Slim down GenericArgs by one usize

crates/hir-def/src/item_tree/lower.rs

@@ -659,15 +659,16 @@ fn desugar_future_path(orig: TypeRef) -> Path {
     let path = path![core::future::Future];
     let mut generic_args: Vec<_> =
         std::iter::repeat(None).take(path.segments().len() - 1).collect();
-    let mut last = GenericArgs::empty();
     let binding = AssociatedTypeBinding {
         name: name![Output],
         args: None,
         type_ref: Some(orig),
         bounds: Box::default(),
     };
-    last.bindings.push(binding);
+    generic_args.push(Some(Interned::new(GenericArgs {
-    generic_args.push(Some(Interned::new(last)));
+        bindings: Box::new([binding]),
+        ..GenericArgs::empty()
+    })));
 
     Path::from_known_path(path, generic_args)
 }

crates/hir-def/src/path.rs

@@ -57,7 +57,7 @@ pub struct GenericArgs {
     /// is left out.
     pub has_self_type: bool,
     /// Associated type bindings like in `Iterator<Item = T>`.
-    pub bindings: Vec<AssociatedTypeBinding>,
+    pub bindings: Box<[AssociatedTypeBinding]>,
     /// Whether these generic args were desugared from `Trait(Arg) -> Output`
     /// parenthesis notation typically used for the `Fn` traits.
     pub desugared_from_fn: bool,
@@ -214,7 +214,7 @@ impl GenericArgs {
         GenericArgs {
             args: Vec::new(),
             has_self_type: false,
-            bindings: Vec::new(),
+            bindings: Box::default(),
             desugared_from_fn: false,
         }
     }

crates/hir-def/src/path/lower.rs

@@ -208,7 +208,12 @@ pub(super) fn lower_generic_args(
     if args.is_empty() && bindings.is_empty() {
         return None;
     }
-    Some(GenericArgs { args, has_self_type: false, bindings, desugared_from_fn: false })
+    Some(GenericArgs {
+        args,
+        has_self_type: false,
+        bindings: bindings.into_boxed_slice(),
+        desugared_from_fn: false,
+    })
 }
 
 /// Collect `GenericArgs` from the parts of a fn-like path, i.e. `Fn(X, Y)
@@ -219,7 +224,6 @@ fn lower_generic_args_from_fn_path(
     ret_type: Option<ast::RetType>,
 ) -> Option<GenericArgs> {
     let mut args = Vec::new();
-    let mut bindings = Vec::new();
     let params = params?;
     let mut param_types = Vec::new();
     for param in params.params() {
@@ -228,23 +232,23 @@ fn lower_generic_args_from_fn_path(
     }
     let arg = GenericArg::Type(TypeRef::Tuple(param_types));
     args.push(arg);
-    if let Some(ret_type) = ret_type {
+    let bindings = if let Some(ret_type) = ret_type {
         let type_ref = TypeRef::from_ast_opt(ctx, ret_type.ty());
-        bindings.push(AssociatedTypeBinding {
+        Box::new([AssociatedTypeBinding {
             name: name![Output],
             args: None,
             type_ref: Some(type_ref),
             bounds: Box::default(),
-        });
+        }])
     } else {
         // -> ()
         let type_ref = TypeRef::Tuple(Vec::new());
-        bindings.push(AssociatedTypeBinding {
+        Box::new([AssociatedTypeBinding {
             name: name![Output],
             args: None,
             type_ref: Some(type_ref),
             bounds: Box::default(),
-        });
+        }])
-    }
+    };
     Some(GenericArgs { args, has_self_type: false, bindings, desugared_from_fn: true })
 }

crates/hir-def/src/pretty.rs

@@ -71,7 +71,7 @@ pub(crate) fn print_generic_args(generics: &GenericArgs, buf: &mut dyn Write) ->
         first = false;
         print_generic_arg(arg, buf)?;
     }
-    for binding in &generics.bindings {
+    for binding in generics.bindings.iter() {
         if !first {
             write!(buf, ", ")?;
         }

crates/hir-def/src/type_ref.rs

@@ -301,7 +301,7 @@ impl TypeRef {
                             | crate::path::GenericArg::Lifetime(_) => {}
                         }
                     }
-                    for binding in &args_and_bindings.bindings {
+                    for binding in args_and_bindings.bindings.iter() {
                         if let Some(type_ref) = &binding.type_ref {
                             go(type_ref, f);
                         }

crates/hir-ty/src/display.rs

@@ -1431,7 +1431,7 @@ impl HirDisplay for Path {
                     }
                     arg.hir_fmt(f)?;
                 }
-                for binding in &generic_args.bindings {
+                for binding in generic_args.bindings.iter() {
                     if first {
                         first = false;
                     } else {

crates/hir-ty/src/lower.rs

@@ -1025,7 +1025,7 @@ impl<'a> TyLoweringContext<'a> {
         last_segment
             .into_iter()
             .filter_map(|segment| segment.args_and_bindings)
-            .flat_map(|args_and_bindings| &args_and_bindings.bindings)
+            .flat_map(|args_and_bindings| args_and_bindings.bindings.iter())
             .flat_map(move |binding| {
                 let found = associated_type_by_name_including_super_traits(
                     self.db,