Move std::io::ErrorKind to core::io

Move `std::io::ErrorKind` to `core::io` * Update `rustdoc-html` tests for the new path * Add `core_io` feature to control stability. This replaces the use of `core_io_borrowed_buf` on the `core::io` module itself. * Re-export `core::io::ErrorKind` in `std::io::error`
2026-04-27 18:57:42 +03:00 · 2026-04-15 08:50:00 +10:00
parent 6960e7c958
commit fe2b39f064
11 changed files with 411 additions and 380 deletions
@@ -0,0 +1,372 @@
+#![unstable(feature = "core_io", issue = "154046")]
+
+use crate::fmt;
+
+/// A list specifying general categories of I/O error.
+///
+/// This list is intended to grow over time and it is not recommended to
+/// exhaustively match against it.
+///
+/// # Handling errors and matching on `ErrorKind`
+///
+/// In application code, use `match` for the `ErrorKind` values you are
+/// expecting; use `_` to match "all other errors".
+///
+/// In comprehensive and thorough tests that want to verify that a test doesn't
+/// return any known incorrect error kind, you may want to cut-and-paste the
+/// current full list of errors from here into your test code, and then match
+/// `_` as the correct case. This seems counterintuitive, but it will make your
+/// tests more robust. In particular, if you want to verify that your code does
+/// produce an unrecognized error kind, the robust solution is to check for all
+/// the recognized error kinds and fail in those cases.
+#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
+#[stable(feature = "rust1", since = "1.0.0")]
+#[cfg_attr(not(test), rustc_diagnostic_item = "io_errorkind")]
+#[allow(deprecated)]
+#[non_exhaustive]
+pub enum ErrorKind {
+    /// An entity was not found, often a file.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    NotFound,
+    /// The operation lacked the necessary privileges to complete.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    PermissionDenied,
+    /// The connection was refused by the remote server.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    ConnectionRefused,
+    /// The connection was reset by the remote server.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    ConnectionReset,
+    /// The remote host is not reachable.
+    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
+    HostUnreachable,
+    /// The network containing the remote host is not reachable.
+    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
+    NetworkUnreachable,
+    /// The connection was aborted (terminated) by the remote server.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    ConnectionAborted,
+    /// The network operation failed because it was not connected yet.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    NotConnected,
+    /// A socket address could not be bound because the address is already in
+    /// use elsewhere.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    AddrInUse,
+    /// A nonexistent interface was requested or the requested address was not
+    /// local.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    AddrNotAvailable,
+    /// The system's networking is down.
+    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
+    NetworkDown,
+    /// The operation failed because a pipe was closed.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    BrokenPipe,
+    /// An entity already exists, often a file.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    AlreadyExists,
+    /// The operation needs to block to complete, but the blocking operation was
+    /// requested to not occur.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    WouldBlock,
+    /// A filesystem object is, unexpectedly, not a directory.
+    ///
+    /// For example, a filesystem path was specified where one of the intermediate directory
+    /// components was, in fact, a plain file.
+    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
+    NotADirectory,
+    /// The filesystem object is, unexpectedly, a directory.
+    ///
+    /// A directory was specified when a non-directory was expected.
+    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
+    IsADirectory,
+    /// A non-empty directory was specified where an empty directory was expected.
+    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
+    DirectoryNotEmpty,
+    /// The filesystem or storage medium is read-only, but a write operation was attempted.
+    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
+    ReadOnlyFilesystem,
+    /// Loop in the filesystem or IO subsystem; often, too many levels of symbolic links.
+    ///
+    /// There was a loop (or excessively long chain) resolving a filesystem object
+    /// or file IO object.
+    ///
+    /// On Unix this is usually the result of a symbolic link loop; or, of exceeding the
+    /// system-specific limit on the depth of symlink traversal.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    FilesystemLoop,
+    /// Stale network file handle.
+    ///
+    /// With some network filesystems, notably NFS, an open file (or directory) can be invalidated
+    /// by problems with the network or server.
+    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
+    StaleNetworkFileHandle,
+    /// A parameter was incorrect.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    InvalidInput,
+    /// Data not valid for the operation were encountered.
+    ///
+    /// Unlike [`InvalidInput`], this typically means that the operation
+    /// parameters were valid, however the error was caused by malformed
+    /// input data.
