[Merged by Bors] - SystemParam for the name of the system you are currently in

crates/bevy_ecs/src/system/mod.rs

@@ -59,6 +59,7 @@
 //! - [`NonSendMut`] and `Option<NonSendMut>`
 //! - [`&World`](crate::world::World)
 //! - [`RemovedComponents`]
+//! - [`SystemName`]
 //! - [`SystemChangeTick`]
 //! - [`Archetypes`](crate::archetype::Archetypes) (Provides Archetype metadata)
 //! - [`Bundles`](crate::bundle::Bundles) (Provides Bundles metadata)

crates/bevy_ecs/src/system/system_param.rs

@@ -16,6 +16,7 @@ pub use bevy_ecs_macros::SystemParam;
 use bevy_ecs_macros::{all_tuples, impl_param_set};
 use bevy_ptr::UnsafeCellDeref;
 use std::{
+ borrow::Cow,
  fmt::Debug,
  marker::PhantomData,
  ops::{Deref, DerefMut},
@@ -1304,6 +1305,91 @@ impl<'w, 's> SystemParamFetch<'w, 's> for SystemChangeTickState {
  }
 }
 
+/// Name of the system that corresponds to this [`crate::system::SystemState`].
+///
+/// This is not a reliable identifier, it is more so useful for debugging
+/// purposes of finding where a system parameter is being used incorrectly.
+pub struct SystemName<'s> {
+ name: &'s str,
+}
+
+impl<'s> SystemName<'s> {
+ pub fn name(&self) -> &str {
+ self.name
+ }
+}
+
+impl<'s> Deref for SystemName<'s> {
+ type Target = str;
+ fn deref(&self) -> &Self::Target {
+ self.name()
+ }
+}
+
+impl<'s> AsRef<str> for SystemName<'s> {
+ fn as_ref(&self) -> &str {
+ self.name()
+ }
+}
+
+impl<'s> From<SystemName<'s>> for &'s str {
+ fn from(name: SystemName<'s>) -> &'s str {
+ name.name
+ }
+}
+
+impl<'s> std::fmt::Debug for SystemName<'s> {
+ #[inline(always)]
+ fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+ f.debug_tuple("SystemName").field(&self.name()).finish()
+ }
+}
+
+impl<'s> std::fmt::Display for SystemName<'s> {
+ #[inline(always)]
+ fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+ std::fmt::Display::fmt(&self.name(), f)
+ }
+}
+
+impl<'s> SystemParam for SystemName<'s> {
+ type Fetch = SystemNameState;
+}
+
+// SAFETY: Only reads internal system state
+unsafe impl ReadOnlySystemParamFetch for SystemNameState {}
+
+/// The [`SystemParamState`] of [`SystemName`].
+#[doc(hidden)]
+pub struct SystemNameState {
+ name: Cow<'static, str>,
+}
+
+// SAFETY: no component value access
+unsafe impl SystemParamState for SystemNameState {
+ fn init(_world: &mut World, system_meta: &mut SystemMeta) -> Self {
+ Self {
+ name: system_meta.name.clone(),
+ }
+ }
+}
+
+impl<'w, 's> SystemParamFetch<'w, 's> for SystemNameState {
+ type Item = SystemName<'s>;
+
+ #[inline]
+ unsafe fn get_param(
+ state: &'s mut Self,
+ _system_meta: &SystemMeta,
+ _world: &'w World,
+ _change_tick: u32,
+ ) -> Self::Item {
+ SystemName {
+ name: state.name.as_ref(),
+ }
+ }
+}
+
 macro_rules! impl_system_param_tuple {
  ($($param: ident),*) => {
  impl<$($param: SystemParam),*> SystemParam for ($($param,)*) {