Auto merge of #82153 - jonas-schievink:rollup-ls5r943, r=jonas-schievink

Rollup of 19 pull requests

Successful merges:

 - #81503 (Suggest to create a new `const` item if the `fn` in the array is a `const fn`)
 - #81897 (Add match pattern diagnostics regression test)
 - #81975 (Seal the CommandExt, OsStrExt and OsStringExt traits)
 - #82009 (const_generics: Dont evaluate array length const when handling errors)
 - #82060 (Fix typos in BTreeSet::{first, last} docs)
 - #82061 (CTFE validation: catch ReadPointerAsBytes and better error)
 - #82063 (Fixed minor typo in catch_unwind docs)
 - #82067 (const_generics: Fix incorrect ty::ParamEnv::empty() usage)
 - #82077 (Edit `rustc_arena::DropArena` docs)
 - #82096 (Fix a typo)
 - #82106 (Remove unnecessary `Option` in `default_doc`)
 - #82107 (expand: Some cleanup)
 - #82118 (Add missing env!-decl variant)
 - #82119 (Fix typo in link to CreateSymbolicLinkW documentation.)
 - #82120 (Stabilize Arguments::as_str)
 - #82129 (Remove redundant bool_to_option feature gate)
 - #82133 (Update link for extern prelude.)
 - #82141 (32-bit ARM: Emit `lr` instead of `r14` when specified as an `asm!` output register.)
 - #82147 (:arrow_up: rust-analyzer)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

9 files changed, 56 insertions, 33 deletions

diff --git a/library/std/src/ffi/os_str.rs b/library/std/src/ffi/os_str.rs
index c9c8f68cd9c..5bb3f6bdcfd 100644
--- a/library/std/src/ffi/os_str.rs
+++ b/library/std/src/ffi/os_str.rs
@@ -76,6 +76,10 @@ pub struct OsString {
     inner: Buf,
 }
 
+/// Allows extension traits within `std`.
+#[unstable(feature = "sealed", issue = "none")]
+impl crate::sealed::Sealed for OsString {}
+
 /// Borrowed reference to an OS string (see [`OsString`]).
 ///
 /// This type represents a borrowed reference to a string in the operating system's preferred
@@ -100,6 +104,10 @@ pub struct OsStr {
     inner: Slice,
 }
 
+/// Allows extension traits within `std`.
+#[unstable(feature = "sealed", issue = "none")]
+impl crate::sealed::Sealed for OsStr {}
+
 impl OsString {
     /// Constructs a new empty `OsString`.
     ///
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 961cff661e3..bc9b4702941 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -264,7 +264,6 @@
 #![feature(exhaustive_patterns)]
 #![feature(extend_one)]
 #![feature(external_doc)]
-#![feature(fmt_as_str)]
 #![feature(fn_traits)]
 #![feature(format_args_nl)]
 #![feature(gen_future)]
@@ -582,3 +581,11 @@ include!("keyword_docs.rs");
 // is unconditional, so the unstable feature needs to be defined somewhere.
 #[unstable(feature = "restricted_std", issue = "none")]
 mod __restricted_std_workaround {}
+
+mod sealed {
+    /// This trait being unreachable from outside the crate
+    /// prevents outside implementations of our extension traits.
+    /// This allows adding more trait methods in the future.
+    #[unstable(feature = "sealed", issue = "none")]
+    pub trait Sealed {}
+}
diff --git a/library/std/src/panic.rs b/library/std/src/panic.rs
index 89a822a7229..3e634239ad3 100644
--- a/library/std/src/panic.rs
+++ b/library/std/src/panic.rs
@@ -408,7 +408,7 @@ impl<S: Stream> Stream for AssertUnwindSafe<S> {
 /// aborting the process as well. This function *only* catches unwinding panics,
 /// not those that abort the process.
 ///
-/// Also note that unwinding into Rust code with a foreign exception (e.g. a
+/// Also note that unwinding into Rust code with a foreign exception (e.g.
 /// an exception thrown from C++ code) is undefined behavior.
 ///
 /// # Examples
diff --git a/library/std/src/process.rs b/library/std/src/process.rs
index fb78e62834a..6480e654c55 100644
--- a/library/std/src/process.rs
+++ b/library/std/src/process.rs
@@ -498,6 +498,10 @@ pub struct Command {
     inner: imp::Command,
 }
 
+/// Allows extension traits within `std`.
+#[unstable(feature = "sealed", issue = "none")]
+impl crate::sealed::Sealed for Command {}
+
 impl Command {
     /// Constructs a new `Command` for launching the program at
     /// path `program`, with the following default configuration:
@@ -1375,6 +1379,10 @@ impl From<fs::File> for Stdio {
 #[stable(feature = "process", since = "1.0.0")]
 pub struct ExitStatus(imp::ExitStatus);
 
