Rollup merge of #130962 - nyurik:opts-libs, r=cuviper

Migrate lib's `&Option<T>` into `Option<&T>`

Trying out my new lint https://github.com/rust-lang/rust-clippy/pull/13336 - according to the [video](https://www.youtube.com/watch?v=6c7pZYP_iIE), this could lead to some performance and memory optimizations.

Basic thoughts expressed in the video that seem to make sense:
* `&Option<T>` in an API breaks encapsulation:
  * caller must own T and move it into an Option to call with it
  * if returned, the owner must store it as Option<T> internally in order to return it
* Performance is subject to compiler optimization, but at the basics, `&Option<T>` points to memory that has `presence` flag + value, whereas `Option<&T>` by specification is always optimized to a single pointer.

4 files changed, 11 insertions, 11 deletions

diff --git a/library/std/src/sys/pal/sgx/net.rs b/library/std/src/sys/pal/sgx/net.rs
index 44913ffe3a9..c966886d163 100644
--- a/library/std/src/sys/pal/sgx/net.rs
+++ b/library/std/src/sys/pal/sgx/net.rs
@@ -78,9 +78,8 @@ fn io_err_to_addr(result: io::Result<&SocketAddr>) -> io::Result<String> {
     }
 }
 
-fn addr_to_sockaddr(addr: &Option<String>) -> io::Result<SocketAddr> {
-    addr.as_ref()
-        .ok_or(io::ErrorKind::AddrNotAvailable)?
+fn addr_to_sockaddr(addr: Option<&str>) -> io::Result<SocketAddr> {
+    addr.ok_or(io::ErrorKind::AddrNotAvailable)?
         .to_socket_addrs()
         // unwrap OK: if an iterator is returned, we're guaranteed to get exactly one entry
         .map(|mut it| it.next().unwrap())
@@ -161,11 +160,11 @@ impl TcpStream {
     }
 
     pub fn peer_addr(&self) -> io::Result<SocketAddr> {
-        addr_to_sockaddr(&self.peer_addr)
+        addr_to_sockaddr(self.peer_addr.as_deref())
     }
 
     pub fn socket_addr(&self) -> io::Result<SocketAddr> {
-        addr_to_sockaddr(&self.inner.local_addr)
+        addr_to_sockaddr(self.inner.local_addr.as_deref())
     }
 
     pub fn shutdown(&self, _: Shutdown) -> io::Result<()> {
@@ -255,13 +254,14 @@ impl TcpListener {
     }
 
     pub fn socket_addr(&self) -> io::Result<SocketAddr> {
-        addr_to_sockaddr(&self.inner.local_addr)
+        addr_to_sockaddr(self.inner.local_addr.as_deref())
     }
 
     pub fn accept(&self) -> io::Result<(TcpStream, SocketAddr)> {
         let (fd, local_addr, peer_addr) = usercalls::accept_stream(self.inner.inner.raw())?;
         let peer_addr = Some(peer_addr);
-        let ret_peer = addr_to_sockaddr(&peer_addr).unwrap_or_else(|_| ([0; 4], 0).into());
+        let ret_peer =
+            addr_to_sockaddr(peer_addr.as_deref()).unwrap_or_else(|_| ([0; 4], 0).into());
         Ok((TcpStream { inner: Socket::new(fd, local_addr), peer_addr }, ret_peer))
     }
 
diff --git a/library/std/src/sys/pal/unix/process/process_common.rs b/library/std/src/sys/pal/unix/process/process_common.rs
index d9c41d43487..13290fed762 100644
--- a/library/std/src/sys/pal/unix/process/process_common.rs
+++ b/library/std/src/sys/pal/unix/process/process_common.rs
@@ -312,8 +312,8 @@ impl Command {
     }
 
     #[allow(dead_code)]
-    pub fn get_cwd(&self) -> &Option<CString> {
-        &self.cwd
+    pub fn get_cwd(&self) -> Option<&CStr> {
+        self.cwd.as_deref()
     }
     #[allow(dead_code)]
     pub fn get_uid(&self) -> Option<uid_t> {
diff --git a/library/std/src/sys/pal/unix/process/process_unix.rs b/library/std/src/sys/pal/unix/process/process_unix.rs
index 5d30f388da1..4551d49e841 100644
--- a/library/std/src/sys/pal/unix/process/process_unix.rs
+++ b/library/std/src/sys/pal/unix/process/process_unix.rs
@@ -335,7 +335,7 @@ impl Command {
                 cvt(libc::setuid(u as uid_t))?;
             }
         }
-        if let Some(ref cwd) = *self.get_cwd() {
+        if let Some(cwd) = self.get_cwd() {
             cvt(libc::chdir(cwd.as_ptr()))?;
         }
 
diff --git a/library/std/src/sys/pal/unix/process/process_vxworks.rs b/library/std/src/sys/pal/unix/process/process_vxworks.rs
index 2d9a304c495..38daf6af918 100644
--- a/library/std/src/sys/pal/unix/process/process_vxworks.rs
+++ b/library/std/src/sys/pal/unix/process/process_vxworks.rs
@@ -57,7 +57,7 @@ impl Command {
                 t!(cvt_r(|| libc::dup2(fd, libc::STDERR_FILENO)));
             }
 
-            if let Some(ref cwd) = *self.get_cwd() {
+            if let Some(cwd) = self.get_cwd() {
                 t!(cvt(libc::chdir(cwd.as_ptr())));
             }