Auto merge of #88556 - m-ou-se:rollup-q636wyd, r=m-ou-se

Rollup of 9 pull requests

Successful merges:

 - #86376 (Emit specific warning to clarify that `#[no_mangle]` should not be applied on foreign statics or functions)
 - #88040 (BTree: remove Ord bound from new)
 - #88053 (Fix the flock fallback implementation)
 - #88350 (add support for clobbering xer, cr, and cr[0-7] for asm! on OpenPower/PowerPC)
 - #88410 (Remove bolding on associated constants)
 - #88525 (fix(rustc_typeck): produce better errors for dyn auto trait)
 - #88542 (Use the return value of readdir_r() instead of errno)
 - #88548 (Stabilize `Iterator::intersperse()`)
 - #88551 (Stabilize `UnsafeCell::raw_get()`)

Failed merges:

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

33 files changed, 401 insertions, 81 deletions

diff --git a/compiler/rustc_codegen_llvm/src/asm.rs b/compiler/rustc_codegen_llvm/src/asm.rs
index 1689fdd4f2e..e0d312727a5 100644
--- a/compiler/rustc_codegen_llvm/src/asm.rs
+++ b/compiler/rustc_codegen_llvm/src/asm.rs
@@ -616,6 +616,10 @@ fn reg_to_llvm(reg: InlineAsmRegOrRegClass, layout: Option<&TyAndLayout<'tcx>>)
             InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::reg) => "r",
             InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::reg_nonzero) => "b",
             InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::freg) => "f",
+            InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::cr)
+            | InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::xer) => {
+                unreachable!("clobber-only")
+            }
             InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::reg) => "r",
             InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::freg) => "f",
             InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::vreg) => {
@@ -755,6 +759,10 @@ fn dummy_output_type(cx: &CodegenCx<'ll, 'tcx>, reg: InlineAsmRegClass) -> &'ll
         InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::reg) => cx.type_i32(),
         InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::reg_nonzero) => cx.type_i32(),
         InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::freg) => cx.type_f64(),
+        InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::cr)
+        | InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::xer) => {
+            unreachable!("clobber-only")
+        }
         InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::reg) => cx.type_i32(),
         InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::freg) => cx.type_f32(),
         InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::vreg) => {
diff --git a/compiler/rustc_data_structures/src/flock.rs b/compiler/rustc_data_structures/src/flock.rs
index 4f5d8d7ea48..293ef4caac4 100644
--- a/compiler/rustc_data_structures/src/flock.rs
+++ b/compiler/rustc_data_structures/src/flock.rs
@@ -222,6 +222,10 @@ cfg_if! {
                 let msg = "file locks not supported on this platform";
                 Err(io::Error::new(io::ErrorKind::Other, msg))
             }
+
+            pub fn error_unsupported(_err: &io::Error) -> bool {
+                true
+            }
         }
     }
 }
diff --git a/compiler/rustc_error_codes/src/error_codes.rs b/compiler/rustc_error_codes/src/error_codes.rs
index c2e62328cb1..45d91c2047d 100644
--- a/compiler/rustc_error_codes/src/error_codes.rs
+++ b/compiler/rustc_error_codes/src/error_codes.rs
@@ -480,6 +480,7 @@ E0781: include_str!("./error_codes/E0781.md"),
 E0782: include_str!("./error_codes/E0782.md"),
 E0783: include_str!("./error_codes/E0783.md"),
 E0784: include_str!("./error_codes/E0784.md"),
+E0785: include_str!("./error_codes/E0785.md"),
 ;
 //  E0006, // merged with E0005
 //  E0008, // cannot bind by-move into a pattern guard
diff --git a/compiler/rustc_error_codes/src/error_codes/E0785.md b/compiler/rustc_error_codes/src/error_codes/E0785.md
new file mode 100644
index 00000000000..373320539ef
--- /dev/null
+++ b/compiler/rustc_error_codes/src/error_codes/E0785.md
@@ -0,0 +1,30 @@
+An inherent `impl` was written on a dyn auto trait.
+
+Erroneous code example:
+
+```compile_fail,E0785
+#![feature(auto_traits)]
+
+auto trait AutoTrait {}
+
+impl dyn AutoTrait {}
+```
+
+Dyn objects allow any number of auto traits, plus at most one non-auto trait.
+The non-auto trait becomes the "principal trait".
+
+When checking if an impl on a dyn trait is coherent, the principal trait is
+normally the only one considered. Since the erroneous code has no principal
+trait, it cannot be implemented at all.
+
+Working example:
+
+```
+#![feature(auto_traits)]
+
+trait PrincipalTrait {}
+
+auto trait AutoTrait {}
+
+impl dyn PrincipalTrait + AutoTrait + Send {}
+```
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index d3dac35d2c9..fd438bdc900 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -1331,6 +1331,36 @@ impl CheckAttrVisitor<'tcx> {
             Target::Field | Target::Arm | Target::MacroDef => {
                 self.inline_attr_str_error_with_macro_def(hir_id, attr, "no_mangle");
             }
+            // FIXME: #[no_mangle] was previously allowed on non-functions/statics, this should be an error
+            // The error should specify that the item that is wrong is specifically a *foreign* fn/static
+            // otherwise the error seems odd
+            Target::ForeignFn | Target::ForeignStatic => {
+                let foreign_item_kind = match target {
+                    Target::ForeignFn => "function",
+                    Target::ForeignStatic => "static",
+                    _ => unreachable!(),
+                };
+                self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
+                    lint.build(&format!(
+                        "`#[no_mangle]` has no effect on a foreign {}",
+                        foreign_item_kind
+                    ))
+                    .warn(
+                        "this was previously accepted by the compiler but is \
+                            being phased out; it will become a hard error in \
+                            a future release!",
+                    )
+                    .span_label(*span, format!("foreign {}", foreign_item_kind))
+                    .note("symbol names in extern blocks are not mangled")
+                    .span_suggestion(
+                        attr.span,
+                        "remove this attribute",
+                        String::new(),
+                        Applicability::MachineApplicable,
+                    )
+                    .emit();
+                });
+            }
             _ => {
                 // FIXME: #[no_mangle] was previously allowed on non-functions/statics and some
                 // crates used this, so only emit a warning.
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 899c51e12ff..24023163cc3 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -479,6 +479,7 @@ symbols! {
         core_panic_macro,
         cosf32,
         cosf64,
+        cr,
         crate_id,
         crate_in_paths,
         crate_local,
@@ -1418,6 +1419,7 @@ symbols! {
         wreg,
         write_bytes,
         x87_reg,
+        xer,
         xmm_reg,
         ymm_reg,
         zmm_reg,
diff --git a/compiler/rustc_target/src/asm/mod.rs b/compiler/rustc_target/src/asm/mod.rs
index fb23e5c85a1..99699c50df5 100644
--- a/compiler/rustc_target/src/asm/mod.rs
+++ b/compiler/rustc_target/src/asm/mod.rs
@@ -355,7 +355,7 @@ impl InlineAsmReg {
             Self::Arm(r) => r.overlapping_regs(|r| cb(Self::Arm(r))),
             Self::AArch64(_) => cb(self),
             Self::RiscV(_) => cb(self),
-            Self::PowerPC(_) => cb(self),
+            Self::PowerPC(r) => r.overlapping_regs(|r| cb(Self::PowerPC(r))),
             Self::Hexagon(r) => r.overlapping_regs(|r| cb(Self::Hexagon(r))),
             Self::Mips(_) => cb(self),
             Self::S390x(_) => cb(self),
diff --git a/compiler/rustc_target/src/asm/powerpc.rs b/compiler/rustc_target/src/asm/powerpc.rs
index 42fc25c4ff5..51a4303689e 100644
--- a/compiler/rustc_target/src/asm/powerpc.rs
+++ b/compiler/rustc_target/src/asm/powerpc.rs
@@ -7,6 +7,8 @@ def_reg_class! {
         reg,
         reg_nonzero,
         freg,
+        cr,
+        xer,
     }
 }
 
