Rollup merge of rust-lang#145756 - okaneco:stabilize_char_boundary, r=scottmcm

str: Stabilize `round_char_boundary` feature

Closes rust-lang#93743
FCP completed rust-lang#93743 (comment)

Author: tgross35

alloctests/tests/lib.rs

@@ -24,7 +24,6 @@
 #![feature(inplace_iteration)]
 #![feature(iter_advance_by)]
 #![feature(iter_next_chunk)]
-#![feature(round_char_boundary)]
 #![feature(slice_partition_dedup)]
 #![feature(string_from_utf8_lossy_owned)]
 #![feature(string_remove_matches)]

core/src/str/mod.rs

@@ -396,7 +396,6 @@ impl str {
     /// # Examples
     ///
     /// ```
-    /// #![feature(round_char_boundary)]
     /// let s = "❤️🧡💛💚💙💜";
     /// assert_eq!(s.len(), 26);
     /// assert!(!s.is_char_boundary(13));
@@ -405,7 +404,8 @@ impl str {
     /// assert_eq!(closest, 10);
     /// assert_eq!(&s[..closest], "❤️🧡");
     /// ```
-    #[unstable(feature = "round_char_boundary", issue = "93743")]
+    #[stable(feature = "round_char_boundary", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "round_char_boundary", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn floor_char_boundary(&self, index: usize) -> usize {
         if index >= self.len() {
@@ -439,7 +439,6 @@ impl str {
     /// # Examples
     ///
     /// ```
-    /// #![feature(round_char_boundary)]
     /// let s = "❤️🧡💛💚💙💜";
     /// assert_eq!(s.len(), 26);
     /// assert!(!s.is_char_boundary(13));
@@ -448,7 +447,8 @@ impl str {
     /// assert_eq!(closest, 14);
     /// assert_eq!(&s[..closest], "❤️🧡💛");
     /// ```
-    #[unstable(feature = "round_char_boundary", issue = "93743")]
+    #[stable(feature = "round_char_boundary", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "round_char_boundary", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn ceil_char_boundary(&self, index: usize) -> usize {
         if index >= self.len() {

std/src/lib.rs

@@ -263,7 +263,6 @@
     all(target_vendor = "fortanix", target_env = "sgx"),
     feature(slice_index_methods, coerce_unsized, sgx_platform)
 )]
-#![cfg_attr(any(windows, target_os = "uefi"), feature(round_char_boundary))]
 #![cfg_attr(target_family = "wasm", feature(stdarch_wasm_atomic_wait))]
 #![cfg_attr(target_arch = "wasm64", feature(simd_wasm64))]
 //