Rollup of 6 pull requests

library/alloc/src/string.rs

@@ -1290,11 +1290,11 @@ impl String {
     /// Basic usage:
     ///
     /// ```
-    /// let mut s = String::from("foo");
+    /// let mut s = String::from("abč");
     ///
-    /// assert_eq!(s.pop(), Some('o'));
-    /// assert_eq!(s.pop(), Some('o'));
-    /// assert_eq!(s.pop(), Some('f'));
+    /// assert_eq!(s.pop(), Some('č'));
+    /// assert_eq!(s.pop(), Some('b'));
+    /// assert_eq!(s.pop(), Some('a'));
     ///
     /// assert_eq!(s.pop(), None);
     /// ```
@@ -1324,11 +1324,11 @@ impl String {
     /// Basic usage:
     ///
     /// ```
-    /// let mut s = String::from("foo");
+    /// let mut s = String::from("abç");
     ///
-    /// assert_eq!(s.remove(0), 'f');
-    /// assert_eq!(s.remove(1), 'o');
-    /// assert_eq!(s.remove(0), 'o');
+    /// assert_eq!(s.remove(0), 'a');
+    /// assert_eq!(s.remove(1), 'ç');
+    /// assert_eq!(s.remove(0), 'b');
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]

library/alloc/src/vec/mod.rs

@@ -2961,7 +2961,7 @@ impl<T, A: Allocator> Vec<T, A> {
 /// [`copy_from_slice`]: slice::copy_from_slice
 #[cfg(not(no_global_oom_handling))]
 #[stable(feature = "extend_ref", since = "1.2.0")]
-impl<'a, T: Copy + 'a, A: Allocator + 'a> Extend<&'a T> for Vec<T, A> {
+impl<'a, T: Copy + 'a, A: Allocator> Extend<&'a T> for Vec<T, A> {
     fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I) {
         self.spec_extend(iter.into_iter())
     }

library/alloc/src/vec/spec_extend.rs

@@ -36,7 +36,7 @@ impl<T, A: Allocator> SpecExtend<T, IntoIter<T>> for Vec<T, A> {
     }
 }
 
-impl<'a, T: 'a, I, A: Allocator + 'a> SpecExtend<&'a T, I> for Vec<T, A>
+impl<'a, T: 'a, I, A: Allocator> SpecExtend<&'a T, I> for Vec<T, A>
 where
     I: Iterator<Item = &'a T>,
     T: Clone,
@@ -46,7 +46,7 @@ where
     }
 }
 
-impl<'a, T: 'a, A: Allocator + 'a> SpecExtend<&'a T, slice::Iter<'a, T>> for Vec<T, A>
+impl<'a, T: 'a, A: Allocator> SpecExtend<&'a T, slice::Iter<'a, T>> for Vec<T, A>
 where
     T: Copy,
 {

library/core/src/ffi/c_str.rs

@@ -256,7 +256,7 @@ impl CStr {
     #[inline]
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_unstable(feature = "const_cstr_from_ptr", issue = "101719")]
+    #[rustc_const_unstable(feature = "const_cstr_from_ptr", issue = "113219")]
     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

library/core/src/ffi/mod.rs

@@ -52,11 +52,6 @@ macro_rules! type_alias {
 }
 
 type_alias! { "c_char.md", c_char = c_char_definition::c_char, NonZero_c_char = c_char_definition::NonZero_c_char;
-// Make this type alias appear cfg-dependent so that Clippy does not suggest
-// replacing `0 as c_char` with `0_i8`/`0_u8`. This #[cfg(all())] can be removed
-// after the false positive in https://github.com/rust-lang/rust-clippy/issues/8093
-// is fixed.
-#[cfg(all())]
 #[doc(cfg(all()))] }
 
 type_alias! { "c_schar.md", c_schar = i8, NonZero_c_schar = NonZeroI8; }

library/std/src/ffi/os_str.rs

@@ -141,6 +141,51 @@ impl OsString {
         OsString { inner: Buf::from_string(String::new()) }
     }
 
