Rollup of 12 pull requests

compiler/rustc_ast/src/attr/mod.rs

@@ -360,7 +360,7 @@ pub fn list_contains_name(items: &[NestedMetaItem], name: Symbol) -> bool {
 impl MetaItem {
  fn token_trees_and_spacings(&self) -> Vec<TreeAndSpacing> {
  let mut idents = vec![];
- let mut last_pos = BytePos(0 as u32);
+ let mut last_pos = BytePos(0_u32);
  for (i, segment) in self.path.segments.iter().enumerate() {
  let is_first = i == 0;
  if !is_first {

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

@@ -739,7 +739,6 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
  "cannot infer {} {} {} `{}`{}",
  kind_str, preposition, descr, type_name, parent_desc
  )
- .into()
  }
  }
 }

compiler/rustc_interface/src/util.rs

@@ -246,10 +246,10 @@ pub fn get_codegen_backend(sopts: &config::Options) -> Box<dyn CodegenBackend> {
 
  INIT.call_once(|| {
  #[cfg(feature = "llvm")]
- const DEFAULT_CODEGEN_BACKEND: &'static str = "llvm";
+ const DEFAULT_CODEGEN_BACKEND: &str = "llvm";
 
  #[cfg(not(feature = "llvm"))]
- const DEFAULT_CODEGEN_BACKEND: &'static str = "cranelift";
+ const DEFAULT_CODEGEN_BACKEND: &str = "cranelift";
 
  let codegen_name = sopts
  .debugging_opts
@@ -414,11 +414,10 @@ pub fn get_codegen_sysroot(backend_name: &str) -> fn() -> Box<dyn CodegenBackend
  let libdir = filesearch::relative_target_lib_path(&sysroot, &target);
  sysroot.join(libdir).with_file_name("codegen-backends")
  })
- .filter(|f| {
+ .find(|f| {
  info!("codegen backend candidate: {}", f.display());
  f.exists()
- })
- .next();
+ });
  let sysroot = sysroot.unwrap_or_else(|| {
  let candidates = sysroot_candidates
  .iter()

compiler/rustc_middle/src/middle/stability.rs

@@ -399,7 +399,7 @@ impl<'tcx> TyCtxt<'tcx> {
  def_id: DefId,
  id: Option<HirId>,
  span: Span,
- unmarked: impl FnOnce(Span, DefId) -> (),
+ unmarked: impl FnOnce(Span, DefId),
  ) {
  let soft_handler = |lint, span, msg: &_| {
  self.struct_span_lint_hir(lint, id.unwrap_or(hir::CRATE_HIR_ID), span, |lint| {

compiler/rustc_middle/src/mir/terminator.rs

@@ -46,7 +46,7 @@ impl SwitchTargets {
  pub fn new(targets: impl Iterator<Item = (u128, BasicBlock)>, otherwise: BasicBlock) -> Self {
  let (values, mut targets): (SmallVec<_>, SmallVec<_>) = targets.unzip();
  targets.push(otherwise);
- Self { values: values.into(), targets }
+ Self { values, targets }
  }
 
  /// Builds a switch targets definition that jumps to `then` if the tested value equals `value`,

compiler/rustc_middle/src/ty/mod.rs

@@ -1641,7 +1641,7 @@ pub type PlaceholderConst = Placeholder<BoundVar>;
 #[derive(Hash, HashStable)]
 pub struct WithOptConstParam<T> {
  pub did: T,
- /// The `DefId` of the corresponding generic paramter in case `did` is
+ /// The `DefId` of the corresponding generic parameter in case `did` is
  /// a const argument.
  ///
  /// Note that even if `did` is a const argument, this may still be `None`.

compiler/rustc_mir/src/borrow_check/diagnostics/conflict_errors.rs

@@ -120,7 +120,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
  let move_out = self.move_data.moves[(*move_site).moi];
  let moved_place = &self.move_data.move_paths[move_out.path].place;
  // `*(_1)` where `_1` is a `Box` is actually a move out.
- let is_box_move = moved_place.as_ref().projection == &[ProjectionElem::Deref]
+ let is_box_move = moved_place.as_ref().projection == [ProjectionElem::Deref]
  && self.body.local_decls[moved_place.local].ty.is_box();
 
  !is_box_move

compiler/rustc_mir/src/transform/match_branches.rs

@@ -63,7 +63,7 @@ impl<'tcx> MirPass<'tcx> for MatchBranchSimplification {
  };
 
  // Check that destinations are identical, and if not, then don't optimize this block
- if &bbs[first].terminator().kind != &bbs[second].terminator().kind {
+ if bbs[first].terminator().kind != bbs[second].terminator().kind {
  continue;
  }
 

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -1886,9 +1886,8 @@ impl<'tcx> LifetimeContext<'_, 'tcx> {
  if snippet.starts_with('&') && !snippet.starts_with("&'") {
  introduce_suggestion
  .push((param.span, format!("&'a {}", &snippet[1..])));
- } else if snippet.starts_with("&'_ ") {
- introduce_suggestion
- .push((param.span, format!("&'a {}", &snippet[4..])));
+ } else if let Some(stripped) = snippet.strip_prefix("&'_ ") {
+ introduce_suggestion.push((param.span, format!("&'a {}", &stripped)));
  }
  }
  }

compiler/rustc_span/src/lib.rs

@@ -1574,7 +1574,7 @@ fn normalize_src(src: &mut String, start_pos: BytePos) -> Vec<NormalizedPos> {
 