+    ///
+    /// For example, a function that reads a file into a string will error with
+    /// `InvalidData` if the file's contents are not valid UTF-8.
+    ///
+    /// [`InvalidInput`]: ErrorKind::InvalidInput
+    #[stable(feature = "io_invalid_data", since = "1.2.0")]
+    InvalidData,
+    /// The I/O operation's timeout expired, causing it to be canceled.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    TimedOut,
+    /// An error returned when an operation could not be completed because a
+    /// call to an underlying writer returned [`Ok(0)`].
+    ///
+    /// This typically means that an operation could only succeed if it wrote a
+    /// particular number of bytes but only a smaller number of bytes could be
+    /// written.
+    ///
+    /// [`Ok(0)`]: Ok
+    #[stable(feature = "rust1", since = "1.0.0")]
+    WriteZero,
+    /// The underlying storage (typically, a filesystem) is full.
+    ///
+    /// This does not include out of quota errors.
+    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
+    StorageFull,
+    /// Seek on unseekable file.
+    ///
+    /// Seeking was attempted on an open file handle which is not suitable for seeking - for
+    /// example, on Unix, a named pipe opened with `File::open`.
+    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
+    NotSeekable,
+    /// Filesystem quota or some other kind of quota was exceeded.
+    #[stable(feature = "io_error_quota_exceeded", since = "1.85.0")]
+    QuotaExceeded,
+    /// File larger than allowed or supported.
+    ///
+    /// This might arise from a hard limit of the underlying filesystem or file access API, or from
+    /// an administratively imposed resource limitation.  Simple disk full, and out of quota, have
+    /// their own errors.
+    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
+    FileTooLarge,
+    /// Resource is busy.
+    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
+    ResourceBusy,
+    /// Executable file is busy.
+    ///
+    /// An attempt was made to write to a file which is also in use as a running program.  (Not all
+    /// operating systems detect this situation.)
+    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
+    ExecutableFileBusy,
+    /// Deadlock (avoided).
+    ///
+    /// A file locking operation would result in deadlock.  This situation is typically detected, if
+    /// at all, on a best-effort basis.
+    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
+    Deadlock,
+    /// Cross-device or cross-filesystem (hard) link or rename.
+    #[stable(feature = "io_error_crosses_devices", since = "1.85.0")]
+    CrossesDevices,
+    /// Too many (hard) links to the same filesystem object.
+    ///
+    /// The filesystem does not support making so many hardlinks to the same file.
+    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
+    TooManyLinks,
+    /// A filename was invalid.
+    ///
+    /// This error can also occur if a length limit for a name was exceeded.
+    #[stable(feature = "io_error_invalid_filename", since = "1.87.0")]
+    InvalidFilename,
+    /// Program argument list too long.
+    ///
+    /// When trying to run an external program, a system or process limit on the size of the
+    /// arguments would have been exceeded.
+    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
+    ArgumentListTooLong,
+    /// This operation was interrupted.
+    ///
+    /// Interrupted operations can typically be retried.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    Interrupted,
+
+    /// This operation is unsupported on this platform.
+    ///
+    /// This means that the operation can never succeed.
+    #[stable(feature = "unsupported_error", since = "1.53.0")]
+    Unsupported,
+
+    // ErrorKinds which are primarily categorisations for OS error
+    // codes should be added above.
+    //
+    /// An error returned when an operation could not be completed because an
+    /// "end of file" was reached prematurely.
+    ///
+    /// This typically means that an operation could only succeed if it read a
+    /// particular number of bytes but only a smaller number of bytes could be
+    /// read.
+    #[stable(feature = "read_exact", since = "1.6.0")]
+    UnexpectedEof,
+
+    /// An operation could not be completed, because it failed
+    /// to allocate enough memory.
+    #[stable(feature = "out_of_memory_error", since = "1.54.0")]
+    OutOfMemory,
+
+    /// The operation was partially successful and needs to be checked
+    /// later on due to not blocking.
+    #[unstable(feature = "io_error_inprogress", issue = "130840")]
+    InProgress,
+
+    // "Unusual" error kinds which do not correspond simply to (sets
+    // of) OS error codes, should be added just above this comment.
