Rollup merge of #130136 - GKFX:stabilize-const-pin, r=dtolnay

Partially stabilize const_pin

Tracking issue #76654.

Eight of these methods can be made const-stable. The remainder are blocked on #73255.

5 files changed, 16 insertions, 13 deletions

diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
index 0a4a5160d82..ae9b3739858 100644
--- a/library/alloc/src/lib.rs
+++ b/library/alloc/src/lib.rs
@@ -112,7 +112,6 @@
 #![feature(const_eval_select)]
 #![feature(const_heap)]
 #![feature(const_maybe_uninit_write)]
-#![feature(const_pin)]
 #![feature(const_size_of_val)]
 #![feature(const_vec_string_slice)]
 #![feature(core_intrinsics)]
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 6ed9ccaa694..ad034d3e576 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -129,7 +129,7 @@
 #![feature(const_nonnull_new)]
 #![feature(const_num_midpoint)]
 #![feature(const_option_ext)]
-#![feature(const_pin)]
+#![feature(const_pin_2)]
 #![feature(const_pointer_is_aligned)]
 #![feature(const_ptr_is_null)]
 #![feature(const_ptr_sub_ptr)]
diff --git a/library/core/src/pin.rs b/library/core/src/pin.rs
index fac789dbd99..5d5733d38fc 100644
--- a/library/core/src/pin.rs
+++ b/library/core/src/pin.rs
@@ -1186,7 +1186,7 @@ impl<Ptr: Deref<Target: Unpin>> Pin<Ptr> {
     /// let mut pinned: Pin<&mut u8> = Pin::new(&mut val);
     /// ```
     #[inline(always)]
-    #[rustc_const_unstable(feature = "const_pin", issue = "76654")]
+    #[rustc_const_stable(feature = "const_pin", since = "CURRENT_RUSTC_VERSION")]
     #[stable(feature = "pin", since = "1.33.0")]
     pub const fn new(pointer: Ptr) -> Pin<Ptr> {
         // SAFETY: the value pointed to is `Unpin`, and so has no requirements
@@ -1214,7 +1214,7 @@ impl<Ptr: Deref<Target: Unpin>> Pin<Ptr> {
     /// assert_eq!(*r, 5);
     /// ```
     #[inline(always)]
-    #[rustc_const_unstable(feature = "const_pin", issue = "76654")]
+    #[rustc_const_unstable(feature = "const_pin_2", issue = "76654")]
     #[stable(feature = "pin_into_inner", since = "1.39.0")]
     pub const fn into_inner(pin: Pin<Ptr>) -> Ptr {
         pin.__pointer
@@ -1351,7 +1351,7 @@ impl<Ptr: Deref> Pin<Ptr> {
     /// [`pin` module docs]: self
     #[lang = "new_unchecked"]
     #[inline(always)]
-    #[rustc_const_unstable(feature = "const_pin", issue = "76654")]
+    #[rustc_const_stable(feature = "const_pin", since = "CURRENT_RUSTC_VERSION")]
     #[stable(feature = "pin", since = "1.33.0")]
     pub const unsafe fn new_unchecked(pointer: Ptr) -> Pin<Ptr> {
         Pin { __pointer: pointer }
@@ -1503,7 +1503,7 @@ impl<Ptr: Deref> Pin<Ptr> {
     /// If the underlying data is [`Unpin`], [`Pin::into_inner`] should be used
     /// instead.
     #[inline(always)]
-    #[rustc_const_unstable(feature = "const_pin", issue = "76654")]
+    #[rustc_const_unstable(feature = "const_pin_2", issue = "76654")]
     #[stable(feature = "pin_into_inner", since = "1.39.0")]
     pub const unsafe fn into_inner_unchecked(pin: Pin<Ptr>) -> Ptr {
         pin.__pointer
@@ -1559,7 +1559,7 @@ impl<'a, T: ?Sized> Pin<&'a T> {
     /// ["pinning projections"]: self#projections-and-structural-pinning
     #[inline(always)]
     #[must_use]
-    #[rustc_const_unstable(feature = "const_pin", issue = "76654")]
+    #[rustc_const_stable(feature = "const_pin", since = "CURRENT_RUSTC_VERSION")]
     #[stable(feature = "pin", since = "1.33.0")]
     pub const fn get_ref(self) -> &'a T {
         self.__pointer
@@ -1570,7 +1570,7 @@ impl<'a, T: ?Sized> Pin<&'a mut T> {