@@ -44,6 +46,7 @@ impl PowerPCInlineAsmRegClass {
                 }
             }
             Self::freg => types! { _: F32, F64; },
+            Self::cr | Self::xer => &[],
         }
     }
 }
@@ -108,6 +111,16 @@ def_regs! {
         f29: freg = ["f29", "fr29"],
         f30: freg = ["f30", "fr30"],
         f31: freg = ["f31", "fr31"],
+        cr: cr = ["cr"],
+        cr0: cr = ["cr0"],
+        cr1: cr = ["cr1"],
+        cr2: cr = ["cr2"],
+        cr3: cr = ["cr3"],
+        cr4: cr = ["cr4"],
+        cr5: cr = ["cr5"],
+        cr6: cr = ["cr6"],
+        cr7: cr = ["cr7"],
+        xer: xer = ["xer"],
         #error = ["r1", "1", "sp"] =>
             "the stack pointer cannot be used as an operand for inline asm",
         #error = ["r2", "2"] =>
@@ -136,17 +149,55 @@ impl PowerPCInlineAsmReg {
         _arch: InlineAsmArch,
         _modifier: Option<char>,
     ) -> fmt::Result {
+        macro_rules! do_emit {
+            (
+                $($(($reg:ident, $value:literal)),*;)*
+            ) => {
+                out.write_str(match self {
+                    $($(Self::$reg => $value,)*)*
+                })
+            };
+        }
         // Strip off the leading prefix.
-        if self as u32 <= Self::r28 as u32 {
-            let index = self as u32 - Self::r28 as u32;
-            write!(out, "{}", index)
-        } else if self as u32 >= Self::f0 as u32 && self as u32 <= Self::f31 as u32 {
-            let index = self as u32 - Self::f31 as u32;
-            write!(out, "{}", index)
-        } else {
-            unreachable!()
+        do_emit! {
+            (r0, "0"), (r3, "3"), (r4, "4"), (r5, "5"), (r6, "6"), (r7, "7");
+            (r8, "8"), (r9, "9"), (r10, "10"), (r11, "11"), (r12, "12"), (r14, "14"), (r15, "15");
+            (r16, "16"), (r17, "17"), (r18, "18"), (r19, "19"), (r20, "20"), (r21, "21"), (r22, "22"), (r23, "23");
+            (r24, "24"), (r25, "25"), (r26, "26"), (r27, "27"), (r28, "28");
+            (f0, "0"), (f1, "1"), (f2, "2"), (f3, "3"), (f4, "4"), (f5, "5"), (f6, "6"), (f7, "7");
+            (f8, "8"), (f9, "9"), (f10, "10"), (f11, "11"), (f12, "12"), (f13, "13"), (f14, "14"), (f15, "15");
+            (f16, "16"), (f17, "17"), (f18, "18"), (f19, "19"), (f20, "20"), (f21, "21"), (f22, "22"), (f23, "23");
+            (f24, "24"), (f25, "25"), (f26, "26"), (f27, "27"), (f28, "28"), (f29, "29"), (f30, "30"), (f31, "31");
+            (cr, "cr");
+            (cr0, "0"), (cr1, "1"), (cr2, "2"), (cr3, "3"), (cr4, "4"), (cr5, "5"), (cr6, "6"), (cr7, "7");
+            (xer, "xer");
         }
     }
 
