Add `Future` and `IntoFuture` to the 2024 prelude

Implements RFC 3509.

library/core/src/prelude/mod.rs

@@ -49,9 +49,13 @@ pub mod rust_2021 {
 /// The 2024 edition of the core prelude.
 ///
 /// See the [module-level documentation](self) for more.
-#[unstable(feature = "prelude_2024", issue = "none")]
+#[unstable(feature = "prelude_2024", issue = "121042")]
 pub mod rust_2024 {
-    #[unstable(feature = "prelude_2024", issue = "none")]
+    #[unstable(feature = "prelude_2024", issue = "121042")]
     #[doc(no_inline)]
     pub use super::rust_2021::*;
+
+    #[unstable(feature = "prelude_2024", issue = "121042")]
+    #[doc(no_inline)]
+    pub use crate::future::{Future, IntoFuture};
 }

library/std/src/prelude/mod.rs

@@ -132,13 +132,13 @@ pub mod rust_2021 {
 /// The 2024 version of the prelude of The Rust Standard Library.
 ///
 /// See the [module-level documentation](self) for more.
-#[unstable(feature = "prelude_2024", issue = "none")]
+#[unstable(feature = "prelude_2024", issue = "121042")]
 pub mod rust_2024 {
-    #[unstable(feature = "prelude_2024", issue = "none")]
+    #[unstable(feature = "prelude_2024", issue = "121042")]
     #[doc(no_inline)]
     pub use super::v1::*;
 
-    #[unstable(feature = "prelude_2024", issue = "none")]
+    #[unstable(feature = "prelude_2024", issue = "121042")]
     #[doc(no_inline)]
     pub use core::prelude::rust_2024::*;
 }

src/tools/tidy/src/ui_tests.rs

@@ -16,7 +16,7 @@ const ENTRY_LIMIT: usize = 900;
 // FIXME: The following limits should be reduced eventually.
 
 const ISSUES_ENTRY_LIMIT: usize = 1781;
-const ROOT_ENTRY_LIMIT: usize = 871;
+const ROOT_ENTRY_LIMIT: usize = 872;
 
 const EXPECTED_TEST_FILE_EXTENSIONS: &[&str] = &[
     "rs",     // test source files

tests/ui/async-await/for-await-passthrough.rs

@@ -4,8 +4,6 @@
 #![feature(async_iterator, async_iter_from_iter, const_waker, async_for_loop, noop_waker,
            gen_blocks)]
 
-use std::future::Future;
-
 async gen fn async_iter() -> i32 {
     let iter = core::async_iter::from_iter(0..3);
     for await i in iter {

tests/ui/coroutine/async_gen_fn_iter.rs

@@ -46,7 +46,6 @@ async fn async_main() {
 use std::pin::{Pin, pin};
 use std::task::*;
 use std::async_iter::AsyncIterator;
-use std::future::Future;
 
 trait AsyncIterExt {
     fn next(&mut self) -> Next<'_, Self>;

tests/ui/rust-2024/prelude2024.rs

@@ -0,0 +1,9 @@
+//@ check-pass
+//@ compile-flags: -Zunstable-options
+//@ edition:2024
+
+fn main() {
+    fut(async {}.into_future(), async {});
+}
+
+fn fut(_: impl Future, _: impl IntoFuture) {}