From 229c00415fbaeb511208ed8f9e22516e6c084233 Mon Sep 17 00:00:00 2001
From: Mara Bos <m-ou.se@m-ou.se>
Date: Wed, 20 Jan 2021 18:19:50 +0100
Subject: [PATCH] Seal all filesystem related extension traits.

---
 library/std/src/fs.rs                 | 28 +++++++++++++++++++++++++++
 library/std/src/os/android/fs.rs      |  3 ++-
 library/std/src/os/dragonfly/fs.rs    |  3 ++-
 library/std/src/os/emscripten/fs.rs   |  3 ++-
 library/std/src/os/freebsd/fs.rs      |  3 ++-
 library/std/src/os/fuchsia/fs.rs      |  3 ++-
 library/std/src/os/haiku/fs.rs        |  3 ++-
 library/std/src/os/illumos/fs.rs      |  3 ++-
 library/std/src/os/ios/fs.rs          |  3 ++-
 library/std/src/os/linux/fs.rs        |  3 ++-
 library/std/src/os/macos/fs.rs        |  3 ++-
 library/std/src/os/netbsd/fs.rs       |  3 ++-
 library/std/src/os/openbsd/fs.rs      |  3 ++-
 library/std/src/os/redox/fs.rs        |  3 ++-
 library/std/src/os/solaris/fs.rs      |  3 ++-
 library/std/src/os/vxworks/fs.rs      |  3 ++-
 library/std/src/sys/unix/ext/fs.rs    | 15 +++++++-------
 library/std/src/sys/wasi/ext/fs.rs    | 11 ++++++-----
 library/std/src/sys/windows/ext/fs.rs |  9 +++++----
 19 files changed, 77 insertions(+), 31 deletions(-)

diff --git a/library/std/src/fs.rs b/library/std/src/fs.rs
index e2d4f2e6a56af..6152f2d458115 100644
--- a/library/std/src/fs.rs
+++ b/library/std/src/fs.rs
@@ -92,6 +92,10 @@ pub struct File {
     inner: fs_imp::File,
 }
 
+/// Allows extension traits within `std`.
+#[unstable(feature = "sealed", issue = "none")]
+impl crate::sealed::Sealed for File {}
+
 /// Metadata information about a file.
 ///
 /// This structure is returned from the [`metadata`] or
@@ -102,6 +106,10 @@ pub struct File {
 #[derive(Clone)]
 pub struct Metadata(fs_imp::FileAttr);
 
+/// Allows extension traits within `std`.
+#[unstable(feature = "sealed", issue = "none")]
+impl crate::sealed::Sealed for Metadata {}
+
 /// Iterator over the entries in a directory.
 ///
 /// This iterator is returned from the [`read_dir`] function of this module and
@@ -128,6 +136,10 @@ pub struct ReadDir(fs_imp::ReadDir);
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct DirEntry(fs_imp::DirEntry);
 
+/// Allows extension traits within `std`.
+#[unstable(feature = "sealed", issue = "none")]
+impl crate::sealed::Sealed for DirEntry {}
+
 /// Options and flags which can be used to configure how a file is opened.
 ///
 /// This builder exposes the ability to configure how a [`File`] is opened and
@@ -167,6 +179,10 @@ pub struct DirEntry(fs_imp::DirEntry);
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct OpenOptions(fs_imp::OpenOptions);
 
+/// Allows extension traits within `std`.
+#[unstable(feature = "sealed", issue = "none")]
+impl crate::sealed::Sealed for OpenOptions {}
+
 /// Representation of the various permissions on a file.
 ///
 /// This module only currently provides one bit of information,
@@ -179,12 +195,20 @@ pub struct OpenOptions(fs_imp::OpenOptions);
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Permissions(fs_imp::FilePermissions);
 