-    pub fn overlapping_regs(self, mut _cb: impl FnMut(PowerPCInlineAsmReg)) {}
+    pub fn overlapping_regs(self, mut cb: impl FnMut(PowerPCInlineAsmReg)) {
+        macro_rules! reg_conflicts {
+            (
+                $(
+                    $full:ident : $($field:ident)*
+                ),*;
+            ) => {
+                match self {
+                    $(
+                        Self::$full => {
+                            cb(Self::$full);
+                            $(cb(Self::$field);)*
+                        }
+                        $(Self::$field)|* => {
+                            cb(Self::$full);
+                            cb(self);
+                        }
+                    )*
+                    r => cb(r),
+                }
+            };
+        }
+        reg_conflicts! {
+            cr : cr0 cr1 cr2 cr3 cr4 cr5 cr6 cr7;
+        }
+    }
 }
diff --git a/compiler/rustc_typeck/src/coherence/inherent_impls.rs b/compiler/rustc_typeck/src/coherence/inherent_impls.rs
index 51698437a30..c7be9e21235 100644
--- a/compiler/rustc_typeck/src/coherence/inherent_impls.rs
+++ b/compiler/rustc_typeck/src/coherence/inherent_impls.rs
@@ -60,6 +60,17 @@ impl ItemLikeVisitor<'v> for InherentCollect<'tcx> {
             ty::Dynamic(ref data, ..) if data.principal_def_id().is_some() => {
                 self.check_def_id(item, data.principal_def_id().unwrap());
             }
+            ty::Dynamic(..) => {
+                struct_span_err!(
+                    self.tcx.sess,
+                    ty.span,
+                    E0785,
+                    "cannot define inherent `impl` for a dyn auto trait"
+                )
+                .span_label(ty.span, "impl requires at least one non-auto trait")
+                .note("define and implement a new trait or type instead")
+                .emit();
+            }
             ty::Bool => {
                 self.check_primitive_impl(
                     item.def_id,
diff --git a/library/alloc/src/collections/btree/map.rs b/library/alloc/src/collections/btree/map.rs
index 4b649e43371..70a838a35f9 100644
--- a/library/alloc/src/collections/btree/map.rs
+++ b/library/alloc/src/collections/btree/map.rs
@@ -233,9 +233,7 @@ impl<K: Clone, V: Clone> Clone for BTreeMap<K, V> {
         }
 
         if self.is_empty() {
-            // Ideally we'd call `BTreeMap::new` here, but that has the `K:
-            // Ord` constraint, which this method lacks.
-            BTreeMap { root: None, length: 0 }
+            BTreeMap::new()
         } else {
             clone_subtree(self.root.as_ref().unwrap().reborrow()) // unwrap succeeds because not empty
         }
@@ -499,10 +497,7 @@ impl<K, V> BTreeMap<K, V> {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_btree_new", issue = "71835")]
-    pub const fn new() -> BTreeMap<K, V>
-    where
-        K: Ord,
-    {
+    pub const fn new() -> BTreeMap<K, V> {
         BTreeMap { root: None, length: 0 }
     }
 
@@ -522,7 +517,7 @@ impl<K, V> BTreeMap<K, V> {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn clear(&mut self) {
-        *self = BTreeMap { root: None, length: 0 };
+        *self = BTreeMap::new();
     }
 
     /// Returns a reference to the value corresponding to the key.
@@ -1957,7 +1952,7 @@ impl<K: Hash, V: Hash> Hash for BTreeMap<K, V> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<K: Ord, V> Default for BTreeMap<K, V> {
+impl<K, V> Default for BTreeMap<K, V> {
     /// Creates an empty `BTreeMap`.
     fn default() -> BTreeMap<K, V> {
         BTreeMap::new()
diff --git a/library/alloc/src/collections/btree/map/tests.rs b/library/alloc/src/collections/btree/map/tests.rs
index 17e53848343..a99d6c49ab7 100644
--- a/library/alloc/src/collections/btree/map/tests.rs
+++ b/library/alloc/src/collections/btree/map/tests.rs
@@ -1745,7 +1745,7 @@ fn test_send() {
     }
 }
 
-#[allow(dead_code)]
+#[test]
 fn test_ord_absence() {
     fn map<K>(mut map: BTreeMap<K, ()>) {
         map.is_empty();
@@ -1784,6 +1784,12 @@ fn test_ord_absence() {
     fn map_clone<K: Clone>(mut map: BTreeMap<K, ()>) {
         map.clone_from(&map.clone());
     }
+
+    #[derive(Debug, Clone)]
+    struct NonOrd;
+    map(BTreeMap::<NonOrd, _>::new());
+    map_debug(BTreeMap::<NonOrd, _>::new());
+    map_clone(BTreeMap::<NonOrd, _>::default());
 }
 
 #[test]
diff --git a/library/alloc/src/collections/btree/set.rs b/library/alloc/src/collections/btree/set.rs
index 0c268ad32b2..ff0db22e0cc 100644
--- a/library/alloc/src/collections/btree/set.rs
+++ b/library/alloc/src/collections/btree/set.rs
@@ -246,10 +246,7 @@ impl<T> BTreeSet<T> {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_btree_new", issue = "71835")]
-    pub const fn new() -> BTreeSet<T>
-    where
-        T: Ord,
-    {
+    pub const fn new() -> BTreeSet<T> {
         BTreeSet { map: BTreeMap::new() }
     }
 
