Auto merge of #78127 - JohnTitor:rollup-p1bxtqq, r=JohnTitor

Rollup of 10 pull requests

Successful merges:

 - #77612 (BTreeMap: test invariants more thoroughly and more readably)
 - #77761 (Assert that pthread mutex initialization succeeded)
 - #77778 ([x.py setup] Allow setting up git hooks from other worktrees)
 - #77838 (const keyword: brief paragraph on 'const fn')
 - #77923 ([net] apply clippy lints)
 - #77931 (Fix false positive for `unused_parens` lint)
 - #77959 (Tweak ui-tests structure)
 - #78105 (change name in .mailmap)
 - #78111 (Trait predicate ambiguities are not always in `Self`)
 - #78121 (Do not ICE on pattern that uses a binding multiple times in generator)

Failed merges:

r? `@ghost`

.mailmap

@@ -29,7 +29,6 @@ Ariel Ben-Yehuda <arielb1@mail.tau.ac.il> arielb1 <arielb1@mail.tau.ac.il>
 Austin Seipp <mad.one@gmail.com> <as@hacks.yi.org>
 Aydin Kim <ladinjin@hanmail.net> aydin.kim <aydin.kim@samsung.com>
 Barosl Lee <vcs@barosl.com> Barosl LEE <github@barosl.com>
-Bastian Kauschke <bastian_kauschke@hotmail.de>
 Ben Alpert <ben@benalpert.com> <spicyjalapeno@gmail.com>
 Ben Sago <ogham@users.noreply.github.com> Ben S <ogham@bsago.me>
 Ben Sago <ogham@users.noreply.github.com> Ben S <ogham@users.noreply.github.com>
@@ -161,6 +160,7 @@ Kyle J Strand <batmanaod@gmail.com> <kyle.j.strand@gmail.com>
 Kyle J Strand <batmanaod@gmail.com> <kyle.strand@pieinsurance.com>
 Kyle J Strand <batmanaod@gmail.com> <kyle.strand@rms.com>
 Laurențiu Nicola <lnicola@dend.ro>
+lcnr <bastian_kauschke@hotmail.de>
 Lee Jeffery <leejeffery@gmail.com> Lee Jeffery <lee@leejeffery.co.uk>
 Lee Wondong <wdlee91@gmail.com>
 Lennart Kudling <github@kudling.de>

compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs

@@ -91,17 +91,6 @@ impl<'a, 'tcx> Visitor<'tcx> for FindHirNodeVisitor<'a, 'tcx> {
         if let (None, Some(ty)) =
             (self.found_local_pattern, self.node_ty_contains_target(local.hir_id))
         {
-            // FIXME: There's a trade-off here - we can either check that our target span
-            // is contained in `local.span` or not. If we choose to check containment
-            // we can avoid some spurious suggestions (see #72690), but we lose
-            // the ability to report on things like:
-            //
-            // ```
-            // let x = vec![];
-            // ```
-            //
-            // because the target span will be in the macro expansion of `vec![]`.
-            // At present we choose not to check containment.
             self.found_local_pattern = Some(&*local.pat);
             self.found_node_ty = Some(ty);
         }
@@ -113,10 +102,8 @@ impl<'a, 'tcx> Visitor<'tcx> for FindHirNodeVisitor<'a, 'tcx> {
             if let (None, Some(ty)) =
                 (self.found_arg_pattern, self.node_ty_contains_target(param.hir_id))
             {
-                if self.target_span.contains(param.pat.span) {
+                self.found_arg_pattern = Some(&*param.pat);
-                    self.found_arg_pattern = Some(&*param.pat);
+                self.found_node_ty = Some(ty);
-                    self.found_node_ty = Some(ty);
-                }
             }
         }
         intravisit::walk_body(self, body);

compiler/rustc_lint/src/unused.rs

@@ -751,13 +751,20 @@ impl UnusedDelimLint for UnusedParens {
                 if !Self::is_expr_delims_necessary(inner, followed_by_block)
                     && value.attrs.is_empty()
                     && !value.span.from_expansion()
+                    && (ctx != UnusedDelimsCtx::LetScrutineeExpr
+                        || match inner.kind {
+                            ast::ExprKind::Binary(
+                                rustc_span::source_map::Spanned { node, .. },
+                                _,
+                                _,
+                            ) if node.lazy() => false,
+                            _ => true,
+                        })
                 {
                     self.emit_unused_delims_expr(cx, value, ctx, left_pos, right_pos)
                 }
             }
             ast::ExprKind::Let(_, ref expr) => {
-                // FIXME(#60336): Properly handle `let true = (false && true)`
-                // actually needing the parenthesis.
                 self.check_unused_delims_expr(
                     cx,
                     expr,

