Auto merge of rust-lang#121569 - matthiaskrgr:rollup-awglrax, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - rust-lang#121343 (Add examples for some methods on slices)
 - rust-lang#121374 (match lowering: Split off `test_candidates` into several functions and improve comments)
 - rust-lang#121474 (Ignore compiletest test directive migration commits)
 - rust-lang#121515 (promotion: don't promote int::MIN / -1)
 - rust-lang#121530 (Fix incorrect doc of ScopedJoinHandle::is_finished)
 - rust-lang#121551 (Forbid use of `extern "C-unwind"` inside standard library)
 - rust-lang#121556 (Use `addr_of!`)

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

Author: bors

alloc/src/boxed/thin.rs

@@ -176,7 +176,7 @@ impl<T: ?Sized> ThinBox<T> {
 
     fn with_header(&self) -> &WithHeader<<T as Pointee>::Metadata> {
         // SAFETY: both types are transparent to `NonNull<u8>`
-        unsafe { &*((&self.ptr) as *const WithOpaqueHeader as *const WithHeader<_>) }
+        unsafe { &*(core::ptr::addr_of!(self.ptr) as *const WithHeader<_>) }
     }
 }
 

alloc/src/lib.rs

@@ -92,6 +92,7 @@
 #![warn(multiple_supertrait_upcastable)]
 #![allow(internal_features)]
 #![allow(rustdoc::redundant_explicit_links)]
+#![deny(ffi_unwind_calls)]
 //
 // Library features:
 // tidy-alphabetical-start

alloc/src/rc.rs

@@ -1969,7 +1969,7 @@ impl<T: ?Sized, A: Allocator> Rc<T, A> {
 
             // Copy value as bytes
             ptr::copy_nonoverlapping(
-                &*src as *const T as *const u8,
+                core::ptr::addr_of!(*src) as *const u8,
                 ptr::addr_of_mut!((*ptr).value) as *mut u8,
                 value_size,
             );
@@ -2440,7 +2440,7 @@ impl<T: ?Sized + fmt::Debug, A: Allocator> fmt::Debug for Rc<T, A> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized, A: Allocator> fmt::Pointer for Rc<T, A> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Pointer::fmt(&(&**self as *const T), f)
+        fmt::Pointer::fmt(&core::ptr::addr_of!(**self), f)
     }
 }
 

alloc/src/sync.rs

@@ -1914,7 +1914,7 @@ impl<T: ?Sized, A: Allocator> Arc<T, A> {
 
             // Copy value as bytes
             ptr::copy_nonoverlapping(
-                &*src as *const T as *const u8,
+                core::ptr::addr_of!(*src) as *const u8,
                 ptr::addr_of_mut!((*ptr).data) as *mut u8,
                 value_size,
             );
@@ -3265,7 +3265,7 @@ impl<T: ?Sized + fmt::Debug, A: Allocator> fmt::Debug for Arc<T, A> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized, A: Allocator> fmt::Pointer for Arc<T, A> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Pointer::fmt(&(&**self as *const T), f)
+        fmt::Pointer::fmt(&core::ptr::addr_of!(**self), f)
     }
 }
 

core/src/ffi/c_str.rs

@@ -4,6 +4,7 @@ use crate::ffi::c_char;
 use crate::fmt;
 use crate::intrinsics;
 use crate::ops;
+use crate::ptr::addr_of;
 use crate::slice;
 use crate::slice::memchr;
 use crate::str;
@@ -603,7 +604,7 @@ impl CStr {
     pub const fn to_bytes_with_nul(&self) -> &[u8] {
         // SAFETY: Transmuting a slice of `c_char`s to a slice of `u8`s
         // is safe on all supported targets.
-        unsafe { &*(&self.inner as *const [c_char] as *const [u8]) }
+        unsafe { &*(addr_of!(self.inner) as *const [u8]) }
     }
 
