Use new let-else syntax where possible (#6463)

# Objective

Let-else syntax is now stable!

## Solution

Use it where possible!

crates/bevy_pbr/src/light.rs

@@ -970,9 +970,7 @@ pub(crate) fn assign_lights_to_clusters(
             continue;
         }
 
-        let screen_size = if let Some(screen_size) = camera.physical_viewport_size() {
-            screen_size
-        } else {
+        let Some(screen_size) = camera.physical_viewport_size() else {
             clusters.clear();
             continue;
         };

crates/bevy_reflect/bevy_reflect_derive/src/container_attributes.rs

@@ -137,11 +137,10 @@ impl ReflectTraits {
                 // Handles `#[reflect( Hash, Default, ... )]`
                 NestedMeta::Meta(Meta::Path(path)) => {
                     // Get the first ident in the path (hopefully the path only contains one and not `std::hash::Hash`)
-                    let ident = if let Some(segment) = path.segments.iter().next() {
-                        &segment.ident
-                    } else {
+                    let Some(segment) = path.segments.iter().next() else {
                         continue;
                     };
+                    let ident = &segment.ident;
                     let ident_name = ident.to_string();
 
                     // Track the span where the trait is implemented for future errors
@@ -172,12 +171,12 @@ impl ReflectTraits {
                 // Handles `#[reflect( Hash(custom_hash_fn) )]`
                 NestedMeta::Meta(Meta::List(list)) => {
                     // Get the first ident in the path (hopefully the path only contains one and not `std::hash::Hash`)
-                    let ident = if let Some(segment) = list.path.segments.iter().next() {
-                        segment.ident.to_string()
-                    } else {
+                    let Some(segment) = list.path.segments.iter().next() else {
                         continue;
                     };
 
+                    let ident = segment.ident.to_string();
+
                     // Track the span where the trait is implemented for future errors
                     let span = ident.span();
 

crates/bevy_reflect/bevy_reflect_derive/src/type_uuid.rs

@@ -24,9 +24,7 @@ pub(crate) fn type_uuid_derive(input: proc_macro::TokenStream) -> proc_macro::To
 
     let mut uuid = None;
     for attribute in ast.attrs.iter().filter_map(|attr| attr.parse_meta().ok()) {
-        let name_value = if let Meta::NameValue(name_value) = attribute {
-            name_value
-        } else {
+        let Meta::NameValue(name_value) = attribute else {
             continue;
         };
 

crates/bevy_reflect/src/enums/helpers.rs

@@ -26,9 +26,7 @@ pub fn enum_hash<TEnum: Enum>(value: &TEnum) -> Option<u64> {
 #[inline]
 pub fn enum_partial_eq<TEnum: Enum>(a: &TEnum, b: &dyn Reflect) -> Option<bool> {
     // Both enums?
-    let b = if let ReflectRef::Enum(e) = b.reflect_ref() {
-        e
-    } else {
+    let ReflectRef::Enum(b) = b.reflect_ref() else {
         return Some(false);
     };
 

crates/bevy_reflect/src/list.rs

@@ -324,9 +324,7 @@ pub fn list_apply<L: List>(a: &mut L, b: &dyn Reflect) {
 /// Returns [`None`] if the comparison couldn't even be performed.
 #[inline]
 pub fn list_partial_eq<L: List>(a: &L, b: &dyn Reflect) -> Option<bool> {
-    let list = if let ReflectRef::List(list) = b.reflect_ref() {
-        list
-    } else {
+    let ReflectRef::List(list) = b.reflect_ref() else {
         return Some(false);
     };
 

crates/bevy_reflect/src/map.rs

@@ -371,9 +371,7 @@ impl<'a> ExactSizeIterator for MapIter<'a> {}
 /// Returns [`None`] if the comparison couldn't even be performed.
 #[inline]
 pub fn map_partial_eq<M: Map>(a: &M, b: &dyn Reflect) -> Option<bool> {
-    let map = if let ReflectRef::Map(map) = b.reflect_ref() {
-        map
-    } else {
+    let ReflectRef::Map(map) = b.reflect_ref() else {
         return Some(false);
     };
 

crates/bevy_reflect/src/struct_trait.rs

@@ -480,9 +480,7 @@ impl Typed for DynamicStruct {
 /// Returns [`None`] if the comparison couldn't even be performed.
 #[inline]
 pub fn struct_partial_eq<S: Struct>(a: &S, b: &dyn Reflect) -> Option<bool> {
-    let struct_value = if let ReflectRef::Struct(struct_value) = b.reflect_ref() {
-        struct_value
-    } else {
+    let ReflectRef::Struct(struct_value) = b.reflect_ref()  else {
         return Some(false);
     };
 