@@ -1192,7 +1189,7 @@ impl<'a, T: 'a + Ord + Copy> Extend<&'a T> for BTreeSet<T> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T: Ord> Default for BTreeSet<T> {
+impl<T> Default for BTreeSet<T> {
     /// Creates an empty `BTreeSet`.
     fn default() -> BTreeSet<T> {
         BTreeSet::new()
diff --git a/library/alloc/src/collections/btree/set/tests.rs b/library/alloc/src/collections/btree/set/tests.rs
index 5d590a26281..0a87ae12d61 100644
--- a/library/alloc/src/collections/btree/set/tests.rs
+++ b/library/alloc/src/collections/btree/set/tests.rs
@@ -607,7 +607,7 @@ fn test_send() {
     }
 }
 
-#[allow(dead_code)]
+#[test]
 fn test_ord_absence() {
     fn set<K>(mut set: BTreeSet<K>) {
         set.is_empty();
@@ -626,6 +626,12 @@ fn test_ord_absence() {
     fn set_clone<K: Clone>(mut set: BTreeSet<K>) {
         set.clone_from(&set.clone());
     }
+
+    #[derive(Debug, Clone)]
+    struct NonOrd;
+    set(BTreeSet::<NonOrd>::new());
+    set_debug(BTreeSet::<NonOrd>::new());
+    set_clone(BTreeSet::<NonOrd>::default());
 }
 
 #[test]
diff --git a/library/alloc/tests/const_fns.rs b/library/alloc/tests/const_fns.rs
index da58ae92e11..f448b3eb7c3 100644
--- a/library/alloc/tests/const_fns.rs
+++ b/library/alloc/tests/const_fns.rs
@@ -1,29 +1,5 @@
 // Test const functions in the library
 
-use core::cmp::Ordering;
-
-// FIXME remove this struct once we put `K: ?const Ord` on BTreeMap::new.
-#[derive(PartialEq, Eq, PartialOrd)]
-pub struct MyType;
-
-impl const Ord for MyType {
-    fn cmp(&self, _: &Self) -> Ordering {
-        Ordering::Equal
-    }
-
-    fn max(self, _: Self) -> Self {
-        Self
-    }
-
-    fn min(self, _: Self) -> Self {
-        Self
-    }
-
-    fn clamp(self, _: Self, _: Self) -> Self {
-        Self
-    }
-}
-
 pub const MY_VEC: Vec<usize> = Vec::new();
 pub const MY_VEC2: Vec<usize> = Default::default();
 
@@ -32,13 +8,13 @@ pub const MY_STRING2: String = Default::default();
 
 use std::collections::{BTreeMap, BTreeSet};
 
-pub const MY_BTREEMAP: BTreeMap<MyType, MyType> = BTreeMap::new();
-pub const MAP: &'static BTreeMap<MyType, MyType> = &MY_BTREEMAP;
+pub const MY_BTREEMAP: BTreeMap<usize, usize> = BTreeMap::new();
+pub const MAP: &'static BTreeMap<usize, usize> = &MY_BTREEMAP;
 pub const MAP_LEN: usize = MAP.len();
 pub const MAP_IS_EMPTY: bool = MAP.is_empty();
 
-pub const MY_BTREESET: BTreeSet<MyType> = BTreeSet::new();
-pub const SET: &'static BTreeSet<MyType> = &MY_BTREESET;
+pub const MY_BTREESET: BTreeSet<usize> = BTreeSet::new();
+pub const SET: &'static BTreeSet<usize> = &MY_BTREESET;
 pub const SET_LEN: usize = SET.len();
 pub const SET_IS_EMPTY: bool = SET.is_empty();
 
diff --git a/library/core/src/cell.rs b/library/core/src/cell.rs
index 85b43f48847..2adf6a549e6 100644
--- a/library/core/src/cell.rs
+++ b/library/core/src/cell.rs
@@ -1921,7 +1921,7 @@ impl<T: ?Sized> UnsafeCell<T> {
     }
 
     /// Gets a mutable pointer to the wrapped value.
-    /// The difference to [`get`] is that this function accepts a raw pointer,
+    /// The difference from [`get`] is that this function accepts a raw pointer,
     /// which is useful to avoid the creation of temporary references.
     ///
     /// The result can be cast to a pointer of any kind.
@@ -1937,7 +1937,6 @@ impl<T: ?Sized> UnsafeCell<T> {
     /// calling `get` would require creating a reference to uninitialized data:
     ///
     /// ```
-    /// #![feature(unsafe_cell_raw_get)]
     /// use std::cell::UnsafeCell;
     /// use std::mem::MaybeUninit;
     ///
@@ -1948,7 +1947,7 @@ impl<T: ?Sized> UnsafeCell<T> {
     /// assert_eq!(uc.into_inner(), 5);
     /// ```
     #[inline(always)]
-    #[unstable(feature = "unsafe_cell_raw_get", issue = "66358")]
+    #[stable(feature = "unsafe_cell_raw_get", since = "1.56.0")]
     pub const fn raw_get(this: *const Self) -> *mut T {
         // We can just cast the pointer from `UnsafeCell<T>` to `T` because of
         // #[repr(transparent)]. This exploits libstd's special status, there is
diff --git a/library/core/src/iter/adapters/intersperse.rs b/library/core/src/iter/adapters/intersperse.rs
index d8bbd424cf2..bd21872e1ad 100644
--- a/library/core/src/iter/adapters/intersperse.rs
+++ b/library/core/src/iter/adapters/intersperse.rs
@@ -4,7 +4,7 @@ use super::Peekable;
 ///
 /// This `struct` is created by [`Iterator::intersperse`]. See its documentation
 /// for more information.
-#[unstable(feature = "iter_intersperse", reason = "recently added", issue = "79524")]
+#[stable(feature = "iter_intersperse", since = "1.56.0")]
 #[derive(Debug, Clone)]
 pub struct Intersperse<I: Iterator>
 where
@@ -24,7 +24,7 @@ where
     }
 }
 