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -1462,9 +1462,8 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
         let bound_predicate = predicate.bound_atom();
         let mut err = match bound_predicate.skip_binder() {
             ty::PredicateAtom::Trait(data, _) => {
-                let self_ty = data.trait_ref.self_ty();
                 let trait_ref = bound_predicate.rebind(data.trait_ref);
-                debug!("self_ty {:?} {:?} trait_ref {:?}", self_ty, self_ty.kind(), trait_ref);
+                debug!("trait_ref {:?}", trait_ref);
 
                 if predicate.references_error() {
                     return;
@@ -1479,6 +1478,17 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
                 // known, since we don't dispatch based on region
                 // relationships.
 
+                // Pick the first substitution that still contains inference variables as the one
+                // we're going to emit an error for. If there are none (see above), fall back to
+                // the substitution for `Self`.
+                let subst = {
+                    let substs = data.trait_ref.substs;
+                    substs
+                        .iter()
+                        .find(|s| s.has_infer_types_or_consts())
+                        .unwrap_or_else(|| substs[0])
+                };
+
                 // This is kind of a hack: it frequently happens that some earlier
                 // error prevents types from being fully inferred, and then we get
                 // a bunch of uninteresting errors saying something like "<generic
@@ -1495,21 +1505,11 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
                 // check upstream for type errors and don't add the obligations to
                 // begin with in those cases.
                 if self.tcx.lang_items().sized_trait() == Some(trait_ref.def_id()) {
-                    self.emit_inference_failure_err(
+                    self.emit_inference_failure_err(body_id, span, subst, ErrorCode::E0282).emit();
-                        body_id,
-                        span,
-                        self_ty.into(),
-                        ErrorCode::E0282,
-                    )
-                    .emit();
                     return;
                 }
-                let mut err = self.emit_inference_failure_err(
+                let mut err =
-                    body_id,
+                    self.emit_inference_failure_err(body_id, span, subst, ErrorCode::E0283);
-                    span,
-                    self_ty.into(),
-                    ErrorCode::E0283,
-                );
                 err.note(&format!("cannot satisfy `{}`", predicate));
                 if let ObligationCauseCode::ItemObligation(def_id) = obligation.cause.code {
                     self.suggest_fully_qualified_path(&mut err, def_id, span, trait_ref.def_id());

compiler/rustc_typeck/src/check/generator_interior.rs

@@ -250,10 +250,7 @@ impl<'a, 'tcx> Visitor<'tcx> for InteriorVisitor<'a, 'tcx> {
             let mut scope_var_ids =
                 self.guard_bindings.pop().expect("should have pushed at least one earlier");
             for var_id in scope_var_ids.drain(..) {
-                assert!(
+                self.guard_bindings_set.remove(&var_id);
-                    self.guard_bindings_set.remove(&var_id),
-                    "variable should be placed in scope earlier"
-                );
             }
         }
         self.visit_expr(body);

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

@@ -1,4 +1,4 @@
-use super::super::{navigate::Position, node, DeterministicRng};
+use super::super::{node, DeterministicRng};
 use super::Entry::{Occupied, Vacant};
 use super::*;
 use crate::boxed::Box;
@@ -7,7 +7,7 @@ use crate::rc::Rc;
 use crate::string::{String, ToString};
 use crate::vec::Vec;
 use std::convert::TryFrom;
-use std::iter::FromIterator;
+use std::iter::{self, FromIterator};
 use std::mem;
 use std::ops::Bound::{self, Excluded, Included, Unbounded};
 use std::ops::RangeBounds;
@@ -42,19 +42,6 @@ fn test_all_refs<'a, T: 'a>(dummy: &mut T, iter: impl Iterator<Item = &'a mut T>
     }
 }
 
