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stabilize String::into_chars #163816

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stabilize String::into_chars #163816

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24 changes: 8 additions & 16 deletions library/alloc/src/string.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2058,8 +2058,6 @@ impl String {
/// Basic usage:
///
/// ```
/// #![feature(string_into_chars)]
///
/// let word = String::from("goodbye");
///
/// let mut chars = word.into_chars();
Expand All @@ -2078,8 +2076,6 @@ impl String {
/// Remember, [`char`]s might not match your intuition about characters:
///
/// ```
/// #![feature(string_into_chars)]
///
/// let y = String::from("y̆");
///
/// let mut chars = y.into_chars();
Expand All @@ -2093,7 +2089,7 @@ impl String {
/// [`char`]: prim@char
#[inline]
#[must_use = "`self` will be dropped if the result is not used"]
#[unstable(feature = "string_into_chars", issue = "133125")]
#[stable(feature = "string_into_chars", since = "CURRENT_RUSTC_VERSION")]
pub fn into_chars(self) -> IntoChars {
IntoChars { bytes: self.into_bytes().into_iter() }
}
Expand Down Expand Up @@ -3439,12 +3435,12 @@ impl fmt::Write for String {
/// [`into_chars`]: String::into_chars
#[cfg_attr(not(no_global_oom_handling), derive(Clone))]
#[must_use = "iterators are lazy and do nothing unless consumed"]
#[unstable(feature = "string_into_chars", issue = "133125")]
#[stable(feature = "string_into_chars", since = "CURRENT_RUSTC_VERSION")]
pub struct IntoChars {
bytes: vec::IntoIter<u8>,
}
Comment on lines 3439 to 3441

@clarfonthey clarfonthey Oct 5, 2026 •
edited by rustbot
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Since this is just a wrapper over vec::IntoIter, we could pretty easily derive(Clone) and support it. I would say that's useful since cloning iterators is pretty useful for debugging, even if it would allocate a copy here.

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@malezjaa malezjaa Oct 5, 2026

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Doesn't it already have Clone?

#[cfg_attr(not(no_global_oom_handling), derive(Clone))]

Or did you mean that it should always derive(Clone)?

@clarfonthey clarfonthey Oct 5, 2026

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Oh, I totally missed that line. You just didn't include it in the public API in the description is why I was confused.

@malezjaa malezjaa Oct 5, 2026

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Sorry, I just copied the output from cargo unstable-api which didn't include the clone 😅 It's probably because it was in #[cfg_attr].


#[unstable(feature = "string_into_chars", issue = "133125")]
#[stable(feature = "string_into_chars", since = "CURRENT_RUSTC_VERSION")]
impl fmt::Debug for IntoChars {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_tuple("IntoChars").field(&self.as_str()).finish()
Expand All @@ -3457,8 +3453,6 @@ impl IntoChars {
/// # Examples
///
/// ```
/// #![feature(string_into_chars)]
///
/// let mut chars = String::from("abc").into_chars();
///
/// assert_eq!(chars.as_str(), "abc");
Expand All @@ -3468,7 +3462,7 @@ impl IntoChars {
/// chars.next();
/// assert_eq!(chars.as_str(), "");
/// ```
#[unstable(feature = "string_into_chars", issue = "133125")]
#[stable(feature = "string_into_chars", since = "CURRENT_RUSTC_VERSION")]
#[must_use]
#[inline]
pub fn as_str(&self) -> &str {
Expand All @@ -3481,8 +3475,6 @@ impl IntoChars {
/// # Examples
///
/// ```
/// #![feature(string_into_chars)]
///
/// let chars = String::from("abc").into_chars();
/// assert_eq!(chars.into_string(), "abc");
///
Expand All @@ -3491,7 +3483,7 @@ impl IntoChars {
/// assert_eq!(chars.into_string(), "ef");
/// ```
#[cfg(not(no_global_oom_handling))]
#[unstable(feature = "string_into_chars", issue = "133125")]
#[stable(feature = "string_into_chars", since = "CURRENT_RUSTC_VERSION")]
#[inline]
pub fn into_string(self) -> String {
// SAFETY: `bytes` are kept in UTF-8 form, only removing whole `char`s at a time.
Expand All @@ -3504,7 +3496,7 @@ impl IntoChars {
}
}

#[unstable(feature = "string_into_chars", issue = "133125")]
#[stable(feature = "string_into_chars", since = "CURRENT_RUSTC_VERSION")]
impl Iterator for IntoChars {
type Item = char;

Expand Down Expand Up @@ -3538,7 +3530,7 @@ impl Iterator for IntoChars {
}
}

#[unstable(feature = "string_into_chars", issue = "133125")]
#[stable(feature = "string_into_chars", since = "CURRENT_RUSTC_VERSION")]
impl DoubleEndedIterator for IntoChars {
#[inline]
fn next_back(&mut self) -> Option<char> {
Expand All @@ -3555,7 +3547,7 @@ impl DoubleEndedIterator for IntoChars {
}
}

#[unstable(feature = "string_into_chars", issue = "133125")]
#[stable(feature = "string_into_chars", since = "CURRENT_RUSTC_VERSION")]
impl FusedIterator for IntoChars {}

/// A draining iterator for `String`.
Expand Down
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