Stabilize const_cstr_from_ptr (CStr::from_ptr, CStr::count_bytes)

Author: dtolnay

core/src/ffi/c_str.rs

@@ -263,8 +263,6 @@ impl CStr {
     /// ```
     ///
     /// ```
-    /// #![feature(const_cstr_from_ptr)]
-    ///
     /// use std::ffi::{c_char, CStr};
     ///
     /// const HELLO_PTR: *const c_char = {
@@ -280,7 +278,7 @@ impl CStr {
     #[inline] // inline is necessary for codegen to see strlen.
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_unstable(feature = "const_cstr_from_ptr", issue = "113219")]
+    #[rustc_const_stable(feature = "const_cstr_from_ptr", since = "CURRENT_RUSTC_VERSION")]
     pub const unsafe fn from_ptr<'a>(ptr: *const c_char) -> &'a CStr {
         // SAFETY: The caller has provided a pointer that points to a valid C
         // string with a NUL terminator less than `isize::MAX` from `ptr`.
@@ -542,7 +540,7 @@ impl CStr {
     #[must_use]
     #[doc(alias("len", "strlen"))]
     #[stable(feature = "cstr_count_bytes", since = "1.79.0")]
-    #[rustc_const_unstable(feature = "const_cstr_from_ptr", issue = "113219")]
+    #[rustc_const_stable(feature = "const_cstr_from_ptr", since = "CURRENT_RUSTC_VERSION")]
     pub const fn count_bytes(&self) -> usize {
         self.inner.len() - 1
     }
@@ -742,6 +740,8 @@ impl AsRef<CStr> for CStr {
 /// The pointer must point to a valid buffer that contains a NUL terminator. The NUL must be
 /// located within `isize::MAX` from `ptr`.
 #[inline]
+#[rustc_const_stable(feature = "const_cstr_from_ptr", since = "CURRENT_RUSTC_VERSION")]
+#[rustc_allow_const_fn_unstable(const_eval_select)]
 const unsafe fn const_strlen(ptr: *const c_char) -> usize {
     const fn strlen_ct(s: *const c_char) -> usize {
         let mut len = 0;