+    // `Other` and `Uncategorized` should remain at the end:
+    //
+    /// A custom error that does not fall under any other I/O error kind.
+    ///
+    /// This can be used to construct your own errors that do not match any
+    /// [`ErrorKind`].
+    ///
+    /// This [`ErrorKind`] is not used by the standard library.
+    ///
+    /// Errors from the standard library that do not fall under any of the I/O
+    /// error kinds cannot be `match`ed on, and will only match a wildcard (`_`) pattern.
+    /// New [`ErrorKind`]s might be added in the future for some of those.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    Other,
+
+    /// Any I/O error from the standard library that's not part of this list.
+    ///
+    /// Errors that are `Uncategorized` now may move to a different or a new
+    /// [`ErrorKind`] variant in the future. It is not recommended to match
+    /// an error against `Uncategorized`; use a wildcard match (`_`) instead.
+    #[unstable(feature = "io_error_uncategorized", issue = "none")]
+    #[doc(hidden)]
+    Uncategorized,
+}
+
+impl ErrorKind {
+    pub(crate) const fn as_str(&self) -> &'static str {
+        use ErrorKind::*;
+        match *self {
+            // tidy-alphabetical-start
+            AddrInUse => "address in use",
+            AddrNotAvailable => "address not available",
+            AlreadyExists => "entity already exists",
+            ArgumentListTooLong => "argument list too long",
+            BrokenPipe => "broken pipe",
+            ConnectionAborted => "connection aborted",
+            ConnectionRefused => "connection refused",
+            ConnectionReset => "connection reset",
+            CrossesDevices => "cross-device link or rename",
+            Deadlock => "deadlock",
+            DirectoryNotEmpty => "directory not empty",
+            ExecutableFileBusy => "executable file busy",
+            FileTooLarge => "file too large",
+            FilesystemLoop => "filesystem loop or indirection limit (e.g. symlink loop)",
+            HostUnreachable => "host unreachable",
+            InProgress => "in progress",
+            Interrupted => "operation interrupted",
+            InvalidData => "invalid data",
+            InvalidFilename => "invalid filename",
+            InvalidInput => "invalid input parameter",
+            IsADirectory => "is a directory",
+            NetworkDown => "network down",
+            NetworkUnreachable => "network unreachable",
+            NotADirectory => "not a directory",
+            NotConnected => "not connected",
+            NotFound => "entity not found",
+            NotSeekable => "seek on unseekable file",
+            Other => "other error",
+            OutOfMemory => "out of memory",
+            PermissionDenied => "permission denied",
+            QuotaExceeded => "quota exceeded",
+            ReadOnlyFilesystem => "read-only filesystem or storage medium",
+            ResourceBusy => "resource busy",
+            StaleNetworkFileHandle => "stale network file handle",
+            StorageFull => "no storage space",
+            TimedOut => "timed out",
+            TooManyLinks => "too many links",
+            Uncategorized => "uncategorized error",
+            UnexpectedEof => "unexpected end of file",
+            Unsupported => "unsupported",
+            WouldBlock => "operation would block",
+            WriteZero => "write zero",
+            // tidy-alphabetical-end
+        }
+    }
+
+    // This compiles to the same code as the check+transmute, but doesn't require
+    // unsafe, or to hard-code max ErrorKind or its size in a way the compiler
+    // couldn't verify.
+    #[inline]
+    #[unstable(feature = "core_io_internals", reason = "exposed only for libstd", issue = "none")]
+    #[doc(hidden)]
+    pub const fn from_prim(ek: u32) -> Option<Self> {
+        macro_rules! from_prim {
+            ($prim:expr => $Enum:ident { $($Variant:ident),* $(,)? }) => {{
+                // Force a compile error if the list gets out of date.