+/// Allows extension traits within `std`.
+#[unstable(feature = "sealed", issue = "none")]
+impl crate::sealed::Sealed for Permissions {}
+
 /// A structure representing a type of file with accessors for each file type.
 /// It is returned by [`Metadata::file_type`] method.
 #[stable(feature = "file_type", since = "1.1.0")]
 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
 pub struct FileType(fs_imp::FileType);
 
+/// Allows extension traits within `std`.
+#[unstable(feature = "sealed", issue = "none")]
+impl crate::sealed::Sealed for FileType {}
+
 /// A builder used to create directories in various manners.
 ///
 /// This builder also supports platform-specific options.
@@ -195,6 +219,10 @@ pub struct DirBuilder {
     recursive: bool,
 }
 
+/// Allows extension traits within `std`.
+#[unstable(feature = "sealed", issue = "none")]
+impl crate::sealed::Sealed for DirBuilder {}
+
 /// Indicates how large a buffer to pre-allocate before reading the entire file.
 fn initial_buffer_size(file: &File) -> usize {
     // Allocate one extra byte so the buffer doesn't need to grow before the
diff --git a/library/std/src/os/android/fs.rs b/library/std/src/os/android/fs.rs
index 6aeef330dfa24..82fe0b90c31c8 100644
--- a/library/std/src/os/android/fs.rs
+++ b/library/std/src/os/android/fs.rs
@@ -1,6 +1,7 @@
 #![stable(feature = "metadata_ext", since = "1.1.0")]
 
 use crate::fs::Metadata;
+use crate::sealed::Sealed;
 use crate::sys_common::AsInner;
 
 #[allow(deprecated)]
@@ -10,7 +11,7 @@ use crate::os::android::raw;
 ///
 /// [`fs::Metadata`]: crate::fs::Metadata
 #[stable(feature = "metadata_ext", since = "1.1.0")]
-pub trait MetadataExt {
+pub trait MetadataExt: Sealed {
     /// Gain a reference to the underlying `stat` structure which contains
     /// the raw information returned by the OS.
     ///
diff --git a/library/std/src/os/dragonfly/fs.rs b/library/std/src/os/dragonfly/fs.rs
index e4c4e04cd30aa..e885784739cac 100644
--- a/library/std/src/os/dragonfly/fs.rs
+++ b/library/std/src/os/dragonfly/fs.rs
@@ -1,6 +1,7 @@
 #![stable(feature = "metadata_ext", since = "1.1.0")]
 
 use crate::fs::Metadata;
+use crate::sealed::Sealed;
 use crate::sys_common::AsInner;
 
 #[allow(deprecated)]
@@ -10,7 +11,7 @@ use crate::os::dragonfly::raw;
 ///
 /// [`fs::Metadata`]: crate::fs::Metadata
 #[stable(feature = "metadata_ext", since = "1.1.0")]
-pub trait MetadataExt {
+pub trait MetadataExt: Sealed {
     /// Gain a reference to the underlying `stat` structure which contains
     /// the raw information returned by the OS.
     ///
diff --git a/library/std/src/os/emscripten/fs.rs b/library/std/src/os/emscripten/fs.rs
index d4f758a3457fe..a9f46de4d2ec0 100644
--- a/library/std/src/os/emscripten/fs.rs
+++ b/library/std/src/os/emscripten/fs.rs
@@ -1,6 +1,7 @@
 #![stable(feature = "metadata_ext", since = "1.1.0")]
 
 use crate::fs::Metadata;
+use crate::sealed::Sealed;
 use crate::sys_common::AsInner;
 
 #[allow(deprecated)]
@@ -10,7 +11,7 @@ use crate::os::emscripten::raw;
 ///
 /// [`fs::Metadata`]: crate::fs::Metadata
 #[stable(feature = "metadata_ext", since = "1.1.0")]
-pub trait MetadataExt {
+pub trait MetadataExt: Sealed {
     /// Gain a reference to the underlying `stat` structure which contains
     /// the raw information returned by the OS.
     ///
diff --git a/library/std/src/os/freebsd/fs.rs b/library/std/src/os/freebsd/fs.rs
index 1eda8690d5d1b..0db3970d18a6a 100644
--- a/library/std/src/os/freebsd/fs.rs
+++ b/library/std/src/os/freebsd/fs.rs
@@ -1,6 +1,7 @@
 #![stable(feature = "metadata_ext", since = "1.1.0")]
 
 use crate::fs::Metadata;
+use crate::sealed::Sealed;
 use crate::sys_common::AsInner;
 
