Auto merge of #97063 - Dylan-DPC:rollup-u5el7hb, r=Dylan-DPC

Rollup of 4 pull requests

Successful merges:

 - #96947 (Add rustc_nonnull_optimization_guaranteed to Owned/Borrowed Fd/Socket)
 - #97021 (Added note in documentation)
 - #97042 (Add new eslint rule about brace style)
 - #97060 (Fix use of SetHandleInformation on UWP)

Failed merges:

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

8 files changed, 62 insertions, 1 deletions

diff --git a/library/std/src/os/fd/owned.rs b/library/std/src/os/fd/owned.rs
index bfc5ce01564..53433823fbd 100644
--- a/library/std/src/os/fd/owned.rs
+++ b/library/std/src/os/fd/owned.rs
@@ -32,6 +32,7 @@ use crate::sys_common::{AsInner, FromInner, IntoInner};
 // 32-bit c_int. Below is -2, in two's complement, but that only works out
 // because c_int is 32 bits.
 #[rustc_layout_scalar_valid_range_end(0xFF_FF_FF_FE)]
+#[rustc_nonnull_optimization_guaranteed]
 #[unstable(feature = "io_safety", issue = "87074")]
 pub struct BorrowedFd<'fd> {
     fd: RawFd,
@@ -52,6 +53,7 @@ pub struct BorrowedFd<'fd> {
 // 32-bit c_int. Below is -2, in two's complement, but that only works out
 // because c_int is 32 bits.
 #[rustc_layout_scalar_valid_range_end(0xFF_FF_FF_FE)]
+#[rustc_nonnull_optimization_guaranteed]
 #[unstable(feature = "io_safety", issue = "87074")]
 pub struct OwnedFd {
     fd: RawFd,
diff --git a/library/std/src/os/fd/tests.rs b/library/std/src/os/fd/tests.rs
index 26ef93e3d71..b39863644f1 100644
--- a/library/std/src/os/fd/tests.rs
+++ b/library/std/src/os/fd/tests.rs
@@ -32,3 +32,22 @@ fn test_fd() {
     assert_eq!(stdin_as_file.as_fd().as_raw_fd(), raw_fd);
     assert_eq!(Into::<OwnedFd>::into(stdin_as_file).into_raw_fd(), raw_fd);
 }
+
+#[cfg(any(unix, target_os = "wasi"))]
+#[test]
+fn test_niche_optimizations() {
+    use crate::mem::size_of;
+    #[cfg(unix)]
+    use crate::os::unix::io::{BorrowedFd, FromRawFd, IntoRawFd, OwnedFd, RawFd};
+    #[cfg(target_os = "wasi")]
+    use crate::os::wasi::io::{BorrowedFd, FromRawFd, IntoRawFd, OwnedFd, RawFd};
+
+    assert_eq!(size_of::<Option<OwnedFd>>(), size_of::<RawFd>());
+    assert_eq!(size_of::<Option<BorrowedFd<'static>>>(), size_of::<RawFd>());
+    unsafe {
+        assert_eq!(OwnedFd::from_raw_fd(RawFd::MIN).into_raw_fd(), RawFd::MIN);
+        assert_eq!(OwnedFd::from_raw_fd(RawFd::MAX).into_raw_fd(), RawFd::MAX);
+        assert_eq!(Some(OwnedFd::from_raw_fd(RawFd::MIN)).unwrap().into_raw_fd(), RawFd::MIN);
+        assert_eq!(Some(OwnedFd::from_raw_fd(RawFd::MAX)).unwrap().into_raw_fd(), RawFd::MAX);
+    }
+}
diff --git a/library/std/src/os/windows/io/handle.rs b/library/std/src/os/windows/io/handle.rs
index f27970eaaf1..0ecac6b4475 100644
--- a/library/std/src/os/windows/io/handle.rs
+++ b/library/std/src/os/windows/io/handle.rs
@@ -206,6 +206,7 @@ impl OwnedHandle {
     }
 
     /// Allow child processes to inherit the handle.
+    #[cfg(not(target_vendor = "uwp"))]
     pub(crate) fn set_inheritable(&self) -> io::Result<()> {
         cvt(unsafe {
             c::SetHandleInformation(
diff --git a/library/std/src/os/windows/io/mod.rs b/library/std/src/os/windows/io/mod.rs
index 2f6f0769548..3325688e661 100644
--- a/library/std/src/os/windows/io/mod.rs
+++ b/library/std/src/os/windows/io/mod.rs
@@ -54,3 +54,6 @@ pub use handle::*;
 pub use raw::*;
 #[unstable(feature = "io_safety", issue = "87074")]
 pub use socket::*;
+
+#[cfg(test)]
+mod tests;
diff --git a/library/std/src/os/windows/io/socket.rs b/library/std/src/os/windows/io/socket.rs
index c14a1d6192f..e23e1cf8cee 100644
--- a/library/std/src/os/windows/io/socket.rs
+++ b/library/std/src/os/windows/io/socket.rs
@@ -10,6 +10,7 @@ use crate::mem;
 use crate::mem::forget;
 use crate::sys;
 use crate::sys::c;
+#[cfg(not(target_vendor = "uwp"))]
 use crate::sys::cvt;
 
