/// ```

///

/// ```

/// #![feature(const_cstr_from_ptr)]

///

/// use std::ffi::{c_char, CStr};

///

/// const HELLO_PTR: *const c_char = {

#[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`.

#[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

}

/// The pointer must point to a valid buffer that contains a NUL terminator. The NUL must be

/// located within `isize::MAX` from `ptr`.

#[inline]

#[unstable(feature = "cstr_internals", issue = "none")]

#[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;