 #[allow(deprecated)]
@@ -10,7 +11,7 @@ use crate::os::freebsd::raw;
 ///
 /// [`fs::Metadata`]: crate::fs::Metadata
 #[stable(feature = "metadata_ext", since = "1.1.0")]
-pub trait MetadataExt {
+pub trait MetadataExt: Sealed {
     /// Gain a reference to the underlying `stat` structure which contains
     /// the raw information returned by the OS.
     ///
diff --git a/library/std/src/os/fuchsia/fs.rs b/library/std/src/os/fuchsia/fs.rs
index b48a46f9124a9..a2da22f6cec3f 100644
--- a/library/std/src/os/fuchsia/fs.rs
+++ b/library/std/src/os/fuchsia/fs.rs
@@ -1,13 +1,14 @@
 #![stable(feature = "metadata_ext", since = "1.1.0")]
 
 use crate::fs::Metadata;
+use crate::sealed::Sealed;
 use crate::sys_common::AsInner;
 
 /// OS-specific extensions to [`fs::Metadata`].
 ///
 /// [`fs::Metadata`]: crate::fs::Metadata
 #[stable(feature = "metadata_ext", since = "1.1.0")]
-pub trait MetadataExt {
+pub trait MetadataExt: Sealed {
     #[stable(feature = "metadata_ext2", since = "1.8.0")]
     fn st_dev(&self) -> u64;
     #[stable(feature = "metadata_ext2", since = "1.8.0")]
diff --git a/library/std/src/os/haiku/fs.rs b/library/std/src/os/haiku/fs.rs
index 28015f6252633..9fb47d76da97a 100644
--- a/library/std/src/os/haiku/fs.rs
+++ b/library/std/src/os/haiku/fs.rs
@@ -1,6 +1,7 @@
 #![stable(feature = "metadata_ext", since = "1.1.0")]
 
 use crate::fs::Metadata;
+use crate::sealed::Sealed;
 use crate::sys_common::AsInner;
 
 #[allow(deprecated)]
@@ -10,7 +11,7 @@ use crate::os::haiku::raw;
 ///
 /// [`fs::Metadata`]: crate::fs::Metadata
 #[stable(feature = "metadata_ext", since = "1.1.0")]
-pub trait MetadataExt {
+pub trait MetadataExt: Sealed {
     /// Gain a reference to the underlying `stat` structure which contains
     /// the raw information returned by the OS.
     ///
diff --git a/library/std/src/os/illumos/fs.rs b/library/std/src/os/illumos/fs.rs
index 021d154ff5a8a..d2c5cab5d3e01 100644
--- a/library/std/src/os/illumos/fs.rs
+++ b/library/std/src/os/illumos/fs.rs
@@ -1,6 +1,7 @@
 #![stable(feature = "metadata_ext", since = "1.1.0")]
 
 use crate::fs::Metadata;
+use crate::sealed::Sealed;
 use crate::sys_common::AsInner;
 
 #[allow(deprecated)]
@@ -10,7 +11,7 @@ use crate::os::illumos::raw;
 ///
 /// [`fs::Metadata`]: crate::fs::Metadata
 #[stable(feature = "metadata_ext", since = "1.1.0")]
-pub trait MetadataExt {
+pub trait MetadataExt: Sealed {
     /// Gain a reference to the underlying `stat` structure which contains
     /// the raw information returned by the OS.
     ///
diff --git a/library/std/src/os/ios/fs.rs b/library/std/src/os/ios/fs.rs
index 2c5e38a803d30..f8769e36cb7cc 100644
--- a/library/std/src/os/ios/fs.rs
+++ b/library/std/src/os/ios/fs.rs
@@ -1,6 +1,7 @@
 #![stable(feature = "metadata_ext", since = "1.1.0")]
 
 use crate::fs::Metadata;
+use crate::sealed::Sealed;
 use crate::sys_common::AsInner;
 