+    /// Converts bytes to an `OsString` without checking that the bytes contains
+    /// valid [`OsStr`]-encoded data.
+    ///
+    /// The byte encoding is an unspecified, platform-specific, self-synchronizing superset of UTF-8.
+    /// By being a self-synchronizing superset of UTF-8, this encoding is also a superset of 7-bit
+    /// ASCII.
+    ///
+    /// See the [module's toplevel documentation about conversions][conversions] for safe,
+    /// cross-platform [conversions] from/to native representations.
+    ///
+    /// # Safety
+    ///
+    /// As the encoding is unspecified, callers must pass in bytes that originated as a mixture of
+    /// validated UTF-8 and bytes from [`OsStr::as_os_str_bytes`] from within the same rust version
+    /// built for the same target platform.  For example, reconstructing an `OsString` from bytes sent
+    /// over the network or stored in a file will likely violate these safety rules.
+    ///
+    /// Due to the encoding being self-synchronizing, the bytes from [`OsStr::as_os_str_bytes`] can be
+    /// split either immediately before or immediately after any valid non-empty UTF-8 substring.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// #![feature(os_str_bytes)]
+    ///
+    /// use std::ffi::OsStr;
+    ///
+    /// let os_str = OsStr::new("Mary had a little lamb");
+    /// let bytes = os_str.as_os_str_bytes();
+    /// let words = bytes.split(|b| *b == b' ');
+    /// let words: Vec<&OsStr> = words.map(|word| {
+    ///     // SAFETY:
+    ///     // - Each `word` only contains content that originated from `OsStr::as_os_str_bytes`
+    ///     // - Only split with ASCII whitespace which is a non-empty UTF-8 substring
+    ///     unsafe { OsStr::from_os_str_bytes_unchecked(word) }
+    /// }).collect();
+    /// ```
+    ///
+    /// [conversions]: super#conversions
+    #[inline]
+    #[unstable(feature = "os_str_bytes", issue = "111544")]
+    pub unsafe fn from_os_str_bytes_unchecked(bytes: Vec<u8>) -> Self {
+        OsString { inner: Buf::from_os_str_bytes_unchecked(bytes) }
+    }
+
     /// Converts to an [`OsStr`] slice.
     ///
     /// # Examples
@@ -159,6 +204,26 @@ impl OsString {
         self
     }
 
+    /// Converts the `OsString` into a byte slice.  To convert the byte slice back into an
+    /// `OsString`, use the [`OsStr::from_os_str_bytes_unchecked`] function.
+    ///
+    /// The byte encoding is an unspecified, platform-specific, self-synchronizing superset of UTF-8.
+    /// By being a self-synchronizing superset of UTF-8, this encoding is also a superset of 7-bit
+    /// ASCII.
+    ///
+    /// Note: As the encoding is unspecified, any sub-slice of bytes that is not valid UTF-8 should
+    /// be treated as opaque and only comparable within the same rust version built for the same
+    /// target platform.  For example, sending the bytes over the network or storing it in a file
+    /// will likely result in incompatible data.  See [`OsString`] for more encoding details
+    /// and [`std::ffi`] for platform-specific, specified conversions.
+    ///
+    /// [`std::ffi`]: crate::ffi
+    #[inline]
+    #[unstable(feature = "os_str_bytes", issue = "111544")]
+    pub fn into_os_str_bytes(self) -> Vec<u8> {
+        self.inner.into_os_str_bytes()
+    }
+
     /// Converts the `OsString` into a [`String`] if it contains valid Unicode data.
     ///
     /// On failure, ownership of the original `OsString` is returned.

library/std/src/os/raw/mod.rs

@@ -9,11 +9,6 @@ macro_rules! alias_core_ffi {
     ($($t:ident)*) => {$(
         #[stable(feature = "raw_os", since = "1.1.0")]
         #[doc = include_str!(concat!("../../../../core/src/ffi/", stringify!($t), ".md"))]
-        // Make this type alias appear cfg-dependent so that Clippy does not suggest
-        // replacing expressions like `0 as c_char` with `0_i8`/`0_u8`. This #[cfg(all())] can be
-        // removed after the false positive in https://github.com/rust-lang/rust-clippy/issues/8093
-        // is fixed.
-        #[cfg(all())]
         #[doc(cfg(all()))]
         pub type $t = core::ffi::$t;
     )*}