     /// Yields a <code>&[str]</code> slice if the `CStr` contains valid UTF-8.

core/src/iter/adapters/filter_map.rs

@@ -2,6 +2,7 @@ use crate::iter::{adapters::SourceIter, FusedIterator, InPlaceIterable, TrustedF
 use crate::mem::{ManuallyDrop, MaybeUninit};
 use crate::num::NonZero;
 use crate::ops::{ControlFlow, Try};
+use crate::ptr::addr_of;
 use crate::{array, fmt};
 
 /// An iterator that uses `f` to both filter and map elements from `iter`.
@@ -98,9 +99,8 @@ where
             // SAFETY: Loop conditions ensure the index is in bounds.
 
             unsafe {
-                let opt_payload_at: *const MaybeUninit<B> = (&val as *const Option<B>)
-                    .byte_add(core::mem::offset_of!(Option<B>, Some.0))
-                    .cast();
+                let opt_payload_at: *const MaybeUninit<B> =
+                    addr_of!(val).byte_add(core::mem::offset_of!(Option<B>, Some.0)).cast();
                 let dst = guard.array.as_mut_ptr().add(idx);
                 crate::ptr::copy_nonoverlapping(opt_payload_at, dst, 1);
                 crate::mem::forget(val);

core/src/lib.rs

@@ -106,6 +106,7 @@
 #![allow(incomplete_features)]
 #![warn(multiple_supertrait_upcastable)]
 #![allow(internal_features)]
+#![deny(ffi_unwind_calls)]
 // Do not check link redundancy on bootstraping phase
 #![allow(rustdoc::redundant_explicit_links)]
 //

core/src/ptr/mod.rs

@@ -1553,7 +1553,7 @@ pub const unsafe fn write_unaligned<T>(dst: *mut T, src: T) {
     // `dst` cannot overlap `src` because the caller has mutable access
     // to `dst` while `src` is owned by this function.
     unsafe {
-        copy_nonoverlapping(&src as *const T as *const u8, dst as *mut u8, mem::size_of::<T>());
+        copy_nonoverlapping(addr_of!(src) as *const u8, dst as *mut u8, mem::size_of::<T>());
         // We are calling the intrinsic directly to avoid function calls in the generated code.
         intrinsics::forget(src);
     }

core/src/slice/mod.rs

@@ -146,6 +146,9 @@ impl<T> [T] {
     /// ```
     /// let a = [1, 2, 3];
     /// assert!(!a.is_empty());
+    ///
+    /// let b: &[i32] = &[];
+    /// assert!(b.is_empty());
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_slice_is_empty", since = "1.39.0")]
@@ -185,6 +188,9 @@ impl<T> [T] {
     ///     *first = 5;
     /// }
     /// assert_eq!(x, &[5, 1, 2]);
+    ///
+    /// let y: &mut [i32] = &mut [];
+    /// assert_eq!(None, y.first_mut());
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_slice_first_last", issue = "83570")]
@@ -297,7 +303,7 @@ impl<T> [T] {
         if let [.., last] = self { Some(last) } else { None }
     }
 
-    /// Returns a mutable reference to the last item in the slice.
+    /// Returns a mutable reference to the last item in the slice, or `None` if it is empty.
     ///
     /// # Examples
     ///
@@ -308,6 +314,9 @@ impl<T> [T] {
     ///     *last = 10;
     /// }
     /// assert_eq!(x, &[0, 1, 10]);
+    ///
+    /// let y: &mut [i32] = &mut [];
+    /// assert_eq!(None, y.last_mut());
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_slice_first_last", issue = "83570")]

proc_macro/src/lib.rs

@@ -36,6 +36,7 @@
 #![feature(strict_provenance)]
 #![recursion_limit = "256"]
 #![allow(internal_features)]
+#![deny(ffi_unwind_calls)]
 