 #[allow(deprecated)]
@@ -10,7 +11,7 @@ use crate::os::ios::raw;
 ///
 /// [`fs::Metadata`]: crate::fs::Metadata
 #[stable(feature = "metadata_ext", since = "1.1.0")]
-pub trait MetadataExt {
+pub trait MetadataExt: Sealed {
     /// Gain a reference to the underlying `stat` structure which contains
     /// the raw information returned by the OS.
     ///
diff --git a/library/std/src/os/linux/fs.rs b/library/std/src/os/linux/fs.rs
index 9b7af97616c9d..69c0f80bd12c4 100644
--- a/library/std/src/os/linux/fs.rs
+++ b/library/std/src/os/linux/fs.rs
@@ -3,6 +3,7 @@
 #![stable(feature = "metadata_ext", since = "1.1.0")]
 
 use crate::fs::Metadata;
+use crate::sealed::Sealed;
 use crate::sys_common::AsInner;
 
 #[allow(deprecated)]
@@ -12,7 +13,7 @@ use crate::os::linux::raw;
 ///
 /// [`fs::Metadata`]: crate::fs::Metadata
 #[stable(feature = "metadata_ext", since = "1.1.0")]
-pub trait MetadataExt {
+pub trait MetadataExt: Sealed {
     /// Gain a reference to the underlying `stat` structure which contains
     /// the raw information returned by the OS.
     ///
diff --git a/library/std/src/os/macos/fs.rs b/library/std/src/os/macos/fs.rs
index 4152c3529361d..00f94e5ef99a0 100644
--- a/library/std/src/os/macos/fs.rs
+++ b/library/std/src/os/macos/fs.rs
@@ -1,6 +1,7 @@
 #![stable(feature = "metadata_ext", since = "1.1.0")]
 
 use crate::fs::Metadata;
+use crate::sealed::Sealed;
 use crate::sys_common::AsInner;
 
 #[allow(deprecated)]
@@ -10,7 +11,7 @@ use crate::os::macos::raw;
 ///
 /// [`fs::Metadata`]: crate::fs::Metadata
 #[stable(feature = "metadata_ext", since = "1.1.0")]
-pub trait MetadataExt {
+pub trait MetadataExt: Sealed {
     /// Gain a reference to the underlying `stat` structure which contains
     /// the raw information returned by the OS.
     ///
diff --git a/library/std/src/os/netbsd/fs.rs b/library/std/src/os/netbsd/fs.rs
index 6b29a40d2b545..c4952519baee7 100644
--- a/library/std/src/os/netbsd/fs.rs
+++ b/library/std/src/os/netbsd/fs.rs
@@ -1,6 +1,7 @@
 #![stable(feature = "metadata_ext", since = "1.1.0")]
 
 use crate::fs::Metadata;
+use crate::sealed::Sealed;
 use crate::sys_common::AsInner;
 
 #[allow(deprecated)]
@@ -10,7 +11,7 @@ use crate::os::netbsd::raw;
 ///
 /// [`fs::Metadata`]: crate::fs::Metadata
 #[stable(feature = "metadata_ext", since = "1.1.0")]
-pub trait MetadataExt {
+pub trait MetadataExt: Sealed {
     /// Gain a reference to the underlying `stat` structure which contains
     /// the raw information returned by the OS.
     ///
diff --git a/library/std/src/os/openbsd/fs.rs b/library/std/src/os/openbsd/fs.rs
index 3143dc95fdf44..f919787f7625f 100644
--- a/library/std/src/os/openbsd/fs.rs
+++ b/library/std/src/os/openbsd/fs.rs
@@ -1,6 +1,7 @@
 #![stable(feature = "metadata_ext", since = "1.1.0")]
 
 use crate::fs::Metadata;
+use crate::sealed::Sealed;
 use crate::sys_common::AsInner;
 