-struct SeriesChecker<T> {
-    previous: Option<T>,
-}
-
-impl<T: Copy + Debug + Ord> SeriesChecker<T> {
-    fn is_ascending(&mut self, next: T) {
-        if let Some(previous) = self.previous {
-            assert!(previous < next, "{:?} >= {:?}", previous, next);
-        }
-        self.previous = Some(next);
-    }
-}
-
 impl<'a, K: 'a, V: 'a> BTreeMap<K, V> {
     /// Panics if the map (or the code navigating it) is corrupted.
     fn check(&self)
@@ -63,44 +50,10 @@ impl<'a, K: 'a, V: 'a> BTreeMap<K, V> {
     {
         if let Some(root) = &self.root {
             let root_node = root.node_as_ref();
-            let mut checker = SeriesChecker { previous: None };
+            assert!(root_node.ascend().is_err());
-            let mut internal_length = 0;
+            root_node.assert_back_pointers();
-            let mut internal_kv_count = 0;
+            root_node.assert_ascending();
-            let mut leaf_length = 0;
+            assert_eq!(self.length, root_node.assert_and_add_lengths());
-            root_node.visit_nodes_in_order(|pos| match pos {
-                Position::Leaf(node) => {
-                    let is_root = root_node.height() == 0;
-                    let min_len = if is_root { 0 } else { node::MIN_LEN };
-                    assert!(node.len() >= min_len, "{} < {}", node.len(), min_len);
-
-                    for idx in 0..node.len() {
-                        let key = *unsafe { node.key_at(idx) };
-                        checker.is_ascending(key);
-                    }
-                    leaf_length += node.len();
-                }
-                Position::Internal(node) => {
-                    let is_root = root_node.height() == node.height();
-                    let min_len = if is_root { 1 } else { node::MIN_LEN };
-                    assert!(node.len() >= min_len, "{} < {}", node.len(), min_len);
-
-                    for idx in 0..=node.len() {
-                        let edge = unsafe { node::Handle::new_edge(node, idx) };
-                        assert!(edge.descend().ascend().ok().unwrap() == edge);
-                    }
-
-                    internal_length += node.len();
-                }
-                Position::InternalKV(kv) => {
-                    let key = *kv.into_kv().0;
-                    checker.is_ascending(key);
-
-                    internal_kv_count += 1;
-                }
-            });
-            assert_eq!(internal_length, internal_kv_count);
-            assert_eq!(root_node.calc_length(), internal_length + leaf_length);
-            assert_eq!(self.length, internal_length + leaf_length);
         } else {
             assert_eq!(self.length, 0);
         }
@@ -116,28 +69,7 @@ impl<'a, K: 'a, V: 'a> BTreeMap<K, V> {
         K: Debug,
     {
         if let Some(root) = self.root.as_ref() {
-            let mut result = String::new();
+            root.node_as_ref().dump_keys()
-            let root_node = root.node_as_ref();
-            root_node.visit_nodes_in_order(|pos| match pos {
-                Position::Leaf(leaf) => {
-                    let depth = root_node.height();
-                    let indent = "  ".repeat(depth);
-                    result += &format!("\n{}", indent);
-                    for idx in 0..leaf.len() {
-                        if idx > 0 {
-                            result += ", ";
-                        }
-                        result += &format!("{:?}", unsafe { leaf.key_at(idx) });
-                    }
-                }
-                Position::Internal(_) => {}
-                Position::InternalKV(kv) => {
-                    let depth = root_node.height() - kv.into_node().height();
-                    let indent = "  ".repeat(depth);
-                    result += &format!("\n{}{:?}", indent, kv.into_kv().0);
-                }
-            });
-            result
         } else {
             String::from("not yet allocated")
         }
@@ -170,7 +102,6 @@ fn test_levels() {
         let last_key = *map.last_key_value().unwrap().0;
         map.insert(last_key + 1, ());
     }
-    println!("{}", map.dump_keys());
     map.check();
     // Structure:
     // - 1 element in internal root node with 2 children
@@ -372,7 +303,7 @@ fn test_iter_rev() {
 fn do_test_iter_mut_mutation<T>(size: usize)
 where
     T: Copy + Debug + Ord + TryFrom<usize>,
-    <T as std::convert::TryFrom<usize>>::Error: std::fmt::Debug,
+    <T as TryFrom<usize>>::Error: Debug,
 {
     let zero = T::try_from(0).unwrap();
     let mut map: BTreeMap<T, T> = (0..size).map(|i| (T::try_from(i).unwrap(), zero)).collect();
@@ -857,7 +788,7 @@ mod test_drain_filter {
     fn consuming_nothing() {
         let pairs = (0..3).map(|i| (i, i));
         let mut map: BTreeMap<_, _> = pairs.collect();
-        assert!(map.drain_filter(|_, _| false).eq(std::iter::empty()));
+        assert!(map.drain_filter(|_, _| false).eq(iter::empty()));
         map.check();
     }
 