+                const _: fn(e: $Enum) = |e: $Enum| match e {
+                    $($Enum::$Variant => (),)*
+                };
+                match $prim {
+                    $(v if v == ($Enum::$Variant as _) => Some($Enum::$Variant),)*
+                    _ => None,
+                }
+            }}
+        }
+        from_prim!(ek => ErrorKind {
+            NotFound,
+            PermissionDenied,
+            ConnectionRefused,
+            ConnectionReset,
+            HostUnreachable,
+            NetworkUnreachable,
+            ConnectionAborted,
+            NotConnected,
+            AddrInUse,
+            AddrNotAvailable,
+            NetworkDown,
+            BrokenPipe,
+            AlreadyExists,
+            WouldBlock,
+            NotADirectory,
+            IsADirectory,
+            DirectoryNotEmpty,
+            ReadOnlyFilesystem,
+            FilesystemLoop,
+            StaleNetworkFileHandle,
+            InvalidInput,
+            InvalidData,
+            TimedOut,
+            WriteZero,
+            StorageFull,
+            NotSeekable,
+            QuotaExceeded,
+            FileTooLarge,
+            ResourceBusy,
+            ExecutableFileBusy,
+            Deadlock,
+            CrossesDevices,
+            TooManyLinks,
+            InvalidFilename,
+            ArgumentListTooLong,
+            Interrupted,
+            Other,
+            UnexpectedEof,
+            Unsupported,
+            OutOfMemory,
+            InProgress,
+            Uncategorized,
+        })
+    }
+}
+
+#[stable(feature = "io_errorkind_display", since = "1.60.0")]
+impl fmt::Display for ErrorKind {
+    /// Shows a human-readable description of the `ErrorKind`.
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt.write_str(self.as_str())
+    }
+}
@@ -1,6 +1,9 @@
 //! Traits, helpers, and type definitions for core I/O functionality.

 mod borrowed_buf;
+mod error;

 #[unstable(feature = "core_io_borrowed_buf", issue = "117693")]
 pub use self::borrowed_buf::{BorrowedBuf, BorrowedCursor};
+#[unstable(feature = "core_io", issue = "154046")]
+pub use self::error::ErrorKind;
@@ -305,7 +305,7 @@ pub mod autodiff {
 pub mod cell;
 pub mod char;
 pub mod ffi;
-#[unstable(feature = "core_io_borrowed_buf", issue = "117693")]
+#[unstable(feature = "core_io", issue = "154046")]
 pub mod io;
 pub mod iter;
 pub mod net;
@@ -36,6 +36,7 @@
 #![feature(const_unsigned_bigint_helpers)]
 #![feature(core_intrinsics)]
 #![feature(core_intrinsics_fallbacks)]
+#![feature(core_io)]
 #![feature(core_io_borrowed_buf)]
 #![feature(core_private_bignum)]
 #![feature(core_private_diy_float)]
@@ -1,6 +1,9 @@
 #[cfg(test)]
 mod tests;

+#[stable(feature = "rust1", since = "1.0.0")]
+pub use core::io::ErrorKind;
+
 // On 64-bit platforms, `io::Error` may use a bit-packed representation to
 // reduce size. However, this representation assumes that error codes are
 // always 32-bit wide.
@@ -206,310 +209,6 @@ struct Custom {
    error: Box<dyn error::Error + Send + Sync>,
 }

-/// A list specifying general categories of I/O error.
-///
-/// This list is intended to grow over time and it is not recommended to
-/// exhaustively match against it.
-///
-/// # Handling errors and matching on `ErrorKind`
-///
-/// In application code, use `match` for the `ErrorKind` values you are
-/// expecting; use `_` to match "all other errors".
-///
-/// In comprehensive and thorough tests that want to verify that a test doesn't
-/// return any known incorrect error kind, you may want to cut-and-paste the
-/// current full list of errors from here into your test code, and then match
-/// `_` as the correct case. This seems counterintuitive, but it will make your
-/// tests more robust. In particular, if you want to verify that your code does
-/// produce an unrecognized error kind, the robust solution is to check for all
-/// the recognized error kinds and fail in those cases.
-#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
-#[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(test), rustc_diagnostic_item = "io_errorkind")]
-#[allow(deprecated)]
-#[non_exhaustive]
-pub enum ErrorKind {
-    /// An entity was not found, often a file.
-    #[stable(feature = "rust1", since = "1.0.0")]
-    NotFound,
-    /// The operation lacked the necessary privileges to complete.
-    #[stable(feature = "rust1", since = "1.0.0")]
-    PermissionDenied,
-    /// The connection was refused by the remote server.