 #[unstable(feature = "proc_macro_internals", issue = "27812")]
 #[doc(hidden)]

std/src/os/unix/net/addr.rs

@@ -21,7 +21,7 @@ mod libc {
 fn sun_path_offset(addr: &libc::sockaddr_un) -> usize {
     // Work with an actual instance of the type since using a null pointer is UB
     let base = (addr as *const libc::sockaddr_un).addr();
-    let path = (&addr.sun_path as *const libc::c_char).addr();
+    let path = core::ptr::addr_of!(addr.sun_path).addr();
     path - base
 }
 
@@ -98,7 +98,7 @@ impl SocketAddr {
         unsafe {
             let mut addr: libc::sockaddr_un = mem::zeroed();
             let mut len = mem::size_of::<libc::sockaddr_un>() as libc::socklen_t;
-            cvt(f(&mut addr as *mut _ as *mut _, &mut len))?;
+            cvt(f(core::ptr::addr_of_mut!(addr) as *mut _, &mut len))?;
             SocketAddr::from_parts(addr, len)
         }
     }

std/src/os/unix/net/ancillary.rs

@@ -37,7 +37,7 @@ pub(super) fn recv_vectored_with_ancillary_from(
     unsafe {
         let mut msg_name: libc::sockaddr_un = zeroed();
         let mut msg: libc::msghdr = zeroed();
-        msg.msg_name = &mut msg_name as *mut _ as *mut _;
+        msg.msg_name = core::ptr::addr_of_mut!(msg_name) as *mut _;
         msg.msg_namelen = size_of::<libc::sockaddr_un>() as libc::socklen_t;
         msg.msg_iov = bufs.as_mut_ptr().cast();
         msg.msg_iovlen = bufs.len() as _;
@@ -70,7 +70,7 @@ pub(super) fn send_vectored_with_ancillary_to(
             if let Some(path) = path { sockaddr_un(path)? } else { (zeroed(), 0) };
 
         let mut msg: libc::msghdr = zeroed();
-        msg.msg_name = &mut msg_name as *mut _ as *mut _;
+        msg.msg_name = core::ptr::addr_of_mut!(msg_name) as *mut _;
         msg.msg_namelen = msg_namelen;
         msg.msg_iov = bufs.as_ptr() as *mut _;
         msg.msg_iovlen = bufs.len() as _;

std/src/os/unix/net/datagram.rs

@@ -91,7 +91,7 @@ impl UnixDatagram {
             let socket = UnixDatagram::unbound()?;
             let (addr, len) = sockaddr_un(path.as_ref())?;
 
-            cvt(libc::bind(socket.as_raw_fd(), &addr as *const _ as *const _, len as _))?;
+            cvt(libc::bind(socket.as_raw_fd(), core::ptr::addr_of!(addr) as *const _, len as _))?;
 
             Ok(socket)
         }
@@ -124,7 +124,7 @@ impl UnixDatagram {
             let socket = UnixDatagram::unbound()?;
             cvt(libc::bind(
                 socket.as_raw_fd(),
-                &socket_addr.addr as *const _ as *const _,
+                core::ptr::addr_of!(socket_addr.addr) as *const _,
                 socket_addr.len as _,
             ))?;
             Ok(socket)
@@ -206,7 +206,7 @@ impl UnixDatagram {
         unsafe {
             let (addr, len) = sockaddr_un(path.as_ref())?;
 
-            cvt(libc::connect(self.as_raw_fd(), &addr as *const _ as *const _, len))?;
+            cvt(libc::connect(self.as_raw_fd(), core::ptr::addr_of!(addr) as *const _, len))?;
         }
         Ok(())
     }
@@ -238,7 +238,7 @@ impl UnixDatagram {
         unsafe {
             cvt(libc::connect(
                 self.as_raw_fd(),
-                &socket_addr.addr as *const _ as *const _,
+                core::ptr::addr_of!(socket_addr.addr) as *const _,
                 socket_addr.len,
             ))?;
         }
@@ -505,7 +505,7 @@ impl UnixDatagram {
                 buf.as_ptr() as *const _,
                 buf.len(),
                 MSG_NOSIGNAL,
-                &addr as *const _ as *const _,
+                core::ptr::addr_of!(addr) as *const _,
                 len,
             ))?;
             Ok(count as usize)
@@ -540,7 +540,7 @@ impl UnixDatagram {
                 buf.as_ptr() as *const _,
                 buf.len(),
                 MSG_NOSIGNAL,
-                &socket_addr.addr as *const _ as *const _,
+                core::ptr::addr_of!(socket_addr.addr) as *const _,
                 socket_addr.len,
             ))?;
             Ok(count as usize)

