Emit more info on duplicate components in archetype creation

crates/bevy_ecs/hecs/macros/src/lib.rs

@@ -248,7 +248,7 @@ fn struct_fields(fields: &syn::Fields) -> (Vec<&syn::Type>, Vec<syn::Member>) {
     }
 }
 
-fn member_as_idents<'a>(members: &'a [syn::Member]) -> Vec<Cow<'a, syn::Ident>> {
+fn member_as_idents(members: &[syn::Member]) -> Vec<Cow<'_, syn::Ident>> {
     members
         .iter()
         .map(|member| match member {

crates/bevy_ecs/hecs/src/archetype.rs

@@ -51,17 +51,32 @@ pub struct Archetype {
 }
 
 impl Archetype {
+    fn assert_type_info(types: &[TypeInfo]) {
+        types.windows(2).for_each(|x| match x[0].cmp(&x[1]) {
+            core::cmp::Ordering::Less => (),
+            #[cfg(debug_assertions)]
+            core::cmp::Ordering::Equal => panic!(
+                "attempted to allocate entity with duplicate {} components; \
+                 each type must occur at most once!",
+                x[0].type_name
+            ),
+            #[cfg(not(debug_assertions))]
+            core::cmp::Ordering::Equal => panic!(
+                "attempted to allocate entity with duplicate components; \
+                 each type must occur at most once!"
+            ),
+            core::cmp::Ordering::Greater => panic!("type info is unsorted"),
+        });
+    }
+
     #[allow(missing_docs)]
     pub fn new(types: Vec<TypeInfo>) -> Self {
         Self::with_grow(types, 64)
     }
 
     #[allow(missing_docs)]
     pub fn with_grow(types: Vec<TypeInfo>, grow_size: usize) -> Self {
-        debug_assert!(
-            types.windows(2).all(|x| x[0] < x[1]),
-            "type info unsorted or contains duplicates"
-        );
+        Self::assert_type_info(&types);
         let mut state = HashMap::with_capacity_and_hasher(types.len(), Default::default());
         for ty in &types {
             state.insert(ty.id, TypeState::new());
@@ -484,6 +499,8 @@ pub struct TypeInfo {
     id: TypeId,
     layout: Layout,
     drop: unsafe fn(*mut u8),
+    #[cfg(debug_assertions)]
+    type_name: &'static str,
 }
 
 impl TypeInfo {
@@ -497,6 +514,8 @@ impl TypeInfo {
             id: TypeId::of::<T>(),
             layout: Layout::new::<T>(),
             drop: drop_ptr::<T>,
+            #[cfg(debug_assertions)]
+            type_name: core::any::type_name::<T>(),
         }
     }
 

crates/bevy_ecs/hecs/tests/tests.rs

@@ -183,7 +183,18 @@ fn derived_bundle() {
 
 #[test]
 #[cfg(feature = "macros")]
-#[should_panic(expected = "each type must occur at most once")]
+#[cfg_attr(
+    debug_assertions,
+    should_panic(
+        expected = "attempted to allocate entity with duplicate i32 components; each type must occur at most once!"
+    )
+)]
+#[cfg_attr(
+    not(debug_assertions),
+    should_panic(
+        expected = "attempted to allocate entity with duplicate components; each type must occur at most once!"
+    )
+)]
 fn bad_bundle_derive() {
     #[derive(Bundle)]
     struct Foo {
@@ -361,3 +372,21 @@ fn added_tracking() {
     assert!(world.query_one_mut::<&i32>(a).is_ok());
     assert!(world.query_one_mut::<Added<i32>>(a).is_err());
 }
+
+#[test]
+#[cfg_attr(
+    debug_assertions,
+    should_panic(
+        expected = "attempted to allocate entity with duplicate f32 components; each type must occur at most once!"
+    )
+)]
+#[cfg_attr(
+    not(debug_assertions),
+    should_panic(
+        expected = "attempted to allocate entity with duplicate components; each type must occur at most once!"
+    )
+)]
+fn duplicate_components_panic() {
+    let mut world = World::new();
+    world.reserve::<(f32, i64, f32)>(1);
+}