Don't fold in Instantiate when there's nothing to fold

compiler-errors · compiler-errors · commit cbd67db267fc · 2025-06-10T21:09:35.000Z
diff --git a/compiler/rustc_type_ir/src/binder.rs b/compiler/rustc_type_ir/src/binder.rs
@@ -622,6 +622,10 @@ impl<I: Interner, T: TypeFoldable<I>> ty::EarlyBinder<I, T> {
     where
         A: SliceLike<Item = I::GenericArg>,
     {
+        // Nothing to fold.
+        if !cfg!(debug_assertions) && args.is_empty() {
+            return self.value;
+        }
         let mut folder = ArgFolder { cx, args: args.as_slice(), binders_passed: 0 };
         self.value.fold_with(&mut folder)
     }

Original file line number	Diff line number	Diff line change
`@@ -622,6 +622,10 @@ impl<I: Interner, T: TypeFoldable<I>> ty::EarlyBinder<I, T> {`
`622`	`622`	`where`
`623`	`623`	`A: SliceLike<Item = I::GenericArg>,`
`624`	`624`	`{`
	`625`	`+ // Nothing to fold.`
	`626`	`+ if !cfg!(debug_assertions) && args.is_empty() {`
	`627`	`+ return self.value;`
	`628`	`+ }`
`625`	`629`	`let mut folder = ArgFolder { cx, args: args.as_slice(), binders_passed: 0 };`
`626`	`630`	`self.value.fold_with(&mut folder)`
`627`	`631`	`}`