-    #[stable(feature = "rust1", since = "1.0.0")]
-    ConnectionRefused,
-    /// The connection was reset by the remote server.
-    #[stable(feature = "rust1", since = "1.0.0")]
-    ConnectionReset,
-    /// The remote host is not reachable.
-    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
-    HostUnreachable,
-    /// The network containing the remote host is not reachable.
-    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
-    NetworkUnreachable,
-    /// The connection was aborted (terminated) by the remote server.
-    #[stable(feature = "rust1", since = "1.0.0")]
-    ConnectionAborted,
-    /// The network operation failed because it was not connected yet.
-    #[stable(feature = "rust1", since = "1.0.0")]
-    NotConnected,
-    /// A socket address could not be bound because the address is already in
-    /// use elsewhere.
-    #[stable(feature = "rust1", since = "1.0.0")]
-    AddrInUse,
-    /// A nonexistent interface was requested or the requested address was not
-    /// local.
-    #[stable(feature = "rust1", since = "1.0.0")]
-    AddrNotAvailable,
-    /// The system's networking is down.
-    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
-    NetworkDown,
-    /// The operation failed because a pipe was closed.
-    #[stable(feature = "rust1", since = "1.0.0")]
-    BrokenPipe,
-    /// An entity already exists, often a file.
-    #[stable(feature = "rust1", since = "1.0.0")]
-    AlreadyExists,
-    /// The operation needs to block to complete, but the blocking operation was
-    /// requested to not occur.
-    #[stable(feature = "rust1", since = "1.0.0")]
-    WouldBlock,
-    /// A filesystem object is, unexpectedly, not a directory.
-    ///
-    /// For example, a filesystem path was specified where one of the intermediate directory
-    /// components was, in fact, a plain file.
-    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
-    NotADirectory,
-    /// The filesystem object is, unexpectedly, a directory.
-    ///
-    /// A directory was specified when a non-directory was expected.
-    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
-    IsADirectory,
-    /// A non-empty directory was specified where an empty directory was expected.
-    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
-    DirectoryNotEmpty,
-    /// The filesystem or storage medium is read-only, but a write operation was attempted.
-    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
-    ReadOnlyFilesystem,
-    /// Loop in the filesystem or IO subsystem; often, too many levels of symbolic links.
-    ///
-    /// There was a loop (or excessively long chain) resolving a filesystem object
-    /// or file IO object.
-    ///
-    /// On Unix this is usually the result of a symbolic link loop; or, of exceeding the
-    /// system-specific limit on the depth of symlink traversal.
-    #[unstable(feature = "io_error_more", issue = "86442")]
-    FilesystemLoop,
-    /// Stale network file handle.
-    ///
-    /// With some network filesystems, notably NFS, an open file (or directory) can be invalidated
-    /// by problems with the network or server.
-    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
-    StaleNetworkFileHandle,
-    /// A parameter was incorrect.
-    #[stable(feature = "rust1", since = "1.0.0")]
-    InvalidInput,
-    /// Data not valid for the operation were encountered.
-    ///
-    /// Unlike [`InvalidInput`], this typically means that the operation
-    /// parameters were valid, however the error was caused by malformed
-    /// input data.
-    ///
-    /// For example, a function that reads a file into a string will error with
-    /// `InvalidData` if the file's contents are not valid UTF-8.
-    ///
-    /// [`InvalidInput`]: ErrorKind::InvalidInput
-    #[stable(feature = "io_invalid_data", since = "1.2.0")]
-    InvalidData,
-    /// The I/O operation's timeout expired, causing it to be canceled.
-    #[stable(feature = "rust1", since = "1.0.0")]
-    TimedOut,
-    /// An error returned when an operation could not be completed because a
-    /// call to an underlying writer returned [`Ok(0)`].
-    ///
-    /// This typically means that an operation could only succeed if it wrote a
-    /// particular number of bytes but only a smaller number of bytes could be
-    /// written.
-    ///
-    /// [`Ok(0)`]: Ok
-    #[stable(feature = "rust1", since = "1.0.0")]
-    WriteZero,
-    /// The underlying storage (typically, a filesystem) is full.
-    ///
-    /// This does not include out of quota errors.
-    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
-    StorageFull,
-    /// Seek on unseekable file.