std/src/os/unix/net/listener.rs

@@ -99,7 +99,11 @@ impl UnixListener {
             )))]
             const backlog: libc::c_int = libc::SOMAXCONN;
 
-            cvt(libc::bind(inner.as_inner().as_raw_fd(), &addr as *const _ as *const _, len as _))?;
+            cvt(libc::bind(
+                inner.as_inner().as_raw_fd(),
+                core::ptr::addr_of!(addr) as *const _,
+                len as _,
+            ))?;
             cvt(libc::listen(inner.as_inner().as_raw_fd(), backlog))?;
 
             Ok(UnixListener(inner))
@@ -139,7 +143,7 @@ impl UnixListener {
             const backlog: libc::c_int = 128;
             cvt(libc::bind(
                 inner.as_raw_fd(),
-                &socket_addr.addr as *const _ as *const _,
+                core::ptr::addr_of!(socket_addr.addr) as *const _,
                 socket_addr.len as _,
             ))?;
             cvt(libc::listen(inner.as_raw_fd(), backlog))?;
@@ -174,7 +178,7 @@ impl UnixListener {
     pub fn accept(&self) -> io::Result<(UnixStream, SocketAddr)> {
         let mut storage: libc::sockaddr_un = unsafe { mem::zeroed() };
         let mut len = mem::size_of_val(&storage) as libc::socklen_t;
-        let sock = self.0.accept(&mut storage as *mut _ as *mut _, &mut len)?;
+        let sock = self.0.accept(core::ptr::addr_of_mut!(storage) as *mut _, &mut len)?;
         let addr = SocketAddr::from_parts(storage, len)?;
         Ok((UnixStream(sock), addr))
     }

std/src/os/unix/net/stream.rs

@@ -96,7 +96,7 @@ impl UnixStream {
             let inner = Socket::new_raw(libc::AF_UNIX, libc::SOCK_STREAM)?;
             let (addr, len) = sockaddr_un(path.as_ref())?;
 
-            cvt(libc::connect(inner.as_raw_fd(), &addr as *const _ as *const _, len))?;
+            cvt(libc::connect(inner.as_raw_fd(), core::ptr::addr_of!(addr) as *const _, len))?;
             Ok(UnixStream(inner))
         }
     }
@@ -130,7 +130,7 @@ impl UnixStream {
             let inner = Socket::new_raw(libc::AF_UNIX, libc::SOCK_STREAM)?;
             cvt(libc::connect(
                 inner.as_raw_fd(),
-                &socket_addr.addr as *const _ as *const _,
+                core::ptr::addr_of!(socket_addr.addr) as *const _,
                 socket_addr.len,
             ))?;
             Ok(UnixStream(inner))

std/src/os/unix/ucred.rs

@@ -62,7 +62,7 @@ pub mod impl_linux {
                 socket.as_raw_fd(),
                 SOL_SOCKET,
                 SO_PEERCRED,
-                &mut ucred as *mut ucred as *mut c_void,
+                core::ptr::addr_of_mut!(ucred) as *mut c_void,
                 &mut ucred_size,
             );
 