+/// Allows extension traits within `std`.
+#[unstable(feature = "sealed", issue = "none")]
+impl crate::sealed::Sealed for ExitStatus {}
+
 impl ExitStatus {
     /// Was termination successful? Signal termination is not considered a
     /// success, and success is defined as a zero exit status.
diff --git a/library/std/src/sys/unix/ext/process.rs b/library/std/src/sys/unix/ext/process.rs
index 724b5dcca6a..7559c1f1d9e 100644
--- a/library/std/src/sys/unix/ext/process.rs
+++ b/library/std/src/sys/unix/ext/process.rs
@@ -6,20 +6,16 @@ use crate::ffi::OsStr;
 use crate::io;
 use crate::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
 use crate::process;
+use crate::sealed::Sealed;
 use crate::sys;
 use crate::sys_common::{AsInner, AsInnerMut, FromInner, IntoInner};
 
-mod private {
-    /// This trait being unreachable from outside the crate
-    /// prevents other implementations of the `ExitStatusExt` trait,
-    /// which allows potentially adding more trait methods in the future.
-    #[stable(feature = "none", since = "1.51.0")]
-    pub trait Sealed {}
-}
-
 /// Unix-specific extensions to the [`process::Command`] builder.
+///
+/// This trait is sealed: it cannot be implemented outside the standard library.
+/// This is so that future additional methods are not breaking changes.
 #[stable(feature = "rust1", since = "1.0.0")]
-pub trait CommandExt {
+pub trait CommandExt: Sealed {
     /// Sets the child process's user ID. This translates to a
     /// `setuid` call in the child process. Failure in the `setuid`
     /// call will cause the spawn to fail.
@@ -193,7 +189,7 @@ impl CommandExt for process::Command {
 /// This trait is sealed: it cannot be implemented outside the standard library.
 /// This is so that future additional methods are not breaking changes.
 #[stable(feature = "rust1", since = "1.0.0")]
-pub trait ExitStatusExt: private::Sealed {
+pub trait ExitStatusExt: Sealed {
     /// Creates a new `ExitStatus` from the raw underlying `i32` return value of
     /// a process.
     #[stable(feature = "exit_status_from", since = "1.12.0")]
@@ -228,9 +224,6 @@ pub trait ExitStatusExt: private::Sealed {
     fn into_raw(self) -> i32;
 }
 
-#[stable(feature = "none", since = "1.51.0")]
-impl private::Sealed for process::ExitStatus {}
-
 #[stable(feature = "rust1", since = "1.0.0")]
 impl ExitStatusExt for process::ExitStatus {
     fn from_raw(raw: i32) -> Self {
diff --git a/library/std/src/sys/windows/c.rs b/library/std/src/sys/windows/c.rs
index dec88620810..9789ed085e2 100644
--- a/library/std/src/sys/windows/c.rs
+++ b/library/std/src/sys/windows/c.rs
@@ -1023,7 +1023,7 @@ extern "system" {
     pub fn HeapFree(hHeap: HANDLE, dwFlags: DWORD, lpMem: LPVOID) -> BOOL;
 
     // >= Vista / Server 2008
-    // https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createsymboliclinka
+    // https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-createsymboliclinkw
     pub fn CreateSymbolicLinkW(
         lpSymlinkFileName: LPCWSTR,
         lpTargetFileName: LPCWSTR,
diff --git a/library/std/src/sys/windows/ext/ffi.rs b/library/std/src/sys/windows/ext/ffi.rs
index 1df2a0df143..c89b9ff1efa 100644
--- a/library/std/src/sys/windows/ext/ffi.rs
+++ b/library/std/src/sys/windows/ext/ffi.rs
@@ -53,6 +53,7 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use crate::ffi::{OsStr, OsString};
+use crate::sealed::Sealed;
 use crate::sys::os_str::Buf;
 use crate::sys_common::wtf8::Wtf8Buf;
 use crate::sys_common::{AsInner, FromInner};
@@ -61,8 +62,11 @@ use crate::sys_common::{AsInner, FromInner};
 pub use crate::sys_common::wtf8::EncodeWide;
 
 /// Windows-specific extensions to [`OsString`].
+///
+/// This trait is sealed: it cannot be implemented outside the standard library.
+/// This is so that future additional methods are not breaking changes.
 #[stable(feature = "rust1", since = "1.0.0")]
-pub trait OsStringExt {
+pub trait OsStringExt: Sealed {
     /// Creates an `OsString` from a potentially ill-formed UTF-16 slice of
     /// 16-bit code units.
     ///
@@ -92,8 +96,11 @@ impl OsStringExt for OsString {
 }
 