-#[unstable(feature = "iter_intersperse", reason = "recently added", issue = "79524")]
+#[stable(feature = "iter_intersperse", since = "1.56.0")]
 impl<I> Iterator for Intersperse<I>
 where
     I: Iterator,
@@ -61,7 +61,7 @@ where
 ///
 /// This `struct` is created by [`Iterator::intersperse_with`]. See its
 /// documentation for more information.
-#[unstable(feature = "iter_intersperse", reason = "recently added", issue = "79524")]
+#[stable(feature = "iter_intersperse", since = "1.56.0")]
 pub struct IntersperseWith<I, G>
 where
     I: Iterator,
@@ -71,7 +71,7 @@ where
     needs_sep: bool,
 }
 
-#[unstable(feature = "iter_intersperse", reason = "recently added", issue = "79524")]
+#[stable(feature = "iter_intersperse", since = "1.56.0")]
 impl<I, G> crate::fmt::Debug for IntersperseWith<I, G>
 where
     I: Iterator + crate::fmt::Debug,
@@ -87,7 +87,7 @@ where
     }
 }
 
-#[unstable(feature = "iter_intersperse", reason = "recently added", issue = "79524")]
+#[stable(feature = "iter_intersperse", since = "1.56.0")]
 impl<I, G> crate::clone::Clone for IntersperseWith<I, G>
 where
     I: Iterator + crate::clone::Clone,
@@ -113,7 +113,7 @@ where
     }
 }
 
-#[unstable(feature = "iter_intersperse", reason = "recently added", issue = "79524")]
+#[stable(feature = "iter_intersperse", since = "1.56.0")]
 impl<I, G> Iterator for IntersperseWith<I, G>
 where
     I: Iterator,
diff --git a/library/core/src/iter/adapters/mod.rs b/library/core/src/iter/adapters/mod.rs
index 056ccca1d01..f02d278aff5 100644
--- a/library/core/src/iter/adapters/mod.rs
+++ b/library/core/src/iter/adapters/mod.rs
@@ -42,7 +42,7 @@ pub use self::flatten::Flatten;
 #[stable(feature = "iter_copied", since = "1.36.0")]
 pub use self::copied::Copied;
 
-#[unstable(feature = "iter_intersperse", reason = "recently added", issue = "79524")]
+#[stable(feature = "iter_intersperse", since = "1.56.0")]
 pub use self::intersperse::{Intersperse, IntersperseWith};
 
 #[unstable(feature = "iter_map_while", reason = "recently added", issue = "68537")]
diff --git a/library/core/src/iter/mod.rs b/library/core/src/iter/mod.rs
index 7fb80f954ff..cd8a26025ff 100644
--- a/library/core/src/iter/mod.rs
+++ b/library/core/src/iter/mod.rs
@@ -414,7 +414,7 @@ pub use self::adapters::{
     Chain, Cycle, Enumerate, Filter, FilterMap, FlatMap, Fuse, Inspect, Map, Peekable, Rev, Scan,
     Skip, SkipWhile, Take, TakeWhile, Zip,
 };
-#[unstable(feature = "iter_intersperse", reason = "recently added", issue = "79524")]
+#[stable(feature = "iter_intersperse", since = "1.56.0")]
 pub use self::adapters::{Intersperse, IntersperseWith};
 
 pub(crate) use self::adapters::process_results;
diff --git a/library/core/src/iter/traits/iterator.rs b/library/core/src/iter/traits/iterator.rs
index 850435b53cc..330d3714247 100644
--- a/library/core/src/iter/traits/iterator.rs
+++ b/library/core/src/iter/traits/iterator.rs
@@ -535,8 +535,6 @@ pub trait Iterator {
     /// Basic usage:
     ///
     /// ```
-    /// #![feature(iter_intersperse)]
-    ///
     /// let mut a = [0, 1, 2].iter().intersperse(&100);
     /// assert_eq!(a.next(), Some(&0));   // The first element from `a`.
     /// assert_eq!(a.next(), Some(&100)); // The separator.
@@ -547,9 +545,8 @@ pub trait Iterator {
     /// ```
     ///
     /// `intersperse` can be very useful to join an iterator's items using a common element:
-    /// ```
-    /// #![feature(iter_intersperse)]
     ///
+    /// ```
     /// let hello = ["Hello", "World", "!"].iter().copied().intersperse(" ").collect::<String>();
     /// assert_eq!(hello, "Hello World !");
     /// ```
@@ -557,7 +554,7 @@ pub trait Iterator {
     /// [`Clone`]: crate::clone::Clone
     /// [`intersperse_with`]: Iterator::intersperse_with
     #[inline]
-    #[unstable(feature = "iter_intersperse", reason = "recently added", issue = "79524")]
+    #[stable(feature = "iter_intersperse", since = "1.56.0")]
     fn intersperse(self, separator: Self::Item) -> Intersperse<Self>
     where
         Self: Sized,
@@ -582,8 +579,6 @@ pub trait Iterator {
     /// Basic usage:
     ///
     /// ```
-    /// #![feature(iter_intersperse)]
-    ///
     /// #[derive(PartialEq, Debug)]
     /// struct NotClone(usize);
     ///
@@ -600,9 +595,8 @@ pub trait Iterator {
     ///
     /// `intersperse_with` can be used in situations where the separator needs
     /// to be computed:
-    /// ```
-    /// #![feature(iter_intersperse)]
     ///
+    /// ```
     /// let src = ["Hello", "to", "all", "people", "!!"].iter().copied();
     ///
     /// // The closure mutably borrows its context to generate an item.
@@ -615,7 +609,7 @@ pub trait Iterator {
     /// [`Clone`]: crate::clone::Clone
     /// [`intersperse`]: Iterator::intersperse
     #[inline]
-    #[unstable(feature = "iter_intersperse", reason = "recently added", issue = "79524")]
+    #[stable(feature = "iter_intersperse", since = "1.56.0")]
     fn intersperse_with<G>(self, separator: G) -> IntersperseWith<Self, G>
     where
         Self: Sized,
diff --git a/library/core/tests/cell.rs b/library/core/tests/cell.rs
index 77517879dd2..85a006c5d5b 100644
--- a/library/core/tests/cell.rs
+++ b/library/core/tests/cell.rs
@@ -3,6 +3,38 @@ use core::default::Default;
 use std::mem::drop;
 