 #[allow(deprecated)]
@@ -10,7 +11,7 @@ use crate::os::openbsd::raw;
 ///
 /// [`fs::Metadata`]: crate::fs::Metadata
 #[stable(feature = "metadata_ext", since = "1.1.0")]
-pub trait MetadataExt {
+pub trait MetadataExt: Sealed {
     /// Gain a reference to the underlying `stat` structure which contains
     /// the raw information returned by the OS.
     ///
diff --git a/library/std/src/os/redox/fs.rs b/library/std/src/os/redox/fs.rs
index 0f179c8b837dd..e7eb142fc667c 100644
--- a/library/std/src/os/redox/fs.rs
+++ b/library/std/src/os/redox/fs.rs
@@ -1,6 +1,7 @@
 #![stable(feature = "metadata_ext", since = "1.1.0")]
 
 use crate::fs::Metadata;
+use crate::sealed::Sealed;
 use crate::sys_common::AsInner;
 
 #[allow(deprecated)]
@@ -10,7 +11,7 @@ use crate::os::redox::raw;
 ///
 /// [`fs::Metadata`]: crate::fs::Metadata
 #[stable(feature = "metadata_ext", since = "1.1.0")]
-pub trait MetadataExt {
+pub trait MetadataExt: Sealed {
     /// Gain a reference to the underlying `stat` structure which contains
     /// the raw information returned by the OS.
     ///
diff --git a/library/std/src/os/solaris/fs.rs b/library/std/src/os/solaris/fs.rs
index 908c5c38a842e..6594a567f4c43 100644
--- a/library/std/src/os/solaris/fs.rs
+++ b/library/std/src/os/solaris/fs.rs
@@ -1,6 +1,7 @@
 #![stable(feature = "metadata_ext", since = "1.1.0")]
 
 use crate::fs::Metadata;
+use crate::sealed::Sealed;
 use crate::sys_common::AsInner;
 
 #[allow(deprecated)]
@@ -10,7 +11,7 @@ use crate::os::solaris::raw;
 ///
 /// [`fs::Metadata`]: crate::fs::Metadata
 #[stable(feature = "metadata_ext", since = "1.1.0")]
-pub trait MetadataExt {
+pub trait MetadataExt: Sealed {
     /// Gain a reference to the underlying `stat` structure which contains
     /// the raw information returned by the OS.
     ///
diff --git a/library/std/src/os/vxworks/fs.rs b/library/std/src/os/vxworks/fs.rs
index 77e6238ca1f52..02653045a1986 100644
--- a/library/std/src/os/vxworks/fs.rs
+++ b/library/std/src/os/vxworks/fs.rs
@@ -1,12 +1,13 @@
 #![stable(feature = "metadata_ext", since = "1.1.0")]
 
 use crate::fs::Metadata;
+use crate::sealed::Sealed;
 use crate::sys_common::AsInner;
 
 ///
 /// [`fs::Metadata`]: crate::fs::Metadata
 #[stable(feature = "metadata_ext", since = "1.1.0")]
-pub trait MetadataExt {
+pub trait MetadataExt: Sealed {
     #[stable(feature = "metadata_ext2", since = "1.8.0")]
     fn st_dev(&self) -> u64;
     #[stable(feature = "metadata_ext2", since = "1.8.0")]
diff --git a/library/std/src/sys/unix/ext/fs.rs b/library/std/src/sys/unix/ext/fs.rs
index ba75b9bac8035..4940f014d9dab 100644
--- a/library/std/src/sys/unix/ext/fs.rs
+++ b/library/std/src/sys/unix/ext/fs.rs
@@ -5,6 +5,7 @@
 use crate::fs::{self, OpenOptions, Permissions};
 use crate::io;
 use crate::path::Path;
+use crate::sealed::Sealed;
 use crate::sys;
 use crate::sys::platform::fs::MetadataExt as UnixMetadataExt;
 use crate::sys_common::{AsInner, AsInnerMut, FromInner};
@@ -14,7 +15,7 @@ use io::{Read, Write};
 