@@ -878,7 +809,7 @@ mod test_drain_filter {
                 *v += 6;
                 false
             })
-            .eq(std::iter::empty())
+            .eq(iter::empty())
         );
         assert!(map.keys().copied().eq(0..3));
         assert!(map.values().copied().eq(6..9));

library/alloc/src/collections/btree/node/tests.rs

@@ -1,6 +1,111 @@
+use super::super::navigate;
 use super::*;
+use crate::fmt::Debug;
+use crate::string::String;
 use core::cmp::Ordering::*;
 
+impl<'a, K: 'a, V: 'a> NodeRef<marker::Immut<'a>, K, V, marker::LeafOrInternal> {
+    pub fn assert_back_pointers(self) {
+        match self.force() {
+            ForceResult::Leaf(_) => {}
+            ForceResult::Internal(node) => {
+                for idx in 0..=node.len() {
+                    let edge = unsafe { Handle::new_edge(node, idx) };
+                    let child = edge.descend();
+                    assert!(child.ascend().ok() == Some(edge));
+                    child.assert_back_pointers();
+                }
+            }
+        }
+    }
+
+    pub fn assert_ascending(self)
+    where
+        K: Copy + Debug + Ord,
+    {
+        struct SeriesChecker<T> {
+            previous: Option<T>,
+        }
+        impl<T: Copy + Debug + Ord> SeriesChecker<T> {
+            fn is_ascending(&mut self, next: T) {
+                if let Some(previous) = self.previous {
+                    assert!(previous < next, "{:?} >= {:?}", previous, next);
+                }
+                self.previous = Some(next);
+            }
+        }
+
+        let mut checker = SeriesChecker { previous: None };
+        self.visit_nodes_in_order(|pos| match pos {
+            navigate::Position::Leaf(node) => {
+                for idx in 0..node.len() {
+                    let key = *unsafe { node.key_at(idx) };
+                    checker.is_ascending(key);
+                }
+            }
+            navigate::Position::InternalKV(kv) => {
+                let key = *kv.into_kv().0;
+                checker.is_ascending(key);
+            }
+            navigate::Position::Internal(_) => {}
+        });
+    }
+
+    pub fn assert_and_add_lengths(self) -> usize {
+        let mut internal_length = 0;
+        let mut internal_kv_count = 0;
+        let mut leaf_length = 0;
+        self.visit_nodes_in_order(|pos| match pos {
+            navigate::Position::Leaf(node) => {
+                let is_root = self.height() == 0;
+                let min_len = if is_root { 0 } else { MIN_LEN };
+                assert!(node.len() >= min_len, "{} < {}", node.len(), min_len);
+                leaf_length += node.len();
+            }
+            navigate::Position::Internal(node) => {
+                let is_root = self.height() == node.height();
+                let min_len = if is_root { 1 } else { MIN_LEN };
+                assert!(node.len() >= min_len, "{} < {}", node.len(), min_len);
+                internal_length += node.len();
+            }
+            navigate::Position::InternalKV(_) => {
+                internal_kv_count += 1;
+            }
+        });
+        assert_eq!(internal_length, internal_kv_count);
+        let total = internal_length + leaf_length;
+        assert_eq!(self.calc_length(), total);
+        total
+    }
+
+    pub fn dump_keys(self) -> String
+    where
+        K: Debug,
+    {
+        let mut result = String::new();
+        self.visit_nodes_in_order(|pos| match pos {
+            navigate::Position::Leaf(leaf) => {
+                let depth = self.height();
+                let indent = "  ".repeat(depth);
+                result += &format!("\n{}", indent);
+                for idx in 0..leaf.len() {
+                    if idx > 0 {
+                        result += ", ";
+                    }
+                    result += &format!("{:?}", unsafe { leaf.key_at(idx) });
+                }
+            }
+            navigate::Position::Internal(_) => {}
+            navigate::Position::InternalKV(kv) => {
+                let depth = self.height() - kv.into_node().height();
+                let indent = "  ".repeat(depth);
+                result += &format!("\n{}{:?}", indent, kv.into_kv().0);
+            }
+        });
+        result
+    }
+}
+
 #[test]
 fn test_splitpoint() {
     for idx in 0..=CAPACITY {