crates/bevy_reflect/src/tuple.rs

@@ -396,9 +396,7 @@ pub fn tuple_apply<T: Tuple>(a: &mut T, b: &dyn Reflect) {
 /// Returns [`None`] if the comparison couldn't even be performed.
 #[inline]
 pub fn tuple_partial_eq<T: Tuple>(a: &T, b: &dyn Reflect) -> Option<bool> {
-    let b = if let ReflectRef::Tuple(tuple) = b.reflect_ref() {
-        tuple
-    } else {
+    let ReflectRef::Tuple(b) = b.reflect_ref() else {
         return Some(false);
     };
 

crates/bevy_reflect/src/tuple_struct.rs

@@ -381,9 +381,7 @@ impl Typed for DynamicTupleStruct {
 /// Returns [`None`] if the comparison couldn't even be performed.
 #[inline]
 pub fn tuple_struct_partial_eq<S: TupleStruct>(a: &S, b: &dyn Reflect) -> Option<bool> {
-    let tuple_struct = if let ReflectRef::TupleStruct(tuple_struct) = b.reflect_ref() {
-        tuple_struct
-    } else {
+    let ReflectRef::TupleStruct(tuple_struct) = b.reflect_ref() else {
         return Some(false);
     };
 

crates/bevy_render/macros/src/as_bind_group.rs

@@ -116,9 +116,7 @@ pub fn derive_as_bind_group(ast: syn::DeriveInput) -> Result<TokenStream> {
     // Read field-level attributes
     for field in fields.iter() {
         for attr in &field.attrs {
-            let attr_ident = if let Some(ident) = attr.path.get_ident() {
-                ident
-            } else {
+            let Some(attr_ident) = attr.path.get_ident() else {
                 continue;
             };
 

crates/bevy_render/src/camera/camera_driver_node.rs

@@ -78,9 +78,7 @@ impl Node for CameraDriverNode {
                 continue;
             }
 
-            let swap_chain_texture = if let Some(swap_chain_texture) = &window.swap_chain_texture {
-                swap_chain_texture
-            } else {
+            let Some(swap_chain_texture) = &window.swap_chain_texture else {
                 continue;
             };
 

crates/bevy_render/src/texture/basis.rs

@@ -20,9 +20,7 @@ pub fn basis_buffer_to_image(
         return Err(TextureError::InvalidData("Invalid header".to_string()));
     }
 
-    let image0_info = if let Some(image_info) = transcoder.image_info(buffer, 0) {
-        image_info
-    } else {
+    let Some(image0_info) = transcoder.image_info(buffer, 0) else {
         return Err(TextureError::InvalidData(
             "Failed to get image info".to_string(),
         ));

crates/bevy_ui/src/render/render_pass.rs

@@ -54,10 +54,9 @@ impl Node for UiPassNode {
     ) -> Result<(), NodeRunError> {
         let input_view_entity = graph.get_input_entity(Self::IN_VIEW)?;
 
-        let (transparent_phase, target, camera_ui) =
-            if let Ok(result) = self.ui_view_query.get_manual(world, input_view_entity) {
-                result
-            } else {
+        let Ok((transparent_phase, target, camera_ui)) =
+                self.ui_view_query.get_manual(world, input_view_entity)
+             else {
                 return Ok(());
             };
         if transparent_phase.items.is_empty() {

crates/bevy_winit/src/lib.rs

@@ -398,9 +398,7 @@ pub fn winit_runner_with(mut app: App) {
                         return;
                     };
 
-                let window = if let Some(window) = windows.get_mut(window_id) {
-                    window
-                } else {
+                let Some(window) = windows.get_mut(window_id) else {
                     // If we're here, this window was previously opened
                     info!("Skipped event for closed window: {:?}", window_id);
                     return;

examples/games/contributors.rs

@@ -248,9 +248,7 @@ fn collision_system(
     windows: Res<Windows>,
     mut query: Query<(&mut Velocity, &mut Transform), With<Contributor>>,
 ) {
-    let window = if let Some(window) = windows.get_primary() {
-        window
-    } else {
+    let Some(window) = windows.get_primary() else {
         return;
     };