 /// A borrowed socket.
@@ -34,6 +35,7 @@ use crate::sys::cvt;
     target_pointer_width = "64",
     rustc_layout_scalar_valid_range_end(0xFF_FF_FF_FF_FF_FF_FF_FE)
 )]
+#[rustc_nonnull_optimization_guaranteed]
 #[unstable(feature = "io_safety", issue = "87074")]
 pub struct BorrowedSocket<'socket> {
     socket: RawSocket,
@@ -56,6 +58,7 @@ pub struct BorrowedSocket<'socket> {
     target_pointer_width = "64",
     rustc_layout_scalar_valid_range_end(0xFF_FF_FF_FF_FF_FF_FF_FE)
 )]
+#[rustc_nonnull_optimization_guaranteed]
 #[unstable(feature = "io_safety", issue = "87074")]
 pub struct OwnedSocket {
     socket: RawSocket,
diff --git a/library/std/src/os/windows/io/tests.rs b/library/std/src/os/windows/io/tests.rs
new file mode 100644
index 00000000000..41734e52e8c
--- /dev/null
+++ b/library/std/src/os/windows/io/tests.rs
@@ -0,0 +1,21 @@
+#[test]
+fn test_niche_optimizations_socket() {
+    use crate::mem::size_of;
+    use crate::os::windows::io::{
+        BorrowedSocket, FromRawSocket, IntoRawSocket, OwnedSocket, RawSocket,
+    };
+
+    assert_eq!(size_of::<Option<OwnedSocket>>(), size_of::<RawSocket>());
+    assert_eq!(size_of::<Option<BorrowedSocket<'static>>>(), size_of::<RawSocket>(),);
+    unsafe {
+        #[cfg(target_pointer_width = "32")]
+        let (min, max) = (i32::MIN as u32, i32::MAX as u32);
+        #[cfg(target_pointer_width = "64")]
+        let (min, max) = (i64::MIN as u64, i64::MAX as u64);
+
+        assert_eq!(OwnedSocket::from_raw_socket(min).into_raw_socket(), min);
+        assert_eq!(OwnedSocket::from_raw_socket(max).into_raw_socket(), max);
+        assert_eq!(Some(OwnedSocket::from_raw_socket(min)).unwrap().into_raw_socket(), min);
+        assert_eq!(Some(OwnedSocket::from_raw_socket(max)).unwrap().into_raw_socket(), max);
+    }
+}
diff --git a/library/std/src/sys/windows/handle.rs b/library/std/src/sys/windows/handle.rs
index 3b609825a79..c319cb28630 100644
--- a/library/std/src/sys/windows/handle.rs
+++ b/library/std/src/sys/windows/handle.rs
@@ -221,6 +221,7 @@ impl Handle {
         Ok(Self(self.0.duplicate(access, inherit, options)?))
     }
 
+    #[cfg(not(target_vendor = "uwp"))]
     pub(crate) fn set_inheritable(&self) -> io::Result<()> {
         self.0.set_inheritable()
     }
diff --git a/library/std/src/sys/windows/pipe.rs b/library/std/src/sys/windows/pipe.rs
index 928bf2439c3..2c586f1abe4 100644
--- a/library/std/src/sys/windows/pipe.rs
+++ b/library/std/src/sys/windows/pipe.rs
@@ -57,10 +57,21 @@ impl Pipes {
             } else {
                 let (ours, theirs) = if ours_readable { (read, write) } else { (write, read) };
                 let ours = Handle::from_raw_handle(ours);
+                #[cfg(not(target_vendor = "uwp"))]
                 let theirs = Handle::from_raw_handle(theirs);
+                #[cfg(target_vendor = "uwp")]
+                let mut theirs = Handle::from_raw_handle(theirs);
 
                 if their_handle_inheritable {
-                    theirs.set_inheritable()?;
+                    #[cfg(not(target_vendor = "uwp"))]
+                    {
+                        theirs.set_inheritable()?;
+                    }
+
+                    #[cfg(target_vendor = "uwp")]
+                    {
+                        theirs = theirs.duplicate(0, true, c::DUPLICATE_SAME_ACCESS)?;
+                    }
                 }
 
                 Ok(Pipes { ours: AnonPipe::Sync(ours), theirs: AnonPipe::Sync(theirs) })