 /// Unix-specific extensions to [`fs::File`].
 #[stable(feature = "file_offset", since = "1.15.0")]
-pub trait FileExt {
+pub trait FileExt: Sealed {
     /// Reads a number of bytes starting from a given offset.
     ///
     /// Returns the number of bytes read.
@@ -220,7 +221,7 @@ impl FileExt for fs::File {
 
 /// Unix-specific extensions to [`fs::Permissions`].
 #[stable(feature = "fs_ext", since = "1.1.0")]
-pub trait PermissionsExt {
+pub trait PermissionsExt: Sealed {
     /// Returns the underlying raw `st_mode` bits that contain the standard
     /// Unix permissions for this file.
     ///
@@ -297,7 +298,7 @@ impl PermissionsExt for Permissions {
 
 /// Unix-specific extensions to [`fs::OpenOptions`].
 #[stable(feature = "fs_ext", since = "1.1.0")]
-pub trait OpenOptionsExt {
+pub trait OpenOptionsExt: Sealed {
     /// Sets the mode bits that a new file will be created with.
     ///
     /// If a new file is created as part of an `OpenOptions::open` call then this
@@ -365,7 +366,7 @@ impl OpenOptionsExt for OpenOptions {
 
 /// Unix-specific extensions to [`fs::Metadata`].
 #[stable(feature = "metadata_ext", since = "1.1.0")]
-pub trait MetadataExt {
+pub trait MetadataExt: Sealed {
     /// Returns the ID of the device containing the file.
     ///
     /// # Examples
@@ -716,7 +717,7 @@ impl MetadataExt for fs::Metadata {
 /// Adds support for special Unix file types such as block/character devices,
 /// pipes, and sockets.
 #[stable(feature = "file_type_ext", since = "1.5.0")]
-pub trait FileTypeExt {
+pub trait FileTypeExt: Sealed {
     /// Returns `true` if this file type is a block device.
     ///
     /// # Examples
@@ -809,7 +810,7 @@ impl FileTypeExt for fs::FileType {
 
 /// Unix-specific extension methods for [`fs::DirEntry`].
 #[stable(feature = "dir_entry_ext", since = "1.1.0")]
-pub trait DirEntryExt {
+pub trait DirEntryExt: Sealed {
     /// Returns the underlying `d_ino` field in the contained `dirent`
     /// structure.
     ///
@@ -860,7 +861,7 @@ pub fn symlink<P: AsRef<Path>, Q: AsRef<Path>>(original: P, link: Q) -> io::Resu
 
 /// Unix-specific extensions to [`fs::DirBuilder`].
 #[stable(feature = "dir_builder", since = "1.6.0")]
-pub trait DirBuilderExt {
+pub trait DirBuilderExt: Sealed {
     /// Sets the mode to create new directories with. This option defaults to
     /// 0o777.
     ///
diff --git a/library/std/src/sys/wasi/ext/fs.rs b/library/std/src/sys/wasi/ext/fs.rs
index 4f7cf6018d90f..8fbd78883c04b 100644
--- a/library/std/src/sys/wasi/ext/fs.rs
+++ b/library/std/src/sys/wasi/ext/fs.rs
@@ -6,11 +6,12 @@
 use crate::fs::{self, File, Metadata, OpenOptions};
 use crate::io::{self, IoSlice, IoSliceMut};
 use crate::path::{Path, PathBuf};
+use crate::sealed::Sealed;
 use crate::sys::fs::osstr2str;
 use crate::sys_common::{AsInner, AsInnerMut, FromInner};
 
 /// WASI-specific extensions to [`File`].
-pub trait FileExt {
+pub trait FileExt: Sealed {
     /// Reads a number of bytes starting from a given offset.
     ///
     /// Returns the number of bytes read.
@@ -275,7 +276,7 @@ impl FileExt for fs::File {
 }
 