 /// Windows-specific extensions to [`OsStr`].
+///
+/// This trait is sealed: it cannot be implemented outside the standard library.
+/// This is so that future additional methods are not breaking changes.
 #[stable(feature = "rust1", since = "1.0.0")]
-pub trait OsStrExt {
+pub trait OsStrExt: Sealed {
     /// Re-encodes an `OsStr` as a wide character sequence, i.e., potentially
     /// ill-formed UTF-16.
     ///
diff --git a/library/std/src/sys/windows/ext/process.rs b/library/std/src/sys/windows/ext/process.rs
index 7a92381d660..3d680a7f2d9 100644
--- a/library/std/src/sys/windows/ext/process.rs
+++ b/library/std/src/sys/windows/ext/process.rs
@@ -4,17 +4,10 @@
 
 use crate::os::windows::io::{AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle};
 use crate::process;
+use crate::sealed::Sealed;
 use crate::sys;
 use crate::sys_common::{AsInner, AsInnerMut, FromInner, IntoInner};
 
-mod private {
-    /// This trait being unreachable from outside the crate
-    /// prevents other implementations of the `ExitStatusExt` trait,
-    /// which allows potentially adding more trait methods in the future.
-    #[stable(feature = "none", since = "1.51.0")]
-    pub trait Sealed {}
-}
-
 #[stable(feature = "process_extensions", since = "1.2.0")]
 impl FromRawHandle for process::Stdio {
     unsafe fn from_raw_handle(handle: RawHandle) -> process::Stdio {
@@ -85,7 +78,7 @@ impl IntoRawHandle for process::ChildStderr {
 /// This trait is sealed: it cannot be implemented outside the standard library.
 /// This is so that future additional methods are not breaking changes.
 #[stable(feature = "exit_status_from", since = "1.12.0")]
-pub trait ExitStatusExt: private::Sealed {
+pub trait ExitStatusExt: Sealed {
     /// Creates a new `ExitStatus` from the raw underlying `u32` return value of
     /// a process.
     #[stable(feature = "exit_status_from", since = "1.12.0")]
@@ -99,12 +92,12 @@ impl ExitStatusExt for process::ExitStatus {
     }
 }
 
-#[stable(feature = "none", since = "1.51.0")]
-impl private::Sealed for process::ExitStatus {}
-
 /// Windows-specific extensions to the [`process::Command`] builder.
+///
+/// This trait is sealed: it cannot be implemented outside the standard library.
+/// This is so that future additional methods are not breaking changes.
 #[stable(feature = "windows_process_extensions", since = "1.16.0")]
-pub trait CommandExt {
+pub trait CommandExt: Sealed {
     /// Sets the [process creation flags][1] to be passed to `CreateProcess`.
     ///
     /// These will always be ORed with `CREATE_UNICODE_ENVIRONMENT`.
diff --git a/library/std/src/sys_common/os_str_bytes.rs b/library/std/src/sys_common/os_str_bytes.rs
index 497e5fc7bdd..302c5197407 100644
--- a/library/std/src/sys_common/os_str_bytes.rs
+++ b/library/std/src/sys_common/os_str_bytes.rs
@@ -6,6 +6,7 @@ use crate::ffi::{OsStr, OsString};
 use crate::fmt;
 use crate::mem;
 use crate::rc::Rc;
+use crate::sealed::Sealed;
 use crate::str;
 use crate::sync::Arc;
 use crate::sys_common::bytestring::debug_fmt_bytestring;
@@ -232,8 +233,11 @@ impl Slice {
 }
 
 /// Platform-specific extensions to [`OsString`].
+///
+/// This trait is sealed: it cannot be implemented outside the standard library.
+/// This is so that future additional methods are not breaking changes.
 #[stable(feature = "rust1", since = "1.0.0")]
-pub trait OsStringExt {
+pub trait OsStringExt: Sealed {
     /// Creates an [`OsString`] from a byte vector.
     ///
     /// See the module documentation for an example.
@@ -258,8 +262,11 @@ impl OsStringExt for OsString {
 }
 
 /// Platform-specific extensions to [`OsStr`].
+///
+/// This trait is sealed: it cannot be implemented outside the standard library.
+/// This is so that future additional methods are not breaking changes.
 #[stable(feature = "rust1", since = "1.0.0")]
-pub trait OsStrExt {
+pub trait OsStrExt: Sealed {
     #[stable(feature = "rust1", since = "1.0.0")]
     /// Creates an [`OsStr`] from a byte slice.
     ///