Merge from rustc

Author: RalfJung

alloc/src/collections/btree/map.rs

@@ -3079,8 +3079,8 @@ impl<'a, K, V, A> CursorMut<'a, K, V, A> {
                 unsafe { self.root.reborrow() }
                     .as_mut()?
                     .borrow_mut()
-                    .first_leaf_edge()
-                    .next_kv()
+                    .last_leaf_edge()
+                    .next_back_kv()
                     .ok()?
                     .into_kv_valmut()
             }

alloc/src/collections/btree/map/tests.rs

@@ -8,6 +8,7 @@ use crate::testing::crash_test::{CrashTestDummy, Panic};
 use crate::testing::ord_chaos::{Cyclic3, Governed, Governor};
 use crate::testing::rng::DeterministicRng;
 use crate::vec::Vec;
+use core::assert_matches::assert_matches;
 use std::cmp::Ordering;
 use std::iter;
 use std::mem;
@@ -2448,3 +2449,21 @@ fn test_cursor_mut_insert_after_4() {
     let mut cur = map.upper_bound_mut(Bound::Included(&2));
     cur.insert_after(4, 'd');
 }
+
+#[test]
+fn cursor_peek_prev_agrees_with_cursor_mut() {
+    let mut map = BTreeMap::from([(1, 1), (2, 2), (3, 3)]);
+
+    let cursor = map.lower_bound(Bound::Excluded(&3));
+    assert!(cursor.key().is_none());
+
+    let prev = cursor.peek_prev();
+    assert_matches!(prev, Some((&3, _)));
+
+    // Shadow names so the two parts of this test match.
+    let mut cursor = map.lower_bound_mut(Bound::Excluded(&3));
+    assert!(cursor.key().is_none());
+
+    let prev = cursor.peek_prev();
+    assert_matches!(prev, Some((&3, _)));
+}

core/src/array/ascii.rs

@@ -4,10 +4,23 @@ use crate::ascii;
 impl<const N: usize> [u8; N] {
     /// Converts this array of bytes into a array of ASCII characters,
     /// or returns `None` if any of the characters is non-ASCII.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(ascii_char)]
+    /// #![feature(const_option)]
+    ///
+    /// const HEX_DIGITS: [std::ascii::Char; 16] =
+    ///     *b"0123456789abcdef".as_ascii().unwrap();
+    ///
+    /// assert_eq!(HEX_DIGITS[1].as_str(), "1");
+    /// assert_eq!(HEX_DIGITS[10].as_str(), "a");
+    /// ```
     #[unstable(feature = "ascii_char", issue = "110998")]
     #[must_use]
     #[inline]
-    pub fn as_ascii(&self) -> Option<&[ascii::Char; N]> {
+    pub const fn as_ascii(&self) -> Option<&[ascii::Char; N]> {
         if self.is_ascii() {
             // SAFETY: Just checked that it's ASCII
             Some(unsafe { self.as_ascii_unchecked() })

core/src/ffi/c_str.rs

@@ -79,9 +79,9 @@ use crate::str;
 ///
 /// [str]: prim@str "str"
 #[derive(Hash)]
-#[cfg_attr(not(test), rustc_diagnostic_item = "CStr")]
 #[stable(feature = "core_c_str", since = "1.64.0")]
 #[rustc_has_incoherent_inherent_impls]
+#[cfg_attr(not(bootstrap), lang = "CStr")]
 // FIXME:
 // `fn from` in `impl From<&CStr> for Box<CStr>` current implementation relies
 // on `CStr` being layout-compatible with `[u8]`.

core/src/iter/adapters/flatten.rs

@@ -310,6 +310,7 @@ where
 /// Real logic of both `Flatten` and `FlatMap` which simply delegate to
 /// this type.
 #[derive(Clone, Debug)]
+#[unstable(feature = "trusted_len", issue = "37572")]
 struct FlattenCompat<I, U> {
     iter: Fuse<I>,
     frontiter: Option<U>,
@@ -463,6 +464,7 @@ where
     }
 }
 