@@ -122,7 +122,7 @@ pub mod impl_mac {
                 socket.as_raw_fd(),
                 SOL_LOCAL,
                 LOCAL_PEERPID,
-                &mut pid as *mut pid_t as *mut c_void,
+                core::ptr::addr_of_mut!(pid) as *mut c_void,
                 &mut pid_size,
             );
 

std/src/panicking.rs

@@ -502,7 +502,7 @@ pub unsafe fn r#try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>>
     // method of calling a catch panic whilst juggling ownership.
     let mut data = Data { f: ManuallyDrop::new(f) };
 
-    let data_ptr = &mut data as *mut _ as *mut u8;
+    let data_ptr = core::ptr::addr_of_mut!(data) as *mut u8;
     // SAFETY:
     //
     // Access to the union's fields: this is `std` and we know that the `r#try`

std/src/sync/mpmc/zero.rs

@@ -182,7 +182,11 @@ impl<T> Channel<T> {
             // Prepare for blocking until a receiver wakes us up.
             let oper = Operation::hook(token);
             let mut packet = Packet::<T>::message_on_stack(msg);
-            inner.senders.register_with_packet(oper, &mut packet as *mut Packet<T> as *mut (), cx);
+            inner.senders.register_with_packet(
+                oper,
+                core::ptr::addr_of_mut!(packet) as *mut (),
+                cx,
+            );
             inner.receivers.notify();
             drop(inner);
 
@@ -251,7 +255,7 @@ impl<T> Channel<T> {
             let mut packet = Packet::<T>::empty_on_stack();
             inner.receivers.register_with_packet(
                 oper,
-                &mut packet as *mut Packet<T> as *mut (),
+                core::ptr::addr_of_mut!(packet) as *mut (),
                 cx,
             );
             inner.senders.notify();

std/src/sys/pal/hermit/net.rs

@@ -207,7 +207,7 @@ impl Socket {
                 buf.as_mut_ptr(),
                 buf.len(),
                 flags,
-                &mut storage as *mut _ as *mut _,
+                core::ptr::addr_of_mut!(storage) as *mut _,
                 &mut addrlen,
             )
         })?;
@@ -323,7 +323,7 @@ impl Socket {
             netc::ioctl(
                 self.as_raw_fd(),
                 netc::FIONBIO,
-                &mut nonblocking as *mut _ as *mut core::ffi::c_void,
+                core::ptr::addr_of_mut!(nonblocking) as *mut core::ffi::c_void,
             )
         })
         .map(drop)

std/src/sys/pal/hermit/time.rs

@@ -100,7 +100,7 @@ pub struct Instant(Timespec);
 impl Instant {
     pub fn now() -> Instant {
         let mut time: Timespec = Timespec::zero();
-        let _ = unsafe { abi::clock_gettime(CLOCK_MONOTONIC, &mut time.t as *mut timespec) };
+        let _ = unsafe { abi::clock_gettime(CLOCK_MONOTONIC, core::ptr::addr_of_mut!(time.t)) };
 
         Instant(time)
     }
@@ -197,7 +197,7 @@ pub const UNIX_EPOCH: SystemTime = SystemTime(Timespec::zero());
 impl SystemTime {
     pub fn now() -> SystemTime {
         let mut time: Timespec = Timespec::zero();
-        let _ = unsafe { abi::clock_gettime(CLOCK_REALTIME, &mut time.t as *mut timespec) };
+        let _ = unsafe { abi::clock_gettime(CLOCK_REALTIME, core::ptr::addr_of_mut!(time.t)) };
 
         SystemTime(time)
     }

std/src/sys/pal/sgx/abi/tls/mod.rs

@@ -95,7 +95,7 @@ impl Tls {
     #[allow(unused)]
     pub unsafe fn activate_persistent(self: Box<Self>) {
         // FIXME: Needs safety information. See entry.S for `set_tls_ptr` definition.
-        unsafe { set_tls_ptr((&*self) as *const Tls as _) };
+        unsafe { set_tls_ptr(core::ptr::addr_of!(*self) as _) };
         mem::forget(self);
     }