Auto merge of #138595 - jhpratt:rollup-09pvfzu, r=jhpratt

Rollup of 9 pull requests

Successful merges:

 - #136355 (Add `*_value` methods to proc_macro lib)
 - #137621 (Add std support to cygwin target)
 - #137793 (Stablize anonymous pipe)
 - #138341 (std: Mention clone-on-write mutation in Arc<T>)
 - #138517 (Improve upvar analysis for deref of child capture)
 - #138584 (Update Rust Foundation links in Readme)
 - #138586 (Document `#![register_tool]`)
 - #138590 (Flatten and simplify some control flow 🫓)
 - #138592 (update change entry for #137147)

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

4 files changed, 8 insertions, 2 deletions

diff --git a/library/std/src/os/unix/net/datagram.rs b/library/std/src/os/unix/net/datagram.rs
index 82446ea107f..7735637c840 100644
--- a/library/std/src/os/unix/net/datagram.rs
+++ b/library/std/src/os/unix/net/datagram.rs
@@ -9,6 +9,7 @@
     target_os = "illumos",
     target_os = "haiku",
     target_os = "nto",
+    target_os = "cygwin"
 ))]
 use libc::MSG_NOSIGNAL;
 
@@ -37,6 +38,7 @@ use crate::{fmt, io};
     target_os = "illumos",
     target_os = "haiku",
     target_os = "nto",
+    target_os = "cygwin"
 )))]
 const MSG_NOSIGNAL: core::ffi::c_int = 0x0;
 
diff --git a/library/std/src/os/unix/net/mod.rs b/library/std/src/os/unix/net/mod.rs
index 3e45e3533ed..6cd62303a53 100644
--- a/library/std/src/os/unix/net/mod.rs
+++ b/library/std/src/os/unix/net/mod.rs
@@ -21,6 +21,7 @@ mod tests;
     target_os = "openbsd",
     target_os = "nto",
     target_vendor = "apple",
+    target_os = "cygwin"
 ))]
 mod ucred;
 
@@ -44,6 +45,7 @@ pub use self::stream::*;
     target_os = "openbsd",
     target_os = "nto",
     target_vendor = "apple",
+    target_os = "cygwin",
 ))]
 #[unstable(feature = "peer_credentials_unix_socket", issue = "42839", reason = "unstable")]
 pub use self::ucred::*;
diff --git a/library/std/src/os/unix/net/stream.rs b/library/std/src/os/unix/net/stream.rs
index cb210b41eae..1cab04a454d 100644
--- a/library/std/src/os/unix/net/stream.rs
+++ b/library/std/src/os/unix/net/stream.rs
@@ -10,6 +10,7 @@ use super::{SocketAncillary, recv_vectored_with_ancillary_from, send_vectored_wi
     target_os = "openbsd",
     target_os = "nto",
     target_vendor = "apple",
+    target_os = "cygwin"
 ))]
 use super::{UCred, peer_cred};
 use crate::fmt;
@@ -231,6 +232,7 @@ impl UnixStream {
         target_os = "openbsd",
         target_os = "nto",
         target_vendor = "apple",
+        target_os = "cygwin"
     ))]
     pub fn peer_cred(&self) -> io::Result<UCred> {
         peer_cred(self)
diff --git a/library/std/src/os/unix/net/ucred.rs b/library/std/src/os/unix/net/ucred.rs
index 2dd7d409e48..36fb9c46b4a 100644
--- a/library/std/src/os/unix/net/ucred.rs
+++ b/library/std/src/os/unix/net/ucred.rs
@@ -33,10 +33,10 @@ pub(super) use self::impl_apple::peer_cred;
     target_os = "nto"
 ))]
 pub(super) use self::impl_bsd::peer_cred;
-#[cfg(any(target_os = "android", target_os = "linux"))]
+#[cfg(any(target_os = "android", target_os = "linux", target_os = "cygwin"))]
 pub(super) use self::impl_linux::peer_cred;
 
-#[cfg(any(target_os = "linux", target_os = "android"))]
+#[cfg(any(target_os = "linux", target_os = "android", target_os = "cygwin"))]
 mod impl_linux {
     use libc::{SO_PEERCRED, SOL_SOCKET, c_void, getsockopt, socklen_t, ucred};