-    ///
-    /// Seeking was attempted on an open file handle which is not suitable for seeking - for
-    /// example, on Unix, a named pipe opened with `File::open`.
-    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
-    NotSeekable,
-    /// Filesystem quota or some other kind of quota was exceeded.
-    #[stable(feature = "io_error_quota_exceeded", since = "1.85.0")]
-    QuotaExceeded,
-    /// File larger than allowed or supported.
-    ///
-    /// This might arise from a hard limit of the underlying filesystem or file access API, or from
-    /// an administratively imposed resource limitation.  Simple disk full, and out of quota, have
-    /// their own errors.
-    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
-    FileTooLarge,
-    /// Resource is busy.
-    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
-    ResourceBusy,
-    /// Executable file is busy.
-    ///
-    /// An attempt was made to write to a file which is also in use as a running program.  (Not all
-    /// operating systems detect this situation.)
-    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
-    ExecutableFileBusy,
-    /// Deadlock (avoided).
-    ///
-    /// A file locking operation would result in deadlock.  This situation is typically detected, if
-    /// at all, on a best-effort basis.
-    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
-    Deadlock,
-    /// Cross-device or cross-filesystem (hard) link or rename.
-    #[stable(feature = "io_error_crosses_devices", since = "1.85.0")]
-    CrossesDevices,
-    /// Too many (hard) links to the same filesystem object.
-    ///
-    /// The filesystem does not support making so many hardlinks to the same file.
-    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
-    TooManyLinks,
-    /// A filename was invalid.
-    ///
-    /// This error can also occur if a length limit for a name was exceeded.
-    #[stable(feature = "io_error_invalid_filename", since = "1.87.0")]
-    InvalidFilename,
-    /// Program argument list too long.
-    ///
-    /// When trying to run an external program, a system or process limit on the size of the
-    /// arguments would have been exceeded.
-    #[stable(feature = "io_error_a_bit_more", since = "1.83.0")]
-    ArgumentListTooLong,
-    /// This operation was interrupted.
-    ///
-    /// Interrupted operations can typically be retried.
-    #[stable(feature = "rust1", since = "1.0.0")]
-    Interrupted,
-
-    /// This operation is unsupported on this platform.
-    ///
-    /// This means that the operation can never succeed.
-    #[stable(feature = "unsupported_error", since = "1.53.0")]
-    Unsupported,
-
-    // ErrorKinds which are primarily categorisations for OS error
-    // codes should be added above.
-    //
-    /// An error returned when an operation could not be completed because an
-    /// "end of file" was reached prematurely.
-    ///
-    /// This typically means that an operation could only succeed if it read a
-    /// particular number of bytes but only a smaller number of bytes could be
-    /// read.
-    #[stable(feature = "read_exact", since = "1.6.0")]
-    UnexpectedEof,
-
-    /// An operation could not be completed, because it failed
-    /// to allocate enough memory.
-    #[stable(feature = "out_of_memory_error", since = "1.54.0")]
-    OutOfMemory,
-
-    /// The operation was partially successful and needs to be checked
-    /// later on due to not blocking.
-    #[unstable(feature = "io_error_inprogress", issue = "130840")]
-    InProgress,
-
-    // "Unusual" error kinds which do not correspond simply to (sets
-    // of) OS error codes, should be added just above this comment.
-    // `Other` and `Uncategorized` should remain at the end:
-    //
-    /// A custom error that does not fall under any other I/O error kind.
-    ///
-    /// This can be used to construct your own errors that do not match any
-    /// [`ErrorKind`].
-    ///
-    /// This [`ErrorKind`] is not used by the standard library.
-    ///
-    /// Errors from the standard library that do not fall under any of the I/O
-    /// error kinds cannot be `match`ed on, and will only match a wildcard (`_`) pattern.
-    /// New [`ErrorKind`]s might be added in the future for some of those.
-    #[stable(feature = "rust1", since = "1.0.0")]
-    Other,
-
-    /// Any I/O error from the standard library that's not part of this list.
-    ///
-    /// Errors that are `Uncategorized` now may move to a different or a new
-    /// [`ErrorKind`] variant in the future. It is not recommended to match
-    /// an error against `Uncategorized`; use a wildcard match (`_`) instead.