 #[test]
+fn smoketest_unsafe_cell() {
+    let mut x = UnsafeCell::new(10);
+    let ref_mut = &mut x;
+    unsafe {
+        // The asserts are repeated in order to ensure that `get()`
+        // is non-mutating.
+        assert_eq!(*ref_mut.get(), 10);
+        assert_eq!(*ref_mut.get(), 10);
+        *ref_mut.get_mut() += 5;
+        assert_eq!(*ref_mut.get(), 15);
+        assert_eq!(*ref_mut.get(), 15);
+        assert_eq!(x.into_inner(), 15);
+    }
+}
+
+#[test]
+fn unsafe_cell_raw_get() {
+    let x = UnsafeCell::new(10);
+    let ptr = &x as *const UnsafeCell<i32>;
+    unsafe {
+        // The asserts are repeated in order to ensure that `raw_get()`
+        // is non-mutating.
+        assert_eq!(*UnsafeCell::raw_get(ptr), 10);
+        assert_eq!(*UnsafeCell::raw_get(ptr), 10);
+        *UnsafeCell::raw_get(ptr) += 5;
+        assert_eq!(*UnsafeCell::raw_get(ptr), 15);
+        assert_eq!(*UnsafeCell::raw_get(ptr), 15);
+        assert_eq!(x.into_inner(), 15);
+    }
+}
+
+#[test]
 fn smoketest_cell() {
     let x = Cell::new(10);
     assert_eq!(x, Cell::new(10));
diff --git a/library/core/tests/lib.rs b/library/core/tests/lib.rs
index 13f483f19b7..7853b571be3 100644
--- a/library/core/tests/lib.rs
+++ b/library/core/tests/lib.rs
@@ -48,7 +48,6 @@
 #![feature(int_log)]
 #![feature(iter_advance_by)]
 #![feature(iter_partition_in_place)]
-#![feature(iter_intersperse)]
 #![feature(iter_is_partitioned)]
 #![feature(iter_order_by)]
 #![feature(iter_map_while)]
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 028a066b5a1..43c7ec5fad3 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -331,7 +331,6 @@
 #![feature(try_reserve)]
 #![feature(try_reserve_kind)]
 #![feature(unboxed_closures)]
-#![feature(unsafe_cell_raw_get)]
 #![feature(unwrap_infallible)]
 #![feature(vec_into_raw_parts)]
 #![feature(vec_spare_capacity)]
diff --git a/library/std/src/sys/unix/fs.rs b/library/std/src/sys/unix/fs.rs
index 6075eb5c7c5..6d7524a733a 100644
--- a/library/std/src/sys/unix/fs.rs
+++ b/library/std/src/sys/unix/fs.rs
@@ -506,7 +506,8 @@ impl Iterator for ReadDir {
             let mut ret = DirEntry { entry: mem::zeroed(), dir: Arc::clone(&self.inner) };
             let mut entry_ptr = ptr::null_mut();
             loop {
-                if readdir64_r(self.inner.dirp.0, &mut ret.entry, &mut entry_ptr) != 0 {
+                let err = readdir64_r(self.inner.dirp.0, &mut ret.entry, &mut entry_ptr);
+                if err != 0 {
                     if entry_ptr.is_null() {
                         // We encountered an error (which will be returned in this iteration), but
                         // we also reached the end of the directory stream. The `end_of_stream`
@@ -514,7 +515,7 @@ impl Iterator for ReadDir {
                         // (instead of looping forever)
                         self.end_of_stream = true;
                     }
-                    return Some(Err(Error::last_os_error()));
+                    return Some(Err(Error::from_raw_os_error(err)));
                 }
                 if entry_ptr.is_null() {
                     return None;
diff --git a/src/doc/unstable-book/src/library-features/asm.md b/src/doc/unstable-book/src/library-features/asm.md
index 4715388408f..a10928a7471 100644
--- a/src/doc/unstable-book/src/library-features/asm.md
+++ b/src/doc/unstable-book/src/library-features/asm.md
@@ -585,6 +585,8 @@ Here is the list of currently supported register classes:
 | PowerPC | `reg` | `r[0-31]` | `r` |
 | PowerPC | `reg_nonzero` | | `r[1-31]` | `b` |
 | PowerPC | `freg` | `f[0-31]` | `f` |
+| PowerPC | `cr` | `cr[0-7]`, `cr` | Only clobbers |
+| PowerPC | `xer` | `xer` | Only clobbers |
 | wasm32 | `local` | None\* | `r` |
 | BPF | `reg` | `r[0-10]` | `r` |
 | BPF | `wreg` | `w[0-10]` | `w` |
@@ -638,6 +640,8 @@ Each register class has constraints on which value types they can be used with.
 | PowerPC | `reg` | None | `i8`, `i16`, `i32` |
 | PowerPC | `reg_nonzero` | None | `i8`, `i16`, `i32` |
 | PowerPC | `freg` | None | `f32`, `f64` |
+| PowerPC | `cr` | N/A | Only clobbers |
+| PowerPC | `xer` | N/A | Only clobbers |
 | wasm32 | `local` | None | `i8` `i16` `i32` `i64` `f32` `f64` |
 | BPF | `reg` | None | `i8` `i16` `i32` `i64` |
 | BPF | `wreg` | `alu32` | `i8` `i16` `i32` |
diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index 7704abc9a72..620b4cdf9da 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -753,7 +753,7 @@ fn assoc_const(
 ) {
     write!(
         w,
-        "{}{}const <a href=\"{}\" class=\"constant\"><b>{}</b></a>: {}",
+        "{}{}const <a href=\"{}\" class=\"constant\">{}</a>: {}",
         extra,
         it.visibility.print_with_space(it.def_id, cx),
         naive_assoc_href(it, link, cx),
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index de32e31ca87..b81acd1a93f 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -13,7 +13,6 @@
 #![feature(never_type)]
 #![feature(once_cell)]
 #![feature(type_ascription)]
-#![feature(iter_intersperse)]
 #![recursion_limit = "256"]
 #![warn(rustc::internal)]
 
