where
F: FnOnce() -> R,
{
- let old_bounds = mem::replace(&mut *cx.impl_trait_bounds.borrow_mut(), Default::default());
+ let old_bounds = mem::take(&mut *cx.impl_trait_bounds.borrow_mut());
let r = f();
assert!(cx.impl_trait_bounds.borrow().is_empty());
*cx.impl_trait_bounds.borrow_mut() = old_bounds;