+#[unstable(feature = "trusted_len", issue = "37572")]
 impl<I, U> Iterator for FlattenCompat<I, U>
 where
     I: Iterator<Item: IntoIterator<IntoIter = U, Item = U::Item>>,
@@ -577,6 +579,7 @@ where
     }
 }
 
+#[unstable(feature = "trusted_len", issue = "37572")]
 impl<I, U> DoubleEndedIterator for FlattenCompat<I, U>
 where
     I: DoubleEndedIterator<Item: IntoIterator<IntoIter = U, Item = U::Item>>,
@@ -646,20 +649,23 @@ where
     }
 }
 
+#[unstable(feature = "trusted_len", issue = "37572")]
 unsafe impl<const N: usize, I, T> TrustedLen
     for FlattenCompat<I, <[T; N] as IntoIterator>::IntoIter>
 where
     I: TrustedLen<Item = [T; N]>,
 {
 }
 
+#[unstable(feature = "trusted_len", issue = "37572")]
 unsafe impl<'a, const N: usize, I, T> TrustedLen
     for FlattenCompat<I, <&'a [T; N] as IntoIterator>::IntoIter>
 where
     I: TrustedLen<Item = &'a [T; N]>,
 {
 }
 
+#[unstable(feature = "trusted_len", issue = "37572")]
 unsafe impl<'a, const N: usize, I, T> TrustedLen
     for FlattenCompat<I, <&'a mut [T; N] as IntoIterator>::IntoIter>
 where

core/src/lib.rs

@@ -150,6 +150,7 @@
 #![feature(const_slice_from_raw_parts_mut)]
 #![feature(const_slice_from_ref)]
 #![feature(const_slice_index)]
+#![feature(const_slice_is_ascii)]
 #![feature(const_slice_ptr_len)]
 #![feature(const_slice_split_at_mut)]
 #![feature(const_str_from_utf8_unchecked_mut)]

core/src/mem/maybe_uninit.rs

@@ -1287,7 +1287,7 @@ impl<T, const N: usize> MaybeUninit<[T; N]> {
     #[inline]
     pub const fn transpose(self) -> [MaybeUninit<T>; N] {
         // SAFETY: T and MaybeUninit<T> have the same layout
-        unsafe { super::transmute_copy(&ManuallyDrop::new(self)) }
+        unsafe { intrinsics::transmute_unchecked(self) }
     }
 }
 
@@ -1307,6 +1307,6 @@ impl<T, const N: usize> [MaybeUninit<T>; N] {
     #[inline]
     pub const fn transpose(self) -> MaybeUninit<[T; N]> {
         // SAFETY: T and MaybeUninit<T> have the same layout
-        unsafe { super::transmute_copy(&ManuallyDrop::new(self)) }
+        unsafe { intrinsics::transmute_unchecked(self) }
     }
 }