library/std/src/keyword_docs.rs

@@ -102,7 +102,9 @@ mod break_keyword {}
 
 #[doc(keyword = "const")]
 //
-/// Compile-time constants and deterministic functions.
+/// Compile-time constants and compile-time evaluable functions.
+///
+/// ## Compile-time constants
 ///
 /// Sometimes a certain value is used many times throughout a program, and it can become
 /// inconvenient to copy it over and over. What's more, it's not always possible or desirable to
@@ -145,15 +147,28 @@ mod break_keyword {}
 ///
 /// Constants, like statics, should always be in `SCREAMING_SNAKE_CASE`.
 ///
+/// For more detail on `const`, see the [Rust Book] or the [Reference].
+///
+/// ## Compile-time evaluable functions
+///
+/// The other main use of the `const` keyword is in `const fn`. This marks a function as being
+/// callable in the body of a `const` or `static` item and in array initializers (commonly called
+/// "const contexts"). `const fn` are restricted in the set of operations they can perform, to
+/// ensure that they can be evaluated at compile-time. See the [Reference][const-eval] for more
+/// detail.
+///
+/// Turning a `fn` into a `const fn` has no effect on run-time uses of that function.
+///
+/// ## Other uses of `const`
+///
 /// The `const` keyword is also used in raw pointers in combination with `mut`, as seen in `*const
 /// T` and `*mut T`. More about `const` as used in raw pointers can be read at the Rust docs for the [pointer primitive].
 ///
-/// For more detail on `const`, see the [Rust Book] or the [Reference].
-///
 /// [pointer primitive]: primitive.pointer.html
 /// [Rust Book]:
 /// ../book/ch03-01-variables-and-mutability.html#differences-between-variables-and-constants
 /// [Reference]: ../reference/items/constant-items.html
+/// [const-eval]: ../reference/const_eval.html
 mod const_keyword {}
 
 #[doc(keyword = "continue")]

library/std/src/net/ip.rs

@@ -456,10 +456,7 @@ impl Ipv4Addr {
     #[rustc_const_unstable(feature = "const_ipv4", issue = "76205")]
     #[stable(since = "1.7.0", feature = "ip_17")]
     pub const fn is_link_local(&self) -> bool {
-        match self.octets() {
+        matches!(self.octets(), [169, 254, ..])
-            [169, 254, ..] => true,
-            _ => false,
-        }
     }
 
     /// Returns [`true`] if the address appears to be globally routable.
@@ -1262,10 +1259,7 @@ impl Ipv6Addr {
     /// [RFC 4291 errata 4406]: https://www.rfc-editor.org/errata/eid4406
     #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
     pub const fn is_unicast_link_local_strict(&self) -> bool {
-        (self.segments()[0] & 0xffff) == 0xfe80
+        matches!(self.segments(), [0xfe80, 0, 0, 0, ..])
-            && (self.segments()[1] & 0xffff) == 0
-            && (self.segments()[2] & 0xffff) == 0
-            && (self.segments()[3] & 0xffff) == 0
     }
 
     /// Returns [`true`] if the address is a unicast link-local address (`fe80::/10`).

library/std/src/sys/unix/mod.rs

@@ -220,6 +220,10 @@ where
     }
 }
 
+pub fn cvt_nz(error: libc::c_int) -> crate::io::Result<()> {
+    if error == 0 { Ok(()) } else { Err(crate::io::Error::from_raw_os_error(error)) }
+}
+
 // On Unix-like platforms, libc::abort will unregister signal handlers
 // including the SIGABRT handler, preventing the abort from being blocked, and
 // fclose streams, with the side effect of flushing them so libc buffered

library/std/src/sys/unix/mutex.rs

@@ -1,5 +1,6 @@
 use crate::cell::UnsafeCell;
 use crate::mem::MaybeUninit;
+use crate::sys::cvt_nz;
 
