Rollup merge of #103945 - H4x5:remove-iter-empty-hack, r=compiler-errors

Remove `iter::Empty` hack

`iter::Empty` uses a newtype to work around `#![feature(const_fn_fn_ptr_basics)]`, which has been stable since 1.61.0.
This commit is contained in:
fee1-dead 2022-12-28 15:51:38 +08:00 committed by GitHub
commit d1193ad1e6
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23

View File

@ -22,17 +22,12 @@ pub const fn empty<T>() -> Empty<T> {
Empty(marker::PhantomData)
}
// Newtype for use in `PhantomData` to avoid
// > error: const-stable function cannot use `#[feature(const_fn_fn_ptr_basics)]`
// in `const fn empty<T>()` above.
struct FnReturning<T>(fn() -> T);
/// An iterator that yields nothing.
///
/// This `struct` is created by the [`empty()`] function. See its documentation for more.
#[must_use = "iterators are lazy and do nothing unless consumed"]
#[stable(feature = "iter_empty", since = "1.2.0")]
pub struct Empty<T>(marker::PhantomData<FnReturning<T>>);
pub struct Empty<T>(marker::PhantomData<fn() -> T>);
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<T> fmt::Debug for Empty<T> {