core/src/net/socket_addr.rs

@@ -122,6 +122,7 @@ impl SocketAddr {
     #[stable(feature = "ip_addr", since = "1.7.0")]
     #[must_use]
     #[rustc_const_stable(feature = "const_socketaddr", since = "1.69.0")]
+    #[inline]
     pub const fn new(ip: IpAddr, port: u16) -> SocketAddr {
         match ip {
             IpAddr::V4(a) => SocketAddr::V4(SocketAddrV4::new(a, port)),
@@ -142,6 +143,7 @@ impl SocketAddr {
     #[must_use]
     #[stable(feature = "ip_addr", since = "1.7.0")]
     #[rustc_const_stable(feature = "const_socketaddr", since = "1.69.0")]
+    #[inline]
     pub const fn ip(&self) -> IpAddr {
         match *self {
             SocketAddr::V4(ref a) => IpAddr::V4(*a.ip()),
@@ -161,6 +163,7 @@ impl SocketAddr {
     /// assert_eq!(socket.ip(), IpAddr::V4(Ipv4Addr::new(10, 10, 0, 1)));
     /// ```
     #[stable(feature = "sockaddr_setters", since = "1.9.0")]
+    #[inline]
     pub fn set_ip(&mut self, new_ip: IpAddr) {
         // `match (*self, new_ip)` would have us mutate a copy of self only to throw it away.
         match (self, new_ip) {
@@ -183,6 +186,7 @@ impl SocketAddr {
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_socketaddr", since = "1.69.0")]
+    #[inline]
     pub const fn port(&self) -> u16 {
         match *self {
             SocketAddr::V4(ref a) => a.port(),
@@ -202,6 +206,7 @@ impl SocketAddr {
     /// assert_eq!(socket.port(), 1025);
     /// ```
     #[stable(feature = "sockaddr_setters", since = "1.9.0")]
+    #[inline]
     pub fn set_port(&mut self, new_port: u16) {
         match *self {
             SocketAddr::V4(ref mut a) => a.set_port(new_port),
@@ -227,6 +232,7 @@ impl SocketAddr {
     #[must_use]
     #[stable(feature = "sockaddr_checker", since = "1.16.0")]
     #[rustc_const_stable(feature = "const_socketaddr", since = "1.69.0")]
+    #[inline]
     pub const fn is_ipv4(&self) -> bool {
         matches!(*self, SocketAddr::V4(_))
     }
@@ -249,6 +255,7 @@ impl SocketAddr {
     #[must_use]
     #[stable(feature = "sockaddr_checker", since = "1.16.0")]
     #[rustc_const_stable(feature = "const_socketaddr", since = "1.69.0")]
+    #[inline]
     pub const fn is_ipv6(&self) -> bool {
         matches!(*self, SocketAddr::V6(_))
     }
@@ -269,6 +276,7 @@ impl SocketAddrV4 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use]
     #[rustc_const_stable(feature = "const_socketaddr", since = "1.69.0")]
+    #[inline]
     pub const fn new(ip: Ipv4Addr, port: u16) -> SocketAddrV4 {
         SocketAddrV4 { ip, port }
     }
@@ -286,6 +294,7 @@ impl SocketAddrV4 {
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_socketaddr", since = "1.69.0")]
+    #[inline]
     pub const fn ip(&self) -> &Ipv4Addr {
         &self.ip
     }
@@ -302,6 +311,7 @@ impl SocketAddrV4 {
     /// assert_eq!(socket.ip(), &Ipv4Addr::new(192, 168, 0, 1));
     /// ```
     #[stable(feature = "sockaddr_setters", since = "1.9.0")]
+    #[inline]
     pub fn set_ip(&mut self, new_ip: Ipv4Addr) {
         self.ip = new_ip;
     }
@@ -319,6 +329,7 @@ impl SocketAddrV4 {
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_socketaddr", since = "1.69.0")]
+    #[inline]
     pub const fn port(&self) -> u16 {
         self.port
     }
@@ -335,6 +346,7 @@ impl SocketAddrV4 {
     /// assert_eq!(socket.port(), 4242);
     /// ```
     #[stable(feature = "sockaddr_setters", since = "1.9.0")]
+    #[inline]
     pub fn set_port(&mut self, new_port: u16) {
         self.port = new_port;
     }
@@ -360,6 +372,7 @@ impl SocketAddrV6 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use]
     #[rustc_const_stable(feature = "const_socketaddr", since = "1.69.0")]
+    #[inline]
     pub const fn new(ip: Ipv6Addr, port: u16, flowinfo: u32, scope_id: u32) -> SocketAddrV6 {
         SocketAddrV6 { ip, port, flowinfo, scope_id }
     }
@@ -377,6 +390,7 @@ impl SocketAddrV6 {
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_socketaddr", since = "1.69.0")]
+    #[inline]
     pub const fn ip(&self) -> &Ipv6Addr {
         &self.ip
     }
@@ -393,6 +407,7 @@ impl SocketAddrV6 {
     /// assert_eq!(socket.ip(), &Ipv6Addr::new(76, 45, 0, 0, 0, 0, 0, 0));
     /// ```
     #[stable(feature = "sockaddr_setters", since = "1.9.0")]
+    #[inline]
     pub fn set_ip(&mut self, new_ip: Ipv6Addr) {
         self.ip = new_ip;
     }
@@ -410,6 +425,7 @@ impl SocketAddrV6 {
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_socketaddr", since = "1.69.0")]
+    #[inline]
     pub const fn port(&self) -> u16 {
         self.port
     }
@@ -426,6 +442,7 @@ impl SocketAddrV6 {
     /// assert_eq!(socket.port(), 4242);
     /// ```
     #[stable(feature = "sockaddr_setters", since = "1.9.0")]
+    #[inline]
     pub fn set_port(&mut self, new_port: u16) {
         self.port = new_port;
     }
@@ -453,6 +470,7 @@ impl SocketAddrV6 {
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_socketaddr", since = "1.69.0")]
+    #[inline]
     pub const fn flowinfo(&self) -> u32 {
         self.flowinfo
     }
@@ -471,6 +489,7 @@ impl SocketAddrV6 {
     /// assert_eq!(socket.flowinfo(), 56);
     /// ```
     #[stable(feature = "sockaddr_setters", since = "1.9.0")]
+    #[inline]
     pub fn set_flowinfo(&mut self, new_flowinfo: u32) {
         self.flowinfo = new_flowinfo;
     }
@@ -493,6 +512,7 @@ impl SocketAddrV6 {
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_socketaddr", since = "1.69.0")]
+    #[inline]
     pub const fn scope_id(&self) -> u32 {
         self.scope_id
     }
@@ -511,6 +531,7 @@ impl SocketAddrV6 {
     /// assert_eq!(socket.scope_id(), 42);
     /// ```
     #[stable(feature = "sockaddr_setters", since = "1.9.0")]
+    #[inline]
     pub fn set_scope_id(&mut self, new_scope_id: u32) {
         self.scope_id = new_scope_id;
     }
@@ -519,6 +540,7 @@ impl SocketAddrV6 {
 #[stable(feature = "ip_from_ip", since = "1.16.0")]
 impl From<SocketAddrV4> for SocketAddr {
     /// Converts a [`SocketAddrV4`] into a [`SocketAddr::V4`].
+    #[inline]
     fn from(sock4: SocketAddrV4) -> SocketAddr {
         SocketAddr::V4(sock4)
     }
@@ -527,6 +549,7 @@ impl From<SocketAddrV4> for SocketAddr {
 #[stable(feature = "ip_from_ip", since = "1.16.0")]
 impl From<SocketAddrV6> for SocketAddr {
     /// Converts a [`SocketAddrV6`] into a [`SocketAddr::V6`].
+    #[inline]
     fn from(sock6: SocketAddrV6) -> SocketAddr {
         SocketAddr::V6(sock6)
     }
@@ -624,27 +647,31 @@ impl fmt::Debug for SocketAddrV6 {
 