 /// WASI-specific extensions to [`fs::OpenOptions`].
-pub trait OpenOptionsExt {
+pub trait OpenOptionsExt: Sealed {
     /// Pass custom `dirflags` argument to `path_open`.
     ///
     /// This option configures the `dirflags` argument to the
@@ -390,7 +391,7 @@ impl OpenOptionsExt for OpenOptions {
 }
 
 /// WASI-specific extensions to [`fs::Metadata`].
-pub trait MetadataExt {
+pub trait MetadataExt: Sealed {
     /// Returns the `st_dev` field of the internal `filestat_t`
     fn dev(&self) -> u64;
     /// Returns the `st_ino` field of the internal `filestat_t`
@@ -430,7 +431,7 @@ impl MetadataExt for fs::Metadata {
 ///
 /// Adds support for special WASI file types such as block/character devices,
 /// pipes, and sockets.
-pub trait FileTypeExt {
+pub trait FileTypeExt: Sealed {
     /// Returns `true` if this file type is a block device.
     fn is_block_device(&self) -> bool;
     /// Returns `true` if this file type is a character device.
@@ -457,7 +458,7 @@ impl FileTypeExt for fs::FileType {
 }
 
 /// WASI-specific extension methods for [`fs::DirEntry`].
-pub trait DirEntryExt {
+pub trait DirEntryExt: Sealed {
     /// Returns the underlying `d_ino` field of the `dirent_t`
     fn ino(&self) -> u64;
 }
diff --git a/library/std/src/sys/windows/ext/fs.rs b/library/std/src/sys/windows/ext/fs.rs
index b20eafb4d53a5..cb1ab97c8a50c 100644
--- a/library/std/src/sys/windows/ext/fs.rs
+++ b/library/std/src/sys/windows/ext/fs.rs
@@ -5,12 +5,13 @@
 use crate::fs::{self, Metadata, OpenOptions};
 use crate::io;
 use crate::path::Path;
+use crate::sealed::Sealed;
 use crate::sys;
 use crate::sys_common::{AsInner, AsInnerMut};
 
 /// Windows-specific extensions to [`fs::File`].
 #[stable(feature = "file_offset", since = "1.15.0")]
-pub trait FileExt {
+pub trait FileExt: Sealed {
     /// Seeks to a given position and reads a number of bytes.
     ///
     /// Returns the number of bytes read.
@@ -93,7 +94,7 @@ impl FileExt for fs::File {
 
 /// Windows-specific extensions to [`fs::OpenOptions`].
 #[stable(feature = "open_options_ext", since = "1.10.0")]
-pub trait OpenOptionsExt {
+pub trait OpenOptionsExt: Sealed {
     /// Overrides the `dwDesiredAccess` argument to the call to [`CreateFile`]
     /// with the specified value.
     ///
@@ -294,7 +295,7 @@ impl OpenOptionsExt for OpenOptions {
 /// [`BY_HANDLE_FILE_INFORMATION`]:
 ///     https://docs.microsoft.com/en-us/windows/win32/api/fileapi/ns-fileapi-by_handle_file_information
 #[stable(feature = "metadata_ext", since = "1.1.0")]
-pub trait MetadataExt {
+pub trait MetadataExt: Sealed {
     /// Returns the value of the `dwFileAttributes` field of this metadata.
     ///
     /// This field contains the file system attribute information for a file
@@ -498,7 +499,7 @@ impl MetadataExt for Metadata {
 ///
 /// On Windows, a symbolic link knows whether it is a file or directory.
 #[unstable(feature = "windows_file_type_ext", issue = "none")]
-pub trait FileTypeExt {
+pub trait FileTypeExt: Sealed {
     /// Returns `true` if this file type is a symbolic link that is also a directory.
     #[unstable(feature = "windows_file_type_ext", issue = "none")]
     fn is_symlink_dir(&self) -> bool;