diff --git a/src/test/assembly/asm/powerpc-types.rs b/src/test/assembly/asm/powerpc-types.rs
index 1e263649e86..55ca8ee836c 100644
--- a/src/test/assembly/asm/powerpc-types.rs
+++ b/src/test/assembly/asm/powerpc-types.rs
@@ -194,3 +194,15 @@ check_reg!(reg_f32_f0, f32, "0", "f0", "fmr");
 // CHECK: fmr 0, 0
 // CHECK: #NO_APP
 check_reg!(reg_f64_f0, f64, "0", "f0", "fmr");
+
+// CHECK-LABEL: reg_f32_f18:
+// CHECK: #APP
+// CHECK: fmr 18, 18
+// CHECK: #NO_APP
+check_reg!(reg_f32_f18, f32, "18", "f18", "fmr");
+
+// CHECK-LABEL: reg_f64_f18:
+// CHECK: #APP
+// CHECK: fmr 18, 18
+// CHECK: #NO_APP
+check_reg!(reg_f64_f18, f64, "18", "f18", "fmr");
diff --git a/src/test/codegen/asm-powerpc-clobbers.rs b/src/test/codegen/asm-powerpc-clobbers.rs
new file mode 100644
index 00000000000..91a82c60120
--- /dev/null
+++ b/src/test/codegen/asm-powerpc-clobbers.rs
@@ -0,0 +1,48 @@
+// min-llvm-version: 10.0.1
+// revisions: powerpc powerpc64 powerpc64le
+//[powerpc] compile-flags: --target powerpc-unknown-linux-gnu
+//[powerpc] needs-llvm-components: powerpc
+//[powerpc64] compile-flags: --target powerpc64-unknown-linux-gnu
+//[powerpc64] needs-llvm-components: powerpc
+//[powerpc64le] compile-flags: --target powerpc64le-unknown-linux-gnu
+//[powerpc64le] needs-llvm-components: powerpc
+
+#![crate_type = "rlib"]
+#![feature(no_core, rustc_attrs, lang_items)]
+#![no_core]
+
+#[lang = "sized"]
+trait Sized {}
+
+#[rustc_builtin_macro]
+macro_rules! asm {
+    () => {};
+}
+
+// CHECK-LABEL: @cr_clobber
+// CHECK: call void asm sideeffect "", "~{cr}"()
+#[no_mangle]
+pub unsafe fn cr_clobber() {
+    asm!("", out("cr") _, options(nostack, nomem));
+}
+
+// CHECK-LABEL: @cr0_clobber
+// CHECK: call void asm sideeffect "", "~{cr0}"()
+#[no_mangle]
+pub unsafe fn cr0_clobber() {
+    asm!("", out("cr0") _, options(nostack, nomem));
+}
+
+// CHECK-LABEL: @cr5_clobber
+// CHECK: call void asm sideeffect "", "~{cr5}"()
+#[no_mangle]
+pub unsafe fn cr5_clobber() {
+    asm!("", out("cr5") _, options(nostack, nomem));
+}
+
+// CHECK-LABEL: @xer_clobber
+// CHECK: call void asm sideeffect "", "~{xer}"()
+#[no_mangle]
+pub unsafe fn xer_clobber() {
+    asm!("", out("xer") _, options(nostack, nomem));
+}
diff --git a/src/test/rustdoc-gui/font-weight.goml b/src/test/rustdoc-gui/font-weight.goml
index 92ad92a8c34..d8411511c5a 100644
--- a/src/test/rustdoc-gui/font-weight.goml
+++ b/src/test/rustdoc-gui/font-weight.goml
@@ -13,6 +13,21 @@ goto: file://|DOC_PATH|/test_docs/struct.Foo.html
 assert-css: (".impl-items .method", {"font-weight": "600"}, ALL)
 