 pub struct Mutex {
     inner: UnsafeCell<libc::pthread_mutex_t>,
@@ -51,14 +52,11 @@ impl Mutex {
         // PTHREAD_MUTEX_NORMAL which is guaranteed to deadlock if we try to
         // re-lock it from the same thread, thus avoiding undefined behavior.
         let mut attr = MaybeUninit::<libc::pthread_mutexattr_t>::uninit();
-        let r = libc::pthread_mutexattr_init(attr.as_mut_ptr());
+        cvt_nz(libc::pthread_mutexattr_init(attr.as_mut_ptr())).unwrap();
-        debug_assert_eq!(r, 0);
+        let attr = PthreadMutexAttr(&mut attr);
-        let r = libc::pthread_mutexattr_settype(attr.as_mut_ptr(), libc::PTHREAD_MUTEX_NORMAL);
+        cvt_nz(libc::pthread_mutexattr_settype(attr.0.as_mut_ptr(), libc::PTHREAD_MUTEX_NORMAL))
-        debug_assert_eq!(r, 0);
+            .unwrap();
-        let r = libc::pthread_mutex_init(self.inner.get(), attr.as_ptr());
+        cvt_nz(libc::pthread_mutex_init(self.inner.get(), attr.0.as_ptr())).unwrap();
-        debug_assert_eq!(r, 0);
-        let r = libc::pthread_mutexattr_destroy(attr.as_mut_ptr());
-        debug_assert_eq!(r, 0);
     }
     #[inline]
     pub unsafe fn lock(&self) {
@@ -106,15 +104,11 @@ impl ReentrantMutex {
 
     pub unsafe fn init(&self) {
         let mut attr = MaybeUninit::<libc::pthread_mutexattr_t>::uninit();
-        let result = libc::pthread_mutexattr_init(attr.as_mut_ptr());
+        cvt_nz(libc::pthread_mutexattr_init(attr.as_mut_ptr())).unwrap();
-        debug_assert_eq!(result, 0);
+        let attr = PthreadMutexAttr(&mut attr);
-        let result =
+        cvt_nz(libc::pthread_mutexattr_settype(attr.0.as_mut_ptr(), libc::PTHREAD_MUTEX_RECURSIVE))
-            libc::pthread_mutexattr_settype(attr.as_mut_ptr(), libc::PTHREAD_MUTEX_RECURSIVE);
+            .unwrap();
-        debug_assert_eq!(result, 0);
+        cvt_nz(libc::pthread_mutex_init(self.inner.get(), attr.0.as_ptr())).unwrap();
-        let result = libc::pthread_mutex_init(self.inner.get(), attr.as_ptr());
-        debug_assert_eq!(result, 0);
-        let result = libc::pthread_mutexattr_destroy(attr.as_mut_ptr());
-        debug_assert_eq!(result, 0);
     }
 
     pub unsafe fn lock(&self) {
@@ -137,3 +131,14 @@ impl ReentrantMutex {
         debug_assert_eq!(result, 0);
     }
 }
+
+struct PthreadMutexAttr<'a>(&'a mut MaybeUninit<libc::pthread_mutexattr_t>);
+
+impl Drop for PthreadMutexAttr<'_> {
+    fn drop(&mut self) {
+        unsafe {
+            let result = libc::pthread_mutexattr_destroy(self.0.as_mut_ptr());
+            debug_assert_eq!(result, 0);
+        }
+    }
+}

library/std/src/sys/unix/process/process_unix.rs

@@ -281,7 +281,7 @@ impl Command {
         envp: Option<&CStringArray>,
     ) -> io::Result<Option<Process>> {
         use crate::mem::MaybeUninit;
-        use crate::sys;
+        use crate::sys::{self, cvt_nz};
 
         if self.get_gid().is_some()
             || self.get_uid().is_some()
@@ -343,10 +343,6 @@ impl Command {
             }
         }
 
-        fn cvt_nz(error: libc::c_int) -> io::Result<()> {
-            if error == 0 { Ok(()) } else { Err(io::Error::from_raw_os_error(error)) }
-        }
-
         unsafe {
             let mut attrs = MaybeUninit::uninit();
             cvt_nz(libc::posix_spawnattr_init(attrs.as_mut_ptr()))?;

src/bootstrap/setup.rs

@@ -1,6 +1,7 @@
 use crate::{t, VERSION};
 use std::fmt::Write as _;
 use std::path::{Path, PathBuf};
+use std::process::Command;
 use std::str::FromStr;
 use std::{
     env, fmt, fs,
@@ -196,10 +197,17 @@ simply delete the `pre-commit` file from .git/hooks."
 
