<'static, str>) -> Self {
+        Self {
+            system_a,
+            system_b,
+            name,
+            component_access: Access::new(),
+            archetype_component_access: Access::new(),
+        }
+    }
+}
+
 impl<SystemA: System, SystemB: System<In = SystemA::Out>> System for PipeSystem<SystemA, SystemB> {
     type In = SystemA::In;
     type Out = SystemB::Out;

From e76333343c0308f51acf8c150f578f7fce8ebabe Mon Sep 17 00:00:00 2001
From: JoJoJet <21144246+JoJoJet@users.noreply.github.com>
Date: Sat, 24 Dec 2022 01:51:32 -0500
Subject: [PATCH 3/5] use `PipeSystem::new` internally

---
 crates/bevy_ecs/src/system/system_piping.rs | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/crates/bevy_ecs/src/system/system_piping.rs b/crates/bevy_ecs/src/system/system_piping.rs
index 1541ecf0abcde..b18e82cc7f8c6 100644
--- a/crates/bevy_ecs/src/system/system_piping.rs
+++ b/crates/bevy_ecs/src/system/system_piping.rs
@@ -166,13 +166,8 @@ where
     fn pipe(self, system: SystemB) -> PipeSystem<SystemA::System, SystemB::System> {
         let system_a = IntoSystem::into_system(self);
         let system_b = IntoSystem::into_system(system);
-        PipeSystem {
-            name: Cow::Owned(format!("Pipe({}, {})", system_a.name(), system_b.name())),
-            system_a,
-            system_b,
-            archetype_component_access: Default::default(),
-            component_access: Default::default(),
-        }
+        let name = format!("Pipe({}, {})", system_a.name(), system_b.name());
+        PipeSystem::new(system_a, system_b, Cow::Owned(name))
     }
 }
 

From acc576b38a8cecbe80c161e212453619d8ab8dba Mon Sep 17 00:00:00 2001
From: JoJoJet <21144246+JoJoJet@users.noreply.github.com>
Date: Sat, 24 Dec 2022 01:53:38 -0500
Subject: [PATCH 4/5] document `Access::new`

---
 crates/bevy_ecs/src/query/access.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/crates/bevy_ecs/src/query/access.rs b/crates/bevy_ecs/src/query/access.rs
index e319349e48c03..ea18adf841073 100644
--- a/crates/bevy_ecs/src/query/access.rs
+++ b/crates/bevy_ecs/src/query/access.rs
@@ -76,6 +76,7 @@ impl<T: SparseSetIndex> Default for Access<T> {
 }
 
 impl<T: SparseSetIndex> Access<T> {
+    /// Creates an empty [`Access`] collection.
     pub const fn new() -> Self {
         Self {
             reads_all: false,

From ebba24478166548367f426c4f257ee0c35e203d6 Mon Sep 17 00:00:00 2001
From: JoJoJet <21144246+JoJoJet@users.noreply.github.com>
Date: Sat, 24 Dec 2022 01:55:16 -0500
Subject: [PATCH 5/5] document `PipeSystem::new`

---
 crates/bevy_ecs/src/system/system_piping.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/crates/bevy_ecs/src/system/system_piping.rs b/crates/bevy_ecs/src/system/system_piping.rs
index b18e82cc7f8c6..dd343461b9e5f 100644
--- a/crates/bevy_ecs/src/system/system_piping.rs
+++ b/crates/bevy_ecs/src/system/system_piping.rs
@@ -55,6 +55,9 @@ pub struct PipeSystem<SystemA, SystemB> {
 }
 
 impl<SystemA, SystemB> PipeSystem<SystemA, SystemB> {
+    /// Manual constructor for creating a [`PipeSystem`].
+    /// This should only be used when [`IntoPipeSystem::pipe`] cannot be used,
+    /// such as in `const` contexts.
     pub const fn new(system_a: SystemA, system_b: SystemB, name: Cow<'static, str>) -> Self {
         Self {
             system_a,