     /// Converts this `Pin<&mut T>` into a `Pin<&T>` with the same lifetime.
     #[inline(always)]
     #[must_use = "`self` will be dropped if the result is not used"]
-    #[rustc_const_unstable(feature = "const_pin", issue = "76654")]
+    #[rustc_const_stable(feature = "const_pin", since = "CURRENT_RUSTC_VERSION")]
     #[stable(feature = "pin", since = "1.33.0")]
     pub const fn into_ref(self) -> Pin<&'a T> {
         Pin { __pointer: self.__pointer }
@@ -1588,7 +1588,7 @@ impl<'a, T: ?Sized> Pin<&'a mut T> {
     #[inline(always)]
     #[must_use = "`self` will be dropped if the result is not used"]
     #[stable(feature = "pin", since = "1.33.0")]
-    #[rustc_const_unstable(feature = "const_pin", issue = "76654")]
+    #[rustc_const_stable(feature = "const_pin", since = "CURRENT_RUSTC_VERSION")]
     pub const fn get_mut(self) -> &'a mut T
     where
         T: Unpin,
@@ -1609,7 +1609,7 @@ impl<'a, T: ?Sized> Pin<&'a mut T> {
     #[inline(always)]
     #[must_use = "`self` will be dropped if the result is not used"]
     #[stable(feature = "pin", since = "1.33.0")]
-    #[rustc_const_unstable(feature = "const_pin", issue = "76654")]
+    #[rustc_const_stable(feature = "const_pin", since = "CURRENT_RUSTC_VERSION")]
     pub const unsafe fn get_unchecked_mut(self) -> &'a mut T {
         self.__pointer
     }
@@ -1652,7 +1652,7 @@ impl<T: ?Sized> Pin<&'static T> {
     /// This is safe because `T` is borrowed immutably for the `'static` lifetime, which
     /// never ends.
     #[stable(feature = "pin_static_ref", since = "1.61.0")]
-    #[rustc_const_unstable(feature = "const_pin", issue = "76654")]
+    #[rustc_const_stable(feature = "const_pin", since = "CURRENT_RUSTC_VERSION")]
     pub const fn static_ref(r: &'static T) -> Pin<&'static T> {
         // SAFETY: The 'static borrow guarantees the data will not be
         // moved/invalidated until it gets dropped (which is never).
@@ -1666,7 +1666,7 @@ impl<T: ?Sized> Pin<&'static mut T> {
     /// This is safe because `T` is borrowed for the `'static` lifetime, which
     /// never ends.
     #[stable(feature = "pin_static_ref", since = "1.61.0")]
-    #[rustc_const_unstable(feature = "const_pin", issue = "76654")]
+    #[rustc_const_stable(feature = "const_pin", since = "CURRENT_RUSTC_VERSION")]
     pub const fn static_mut(r: &'static mut T) -> Pin<&'static mut T> {
         // SAFETY: The 'static borrow guarantees the data will not be
         // moved/invalidated until it gets dropped (which is never).
diff --git a/library/core/tests/lib.rs b/library/core/tests/lib.rs
index bfc0b638b7e..443090097c0 100644
--- a/library/core/tests/lib.rs
+++ b/library/core/tests/lib.rs
@@ -21,7 +21,7 @@
 #![feature(const_likely)]
 #![feature(const_nonnull_new)]
 #![feature(const_option_ext)]
-#![feature(const_pin)]
+#![feature(const_pin_2)]
 #![feature(const_pointer_is_aligned)]
 #![feature(const_three_way_compare)]
 #![feature(const_trait_impl)]
diff --git a/library/core/tests/pin.rs b/library/core/tests/pin.rs
index 7a6af46a743..026d2ca8de2 100644
--- a/library/core/tests/pin.rs
+++ b/library/core/tests/pin.rs
@@ -19,6 +19,10 @@ fn pin_const() {
     const REF: &'static usize = PINNED.get_ref();
     assert_eq!(REF, POINTER);
 
+    const INT: u8 = 42;
+    const STATIC_REF: Pin<&'static u8> = Pin::static_ref(&INT);
+    assert_eq!(*STATIC_REF, INT);
+
     // Note: `pin_mut_const` tests that the methods of `Pin<&mut T>` are usable in a const context.
     // A const fn is used because `&mut` is not (yet) usable in constants.
     const fn pin_mut_const() {