 goto: file://|DOC_PATH|/lib2/trait.Trait.html
+
+// This is a complex selector, so here's how it works:
+//
+// * //*[@class='docblock type-decl'] — selects element of any tag with classes docblock and type-decl
+// * /pre[@class='rust trait'] — selects immediate child with tag pre and classes rust and trait
+// * /code — selects immediate child with tag code
+// * /a[@class='constant'] — selects immediate child with tag a and class constant
+// * //text() — selects child that is text node
+// * /parent::* — selects immediate parent of the text node (the * means it can be any tag)
+//
+// This uses '/parent::*' as a proxy for the style of the text node.
+// We can't just select the '<a>' because intermediate tags could be added.
+assert-count: ("//*[@class='docblock type-decl']/pre[@class='rust trait']/code/a[@class='constant']//text()/parent::*", 1)
+assert-css: ("//*[@class='docblock type-decl']/pre[@class='rust trait']/code/a[@class='constant']//text()/parent::*", {"font-weight": "400"})
+
 assert-count: (".methods .type", 1)
 assert-css: (".methods .type", {"font-weight": "600"})
 assert-count: (".methods .constant", 1)
diff --git a/src/test/ui/coherence/issue-85026.rs b/src/test/ui/coherence/issue-85026.rs
new file mode 100644
index 00000000000..8b116545aa6
--- /dev/null
+++ b/src/test/ui/coherence/issue-85026.rs
@@ -0,0 +1,10 @@
+#![feature(auto_traits)]
+auto trait AutoTrait {}
+
+// You cannot impl your own `dyn AutoTrait`.
+impl dyn AutoTrait {} //~ERROR E0785
+
+// You cannot impl someone else's `dyn AutoTrait`
+impl dyn Unpin {} //~ERROR E0785
+
+fn main() {}
diff --git a/src/test/ui/coherence/issue-85026.stderr b/src/test/ui/coherence/issue-85026.stderr
new file mode 100644
index 00000000000..a5da19bbfaa
--- /dev/null
+++ b/src/test/ui/coherence/issue-85026.stderr
@@ -0,0 +1,19 @@
+error[E0785]: cannot define inherent `impl` for a dyn auto trait
+  --> $DIR/issue-85026.rs:5:6
+   |
+LL | impl dyn AutoTrait {}
+   |      ^^^^^^^^^^^^^ impl requires at least one non-auto trait
+   |
+   = note: define and implement a new trait or type instead
+
+error[E0785]: cannot define inherent `impl` for a dyn auto trait
+  --> $DIR/issue-85026.rs:8:6
+   |
+LL | impl dyn Unpin {}
+   |      ^^^^^^^^^ impl requires at least one non-auto trait
+   |
+   = note: define and implement a new trait or type instead
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0785`.
diff --git a/src/test/ui/extern/extern-no-mangle.rs b/src/test/ui/extern/extern-no-mangle.rs
new file mode 100644
index 00000000000..ab7c9824af0
--- /dev/null
+++ b/src/test/ui/extern/extern-no-mangle.rs
@@ -0,0 +1,30 @@
+#![warn(unused_attributes)]
+
+// Tests that placing the #[no_mangle] attribute on a foreign fn or static emits
+// a specialized warning.
+// The previous warning only talks about a "function or static" but foreign fns/statics
+// are also not allowed to have #[no_mangle]
+
+// build-pass
+
+extern "C" {
+    #[no_mangle]
+    //~^ WARNING `#[no_mangle]` has no effect on a foreign static
+    //~^^ WARNING this was previously accepted by the compiler
+    pub static FOO: u8;
+
+    #[no_mangle]
+    //~^ WARNING `#[no_mangle]` has no effect on a foreign function
+    //~^^ WARNING this was previously accepted by the compiler
+    pub fn bar();
+}
+
+fn no_new_warn() {
+    // Should emit the generic "not a function or static" warning
+    #[no_mangle]
+    //~^ WARNING attribute should be applied to a free function, impl method or static
+    //~^^ WARNING this was previously accepted by the compiler
+    let x = 0_u8;
+}
+
+fn main() {}
diff --git a/src/test/ui/extern/extern-no-mangle.stderr b/src/test/ui/extern/extern-no-mangle.stderr
new file mode 100644
index 00000000000..b5642814114
--- /dev/null
+++ b/src/test/ui/extern/extern-no-mangle.stderr
@@ -0,0 +1,42 @@
+warning: attribute should be applied to a free function, impl method or static
+  --> $DIR/extern-no-mangle.rs:24:5
+   |
+LL |     #[no_mangle]
+   |     ^^^^^^^^^^^^
+...
+LL |     let x = 0_u8;
+   |     ------------- not a free function, impl method or static
+   |
+note: the lint level is defined here
+  --> $DIR/extern-no-mangle.rs:1:9
+   |
+LL | #![warn(unused_attributes)]
+   |         ^^^^^^^^^^^^^^^^^
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: `#[no_mangle]` has no effect on a foreign static
+  --> $DIR/extern-no-mangle.rs:11:5
+   |
+LL |     #[no_mangle]
+   |     ^^^^^^^^^^^^ help: remove this attribute
+...
+LL |     pub static FOO: u8;
+   |     ------------------- foreign static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: symbol names in extern blocks are not mangled
+
+warning: `#[no_mangle]` has no effect on a foreign function
+  --> $DIR/extern-no-mangle.rs:16:5
+   |
+LL |     #[no_mangle]
+   |     ^^^^^^^^^^^^ help: remove this attribute
+...
+LL |     pub fn bar();
+   |     ------------- foreign function
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: symbol names in extern blocks are not mangled
+
+warning: 3 warnings emitted
+