library/std/src/os/unix/fs.rs

@@ -149,7 +149,36 @@ pub trait FileExt {
     /// Note that similar to [`File::write`], it is not an error to return a
     /// short write.
     ///
+    /// # Bug
+    /// On some systems, `write_at` utilises [`pwrite64`] to write to files.
+    /// However, this syscall has a [bug] where files opened with the `O_APPEND`
+    /// flag fail to respect the offset parameter, always appending to the end
+    /// of the file instead.
+    ///
+    /// It is possible to inadvertantly set this flag, like in the example below.
+    /// Therefore, it is important to be vigilant while changing options to mitigate
+    /// unexpected behaviour.
+    ///
+    /// ```no_run
+    /// use std::fs::File;
+    /// use std::io;
+    /// use std::os::unix::prelude::FileExt;
+    ///
+    /// fn main() -> io::Result<()> {
+    ///     // Open a file with the append option (sets the `O_APPEND` flag)
+    ///     let file = File::options().append(true).open("foo.txt")?;
+    ///
+    ///     // We attempt to write at offset 10; instead appended to EOF
+    ///     file.write_at(b"sushi", 10)?;
+    ///
+    ///     // foo.txt is 5 bytes long instead of 15
+    ///     Ok(())
+    /// }
+    /// ```
+    ///
     /// [`File::write`]: fs::File::write
+    /// [`pwrite64`]: https://man7.org/linux/man-pages/man2/pwrite.2.html
+    /// [bug]: https://man7.org/linux/man-pages/man2/pwrite.2.html#BUGS
     ///
     /// # Examples
     ///
@@ -159,7 +188,7 @@ pub trait FileExt {
     /// use std::os::unix::prelude::FileExt;
     ///
     /// fn main() -> io::Result<()> {
-    ///     let file = File::open("foo.txt")?;
+    ///     let file = File::create("foo.txt")?;
     ///
     ///     // We now write at the offset 10.
     ///     file.write_at(b"sushi", 10)?;

library/std/src/sys/unix/os_str.rs

@@ -96,6 +96,16 @@ impl AsInner<[u8]> for Buf {
 }
 
 impl Buf {
+    #[inline]
+    pub fn into_os_str_bytes(self) -> Vec<u8> {
+        self.inner
+    }
+
+    #[inline]
+    pub unsafe fn from_os_str_bytes_unchecked(s: Vec<u8>) -> Self {
+        Self { inner: s }
+    }
+
     pub fn from_string(s: String) -> Buf {
         Buf { inner: s.into_bytes() }
     }

library/std/src/sys/windows/os_str.rs

@@ -63,6 +63,16 @@ impl fmt::Display for Slice {
 }
 
 impl Buf {
+    #[inline]
+    pub fn into_os_str_bytes(self) -> Vec<u8> {
+        self.inner.into_bytes()
+    }
+
+    #[inline]
+    pub unsafe fn from_os_str_bytes_unchecked(s: Vec<u8>) -> Self {
+        Self { inner: Wtf8Buf::from_bytes_unchecked(s) }
+    }
+
     pub fn with_capacity(capacity: usize) -> Buf {
         Buf { inner: Wtf8Buf::with_capacity(capacity) }
     }

library/std/src/sys_common/wtf8.rs

@@ -182,6 +182,15 @@ impl Wtf8Buf {
         Wtf8Buf { bytes: Vec::with_capacity(capacity), is_known_utf8: true }
     }
 
+    /// Creates a WTF-8 string from a WTF-8 byte vec.
+    ///
+    /// Since the byte vec is not checked for valid WTF-8, this functions is
+    /// marked unsafe.
+    #[inline]
+    pub unsafe fn from_bytes_unchecked(value: Vec<u8>) -> Wtf8Buf {
+        Wtf8Buf { bytes: value, is_known_utf8: false }
+    }
+
     /// Creates a WTF-8 string from a UTF-8 `String`.
     ///
     /// This takes ownership of the `String` and does not copy.
@@ -402,6 +411,12 @@ impl Wtf8Buf {
         self.bytes.truncate(new_len)
     }
 
+    /// Consumes the WTF-8 string and tries to convert it to a vec of bytes.
+    #[inline]
+    pub fn into_bytes(self) -> Vec<u8> {
+        self.bytes
+    }
+
     /// Consumes the WTF-8 string and tries to convert it to UTF-8.
     ///
     /// This does not copy the data.