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Stabilize const_cstr_methods #107624

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Jun 30, 2023
Merged

Stabilize const_cstr_methods #107624

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17 changes: 10 additions & 7 deletions library/core/src/ffi/c_str.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -241,7 +241,7 @@ impl CStr {
/// ```
///
/// ```
/// #![feature(const_cstr_methods)]
/// #![feature(const_cstr_from_ptr)]
///
/// use std::ffi::{c_char, CStr};
///
Expand All @@ -256,7 +256,7 @@ impl CStr {
#[inline]
#[must_use]
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_cstr_methods", issue = "101719")]
#[rustc_const_unstable(feature = "const_cstr_from_ptr", issue = "101719")]
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 of size less than `isize::MAX`, whose
Expand Down Expand Up @@ -377,7 +377,7 @@ impl CStr {
/// assert!(cstr.is_err());
/// ```
#[stable(feature = "cstr_from_bytes", since = "1.10.0")]
#[rustc_const_unstable(feature = "const_cstr_methods", issue = "101719")]
#[rustc_const_stable(feature = "const_cstr_methods", since = "CURRENT_RUSTC_VERSION")]
pub const fn from_bytes_with_nul(bytes: &[u8]) -> Result<&Self, FromBytesWithNulError> {
let nul_pos = memchr::memchr(0, bytes);
match nul_pos {
Expand Down Expand Up @@ -561,10 +561,12 @@ impl CStr {
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn to_bytes(&self) -> &[u8] {
#[rustc_const_stable(feature = "const_cstr_methods", since = "CURRENT_RUSTC_VERSION")]
pub const fn to_bytes(&self) -> &[u8] {
let bytes = self.to_bytes_with_nul();
// FIXME(const-hack) replace with range index
// SAFETY: to_bytes_with_nul returns slice with length at least 1
unsafe { bytes.get_unchecked(..bytes.len() - 1) }
unsafe { slice::from_raw_parts(bytes.as_ptr(), bytes.len() - 1) }
}

/// Converts this C string to a byte slice containing the trailing 0 byte.
Expand All @@ -588,7 +590,7 @@ impl CStr {
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_cstr_methods", issue = "101719")]
#[rustc_const_stable(feature = "const_cstr_methods", since = "CURRENT_RUSTC_VERSION")]
pub const fn to_bytes_with_nul(&self) -> &[u8] {
// SAFETY: Transmuting a slice of `c_char`s to a slice of `u8`s
// is safe on all supported targets.
Expand All @@ -612,7 +614,8 @@ impl CStr {
/// assert_eq!(cstr.to_str(), Ok("foo"));
/// ```
#[stable(feature = "cstr_to_str", since = "1.4.0")]
pub fn to_str(&self) -> Result<&str, str::Utf8Error> {
#[rustc_const_stable(feature = "const_cstr_methods", since = "CURRENT_RUSTC_VERSION")]
pub const fn to_str(&self) -> Result<&str, str::Utf8Error> {
// N.B., when `CStr` is changed to perform the length check in `.to_bytes()`
// instead of in `from_ptr()`, it may be worth considering if this should
// be rewritten to do the UTF-8 check inline with the length calculation
Expand Down
1 change: 0 additions & 1 deletion library/core/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -113,7 +113,6 @@
#![feature(const_caller_location)]
#![feature(const_cell_into_inner)]
#![feature(const_char_from_u32_unchecked)]
#![feature(const_cstr_methods)]
#![feature(const_discriminant)]
#![feature(const_eval_select)]
#![feature(const_exact_div)]
Expand Down