-    #[unstable(feature = "io_error_uncategorized", issue = "none")]
-    #[doc(hidden)]
-    Uncategorized,
-}
-
-impl ErrorKind {
-    pub(crate) fn as_str(&self) -> &'static str {
-        use ErrorKind::*;
-        match *self {
-            // tidy-alphabetical-start
-            AddrInUse => "address in use",
-            AddrNotAvailable => "address not available",
-            AlreadyExists => "entity already exists",
-            ArgumentListTooLong => "argument list too long",
-            BrokenPipe => "broken pipe",
-            ConnectionAborted => "connection aborted",
-            ConnectionRefused => "connection refused",
-            ConnectionReset => "connection reset",
-            CrossesDevices => "cross-device link or rename",
-            Deadlock => "deadlock",
-            DirectoryNotEmpty => "directory not empty",
-            ExecutableFileBusy => "executable file busy",
-            FileTooLarge => "file too large",
-            FilesystemLoop => "filesystem loop or indirection limit (e.g. symlink loop)",
-            HostUnreachable => "host unreachable",
-            InProgress => "in progress",
-            Interrupted => "operation interrupted",
-            InvalidData => "invalid data",
-            InvalidFilename => "invalid filename",
-            InvalidInput => "invalid input parameter",
-            IsADirectory => "is a directory",
-            NetworkDown => "network down",
-            NetworkUnreachable => "network unreachable",
-            NotADirectory => "not a directory",
-            NotConnected => "not connected",
-            NotFound => "entity not found",
-            NotSeekable => "seek on unseekable file",
-            Other => "other error",
-            OutOfMemory => "out of memory",
-            PermissionDenied => "permission denied",
-            QuotaExceeded => "quota exceeded",
-            ReadOnlyFilesystem => "read-only filesystem or storage medium",
-            ResourceBusy => "resource busy",
-            StaleNetworkFileHandle => "stale network file handle",
-            StorageFull => "no storage space",
-            TimedOut => "timed out",
-            TooManyLinks => "too many links",
-            Uncategorized => "uncategorized error",
-            UnexpectedEof => "unexpected end of file",
-            Unsupported => "unsupported",
-            WouldBlock => "operation would block",
-            WriteZero => "write zero",
-            // tidy-alphabetical-end
-        }
-    }
-}
-
-#[stable(feature = "io_errorkind_display", since = "1.60.0")]
-impl fmt::Display for ErrorKind {
-    /// Shows a human-readable description of the `ErrorKind`.
-    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt.write_str(self.as_str())
-    }
-}
-
 /// Intended for use for errors not exposed to the user, where allocating onto
 /// the heap (for normal construction via Error::new) is too costly.
 #[stable(feature = "io_error_from_errorkind", since = "1.14.0")]
@@ -283,77 +283,6 @@ unsafe fn decode_repr<C, F>(ptr: NonNull<()>, make_custom: F) -> ErrorData<C>
    }
 }

-impl ErrorKind {
-    // This compiles to the same code as the check+transmute, but doesn't require
-    // unsafe, or to hard-code max ErrorKind or its size in a way the compiler
-    // couldn't verify.
-    #[inline]
-    #[unstable(
-        feature = "core_io_internals",
-        reason = "exposed only for libstd",
-        issue = "none"
-    )]
-    #[doc(hidden)]
-    pub const fn from_prim(ek: u32) -> Option<Self> {
-        macro_rules! from_prim {
-            ($prim:expr => $Enum:ident { $($Variant:ident),* $(,)? }) => {{
-                // Force a compile error if the list gets out of date.