     Ok(if should_install {
         let src = src_path.join("src").join("etc").join("pre-commit.sh");
-        let dst = src_path.join(".git").join("hooks").join("pre-commit");
+        let git = t!(Command::new("git").args(&["rev-parse", "--git-common-dir"]).output().map(
-        match fs::hard_link(src, dst) {
+            |output| {
+                assert!(output.status.success(), "failed to run `git`");
+                PathBuf::from(t!(String::from_utf8(output.stdout)).trim())
+            }
+        ));
+        let dst = git.join("hooks").join("pre-commit");
+        match fs::hard_link(src, &dst) {
             Err(e) => println!(
-                "x.py encountered an error -- do you already have the git hook installed?\n{}",
+                "error: could not create hook {}: do you already have the git hook installed?\n{}",
+                dst.display(),
                 e
             ),
             Ok(_) => println!("Linked `src/etc/pre-commit.sh` to `.git/hooks/pre-commit`"),

src/test/ui/closure-expected-type/expect-two-infer-vars-supply-ty-with-bound-region.stderr

@@ -1,8 +1,8 @@
 error[E0282]: type annotations needed
-  --> $DIR/expect-two-infer-vars-supply-ty-with-bound-region.rs:8:5
+  --> $DIR/expect-two-infer-vars-supply-ty-with-bound-region.rs:8:27
    |
 LL |     with_closure(|x: u32, y| {});
-   |     ^^^^^^^^^^^^ cannot infer type for type parameter `B` declared on the function `with_closure`
+   |                           ^ consider giving this closure parameter a type
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-23046.rs

@@ -14,7 +14,7 @@ pub fn let_<'var, VAR, F: for<'v> Fn(Expr<'v, VAR>) -> Expr<'v, VAR>>
 }
 
 fn main() {
-    let ex = |x| {
+    let ex = |x| { //~ ERROR type annotations needed
-        let_(add(x,x), |y| { //~ ERROR type annotations needed
+        let_(add(x,x), |y| {
             let_(add(x, x), |x|x)})};
 }

src/test/ui/issues/issue-23046.stderr

@@ -1,13 +1,8 @@
-error[E0282]: type annotations needed for the closure `fn(Expr<'_, _>) -> Expr<'_, _>`
+error[E0282]: type annotations needed for `Expr<'_, VAR>`
-  --> $DIR/issue-23046.rs:18:9
+  --> $DIR/issue-23046.rs:17:15
    |
-LL |         let_(add(x,x), |y| {
+LL |     let ex = |x| {
-   |         ^^^^ cannot infer type for type parameter `VAR` declared on the function `let_`
+   |               ^ consider giving this closure parameter the explicit type `Expr<'_, VAR>`, where the type parameter `VAR` is specified
-   |
-help: give this closure an explicit return type without `_` placeholders
-   |
-LL |             let_(add(x, x), |x|-> Expr<'_, _> { x })})};
-   |                                ^^^^^^^^^^^^^^^^   ^
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-72690.stderr

@@ -2,7 +2,7 @@ error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:7:5
    |
 LL |     String::from("x".as_ref());
-   |     ^^^^^^^^^^^^ cannot infer type for struct `String`
+   |     ^^^^^^^^^^^^ cannot infer type for reference `&_`
    |
    = note: cannot satisfy `String: From<&_>`
    = note: required by `from`
@@ -13,11 +13,13 @@ error[E0282]: type annotations needed
 LL |     |x| String::from("x".as_ref());
    |      ^ consider giving this closure parameter a type
 
-error[E0283]: type annotations needed
+error[E0283]: type annotations needed for `&T`
   --> $DIR/issue-72690.rs:15:17
    |
 LL |     let _ = "x".as_ref();
-   |                 ^^^^^^ cannot infer type for type `str`
+   |         -       ^^^^^^ cannot infer type for type parameter `T` declared on the trait `AsRef`
+   |         |
+   |         consider giving this pattern the explicit type `&T`, where the type parameter `T` is specified
    |
    = note: cannot satisfy `str: AsRef<_>`
 
@@ -25,7 +27,7 @@ error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:19:5
    |
 LL |     String::from("x".as_ref());
-   |     ^^^^^^^^^^^^ cannot infer type for struct `String`
+   |     ^^^^^^^^^^^^ cannot infer type for reference `&_`
    |
    = note: cannot satisfy `String: From<&_>`
    = note: required by `from`
@@ -34,7 +36,7 @@ error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:25:5
    |
 LL |     String::from("x".as_ref());
-   |     ^^^^^^^^^^^^ cannot infer type for struct `String`
+   |     ^^^^^^^^^^^^ cannot infer type for reference `&_`
    |
    = note: cannot satisfy `String: From<&_>`
    = note: required by `from`
@@ -43,41 +45,34 @@ error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:33:5
    |
 LL |     String::from("x".as_ref());
-   |     ^^^^^^^^^^^^ cannot infer type for struct `String`
+   |     ^^^^^^^^^^^^ cannot infer type for reference `&_`
    |
    = note: cannot satisfy `String: From<&_>`
    = note: required by `from`
 