 #[stable(feature = "socketaddr_ordering", since = "1.45.0")]
 impl PartialOrd for SocketAddrV4 {
+    #[inline]
     fn partial_cmp(&self, other: &SocketAddrV4) -> Option<Ordering> {
         Some(self.cmp(other))
     }
 }
 
 #[stable(feature = "socketaddr_ordering", since = "1.45.0")]
 impl PartialOrd for SocketAddrV6 {
+    #[inline]
     fn partial_cmp(&self, other: &SocketAddrV6) -> Option<Ordering> {
         Some(self.cmp(other))
     }
 }
 
 #[stable(feature = "socketaddr_ordering", since = "1.45.0")]
 impl Ord for SocketAddrV4 {
+    #[inline]
     fn cmp(&self, other: &SocketAddrV4) -> Ordering {
         self.ip().cmp(other.ip()).then(self.port().cmp(&other.port()))
     }
 }
 
 #[stable(feature = "socketaddr_ordering", since = "1.45.0")]
 impl Ord for SocketAddrV6 {
+    #[inline]
     fn cmp(&self, other: &SocketAddrV6) -> Ordering {
         self.ip().cmp(other.ip()).then(self.port().cmp(&other.port()))
     }

core/src/option.rs

@@ -1641,10 +1641,8 @@ impl<T> Option<T> {
     where
         F: FnOnce() -> T,
     {
-        if let None = *self {
-            // the compiler isn't smart enough to know that we are not dropping a `T`
-            // here and wants us to ensure `T` can be dropped at compile time.
-            mem::forget(mem::replace(self, Some(f())))
+        if let None = self {
+            *self = Some(f());
         }
 
         // SAFETY: a `None` variant for `self` would have been replaced by a `Some`