-                const _: fn(e: $Enum) = |e: $Enum| match e {
-                    $($Enum::$Variant => (),)*
-                };
-                match $prim {
-                    $(v if v == ($Enum::$Variant as _) => Some($Enum::$Variant),)*
-                    _ => None,
-                }
-            }}
-        }
-        from_prim!(ek => ErrorKind {
-            NotFound,
-            PermissionDenied,
-            ConnectionRefused,
-            ConnectionReset,
-            HostUnreachable,
-            NetworkUnreachable,
-            ConnectionAborted,
-            NotConnected,
-            AddrInUse,
-            AddrNotAvailable,
-            NetworkDown,
-            BrokenPipe,
-            AlreadyExists,
-            WouldBlock,
-            NotADirectory,
-            IsADirectory,
-            DirectoryNotEmpty,
-            ReadOnlyFilesystem,
-            FilesystemLoop,
-            StaleNetworkFileHandle,
-            InvalidInput,
-            InvalidData,
-            TimedOut,
-            WriteZero,
-            StorageFull,
-            NotSeekable,
-            QuotaExceeded,
-            FileTooLarge,
-            ResourceBusy,
-            ExecutableFileBusy,
-            Deadlock,
-            CrossesDevices,
-            TooManyLinks,
-            InvalidFilename,
-            ArgumentListTooLong,
-            Interrupted,
-            Other,
-            UnexpectedEof,
-            Unsupported,
-            OutOfMemory,
-            InProgress,
-            Uncategorized,
-        })
-    }
-}
-
 // Some static checking to alert us if a change breaks any of the assumptions
 // that our encoding relies on for correctness and soundness. (Some of these are
 // a bit overly thorough/cautious, admittedly)
@@ -321,7 +321,9 @@
 #![feature(const_default)]
 #![feature(core_float_math)]
 #![feature(core_intrinsics)]
+#![feature(core_io)]
 #![feature(core_io_borrowed_buf)]
+#![feature(core_io_internals)]
 #![feature(cstr_display)]
 #![feature(drop_guard)]
 #![feature(duration_constants)]
@@ -1,6 +1,6 @@
 //@ has deprecated/struct.A.html '//a[@href="{{channel}}/core/ops/range/struct.Range.html#structfield.start"]' 'start'
-//@ has deprecated/struct.B1.html '//a[@href="{{channel}}/std/io/error/enum.ErrorKind.html#variant.NotFound"]' 'not_found'
-//@ has deprecated/struct.B2.html '//a[@href="{{channel}}/std/io/error/enum.ErrorKind.html#variant.NotFound"]' 'not_found'
+//@ has deprecated/struct.B1.html '//a[@href="{{channel}}/core/io/error/enum.ErrorKind.html#variant.NotFound"]' 'not_found'
+//@ has deprecated/struct.B2.html '//a[@href="{{channel}}/core/io/error/enum.ErrorKind.html#variant.NotFound"]' 'not_found'

 #[deprecated = "[start][std::ops::Range::start]"]
 pub struct A;
@@ -1,9 +1,9 @@
 //@ has field/index.html '//a[@href="{{channel}}/core/ops/range/struct.Range.html#structfield.start"]' 'start'
-//@ has field/index.html '//a[@href="{{channel}}/std/io/error/enum.ErrorKind.html#variant.NotFound"]' 'not_found'
+//@ has field/index.html '//a[@href="{{channel}}/core/io/error/enum.ErrorKind.html#variant.NotFound"]' 'not_found'
 //@ has field/index.html '//a[@href="struct.FieldAndMethod.html#structfield.x"]' 'x'
 //@ has field/index.html '//a[@href="enum.VariantAndMethod.html#variant.X"]' 'X'
 //! [start][std::ops::Range::start]
-//! [not_found][std::io::ErrorKind::NotFound]
+//! [not_found][core::io::ErrorKind::NotFound]
 //! [x][field@crate::FieldAndMethod::x]
 //! [X][variant@crate::VariantAndMethod::X]

@@ -0,0 +1,12 @@
+// Ensure `ErrorKind` from `core` is gated behind `core_io`
+//@ edition:2024
+
+use std::io::ErrorKind as ErrorKindFromStd;
+
+use core::io::ErrorKind as ErrorKindFromCore;
+//~^ ERROR use of unstable library feature `core_io`
+
+// Asserting both ErrorKinds are the same.
+const _: [ErrorKindFromCore; 1] = [ErrorKindFromStd::Other];
+
+fn main() {}
@@ -0,0 +1,13 @@
+error[E0658]: use of unstable library feature `core_io`
+  --> $DIR/feature-gate-io_error_kind_in_core.rs:6:5
+   |
+LL | use core::io::ErrorKind as ErrorKindFromCore;
+   |     ^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #154046 <https://github.com/rust-lang/rust/issues/154046> for more information
+   = help: add `#![feature(core_io)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0658`.