-error[E0283]: type annotations needed for `String`
+error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:41:5
    |
 LL |     String::from("x".as_ref());
-   |     ^^^^^^^^^^^^ cannot infer type for struct `String`
+   |     ^^^^^^^^^^^^ cannot infer type for reference `&_`
-LL |     let _ = String::from("x");
-   |         - consider giving this pattern a type
    |
    = note: cannot satisfy `String: From<&_>`
    = note: required by `from`
 
-error[E0283]: type annotations needed for `String`
+error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:47:5
    |
-LL |     let _ = String::from("x");
-   |         - consider giving this pattern a type
 LL |     String::from("x".as_ref());
-   |     ^^^^^^^^^^^^ cannot infer type for struct `String`
+   |     ^^^^^^^^^^^^ cannot infer type for reference `&_`
    |
    = note: cannot satisfy `String: From<&_>`
    = note: required by `from`
 
-error[E0283]: type annotations needed for `String`
+error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:55:5
    |
-LL |     let _ = String::from("x");
-   |         - consider giving this pattern a type
-...
 LL |     String::from("x".as_ref());
-   |     ^^^^^^^^^^^^ cannot infer type for struct `String`
+   |     ^^^^^^^^^^^^ cannot infer type for reference `&_`
    |
    = note: cannot satisfy `String: From<&_>`
    = note: required by `from`

src/test/ui/issues/issue-78115.rs

@@ -0,0 +1,19 @@
+// Regression test for issue #78115: "ICE: variable should be placed in scope earlier"
+
+// check-pass
+// edition:2018
+
+#[allow(dead_code)]
+struct Foo {
+    a: ()
+}
+
+async fn _bar() {
+    let foo = Foo { a: () };
+    match foo {
+        Foo { a: _a } | Foo { a: _a } if true => {}
+        _ => {}
+    }
+}
+
+fn main() {}

src/test/ui/lint/lint-unnecessary-parens.fixed

@@ -60,6 +60,8 @@ fn main() {
     if (v == X { y: true }) {}
     if (X { y: true } == v) {}
     if (X { y: false }.y) {}
+    // this shouldn't warn, because the parens are necessary to disambiguate let chains
+    if let true = (true && false) {}
 
     while (X { y: false }.foo(true)) {}
     while (true | X { y: false }.y) {}

src/test/ui/lint/lint-unnecessary-parens.rs

@@ -60,6 +60,8 @@ fn main() {
     if (v == X { y: true }) {}
     if (X { y: true } == v) {}
     if (X { y: false }.y) {}
+    // this shouldn't warn, because the parens are necessary to disambiguate let chains
+    if let true = (true && false) {}
 
     while (X { y: false }.foo(true)) {}
     while (true | X { y: false }.y) {}

src/test/ui/lint/lint-unnecessary-parens.stderr

@@ -83,25 +83,25 @@ LL |     while let 1 = (2) {}
    |                   ^^^ help: remove these parentheses
 
 error: unnecessary parentheses around method argument
-  --> $DIR/lint-unnecessary-parens.rs:71:24
+  --> $DIR/lint-unnecessary-parens.rs:73:24
    |
 LL |     X { y: false }.foo((true));
    |                        ^^^^^^ help: remove these parentheses
 
 error: unnecessary parentheses around assigned value
-  --> $DIR/lint-unnecessary-parens.rs:73:18
+  --> $DIR/lint-unnecessary-parens.rs:75:18
    |
 LL |     let mut _a = (0);
    |                  ^^^ help: remove these parentheses
 
 error: unnecessary parentheses around assigned value
-  --> $DIR/lint-unnecessary-parens.rs:74:10
+  --> $DIR/lint-unnecessary-parens.rs:76:10
    |
 LL |     _a = (0);
    |          ^^^ help: remove these parentheses
 
 error: unnecessary parentheses around assigned value
-  --> $DIR/lint-unnecessary-parens.rs:75:11
+  --> $DIR/lint-unnecessary-parens.rs:77:11
    |
 LL |     _a += (1);
    |           ^^^ help: remove these parentheses