 /// Removes UTF-8 BOM, if any.
 fn remove_bom(src: &mut String, normalized_pos: &mut Vec<NormalizedPos>) {
- if src.starts_with("\u{feff}") {
+ if src.starts_with('\u{feff}') {
  src.drain(..3);
  normalized_pos.push(NormalizedPos { pos: BytePos(0), diff: 3 });
  }

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

@@ -1388,11 +1388,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
  trait_ref: &ty::PolyTraitRef<'tcx>,
  ) {
  let get_trait_impl = |trait_def_id| {
- self.tcx.find_map_relevant_impl(
- trait_def_id,
- trait_ref.skip_binder().self_ty(),
- |impl_def_id| Some(impl_def_id),
- )
+ self.tcx.find_map_relevant_impl(trait_def_id, trait_ref.skip_binder().self_ty(), Some)
  };
  let required_trait_path = self.tcx.def_path_str(trait_ref.def_id());
  let all_traits = self.tcx.all_traits(LOCAL_CRATE);

compiler/rustc_trait_selection/src/traits/fulfill.rs

@@ -499,7 +499,7 @@ impl<'a, 'b, 'tcx> FulfillProcessor<'a, 'b, 'tcx> {
  Err(ErrorHandled::TooGeneric) => {
  pending_obligation.stalled_on = substs
  .iter()
- .filter_map(|ty| TyOrConstInferVar::maybe_from_generic_arg(ty))
+ .filter_map(TyOrConstInferVar::maybe_from_generic_arg)
  .collect();
  ProcessResult::Unchanged
  }

library/alloc/tests/slice.rs

@@ -1,5 +1,6 @@
 use std::cell::Cell;
 use std::cmp::Ordering::{self, Equal, Greater, Less};
+use std::convert::identity;
 use std::mem;
 use std::panic;
 use std::rc::Rc;
@@ -1778,3 +1779,122 @@ fn repeat_generic_slice() {
  assert_eq!([1, 2, 3, 4].repeat(1), vec![1, 2, 3, 4]);
  assert_eq!([1, 2, 3, 4].repeat(3), vec![1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4]);
 }
+
+#[test]
+#[allow(unreachable_patterns)]
+fn subslice_patterns() {
+ // This test comprehensively checks the passing static and dynamic semantics
+ // of subslice patterns `..`, `x @ ..`, `ref x @ ..`, and `ref mut @ ..`
+ // in slice patterns `[$($pat), $(,)?]` .
+
+ #[derive(PartialEq, Debug, Clone)]
+ struct N(u8);
+
+ macro_rules! n {
+ ($($e:expr),* $(,)?) => {
+ [$(N($e)),*]
+ }
+ }
+
+ macro_rules! c {
+ ($inp:expr, $typ:ty, $out:expr $(,)?) => {
+ assert_eq!($out, identity::<$typ>($inp));
+ };
+ }
+
+ macro_rules! m {
+ ($e:expr, $p:pat => $b:expr) => {
+ match $e {
+ $p => $b,
+ _ => panic!(),
+ }
+ };
+ }
+
+ // == Slices ==
+
+ // Matching slices using `ref` patterns:
+ let mut v = vec![N(0), N(1), N(2), N(3), N(4)];
+ let mut vc = (0..=4).collect::<Vec<u8>>();
+
+ let [..] = v[..]; // Always matches.
+ m!(v[..], [N(0), ref sub @ .., N(4)] => c!(sub, &[N], n![1, 2, 3]));
+ m!(v[..], [N(0), ref sub @ ..] => c!(sub, &[N], n![1, 2, 3, 4]));
+ m!(v[..], [ref sub @ .., N(4)] => c!(sub, &[N], n![0, 1, 2, 3]));
+ m!(v[..], [ref sub @ .., _, _, _, _, _] => c!(sub, &[N], &n![] as &[N]));
+ m!(v[..], [_, _, _, _, _, ref sub @ ..] => c!(sub, &[N], &n![] as &[N]));
+ m!(vc[..], [x, .., y] => c!((x, y), (u8, u8), (0, 4)));
+
+ // Matching slices using `ref mut` patterns:
+ let [..] = v[..]; // Always matches.
+ m!(v[..], [N(0), ref mut sub @ .., N(4)] => c!(sub, &mut [N], n![1, 2, 3]));
+ m!(v[..], [N(0), ref mut sub @ ..] => c!(sub, &mut [N], n![1, 2, 3, 4]));
+ m!(v[..], [ref mut sub @ .., N(4)] => c!(sub, &mut [N], n![0, 1, 2, 3]));
+ m!(v[..], [ref mut sub @ .., _, _, _, _, _] => c!(sub, &mut [N], &mut n![] as &mut [N]));
+ m!(v[..], [_, _, _, _, _, ref mut sub @ ..] => c!(sub, &mut [N], &mut n![] as &mut [N]));
+ m!(vc[..], [x, .., y] => c!((x, y), (u8, u8), (0, 4)));
+
+ // Matching slices using default binding modes (&):
+ let [..] = &v[..]; // Always matches.
+ m!(&v[..], [N(0), sub @ .., N(4)] => c!(sub, &[N], n![1, 2, 3]));
+ m!(&v[..], [N(0), sub @ ..] => c!(sub, &[N], n![1, 2, 3, 4]));
+ m!(&v[..], [sub @ .., N(4)] => c!(sub, &[N], n![0, 1, 2, 3]));
+ m!(&v[..], [sub @ .., _, _, _, _, _] => c!(sub, &[N], &n![] as &[N]));
+ m!(&v[..], [_, _, _, _, _, sub @ ..] => c!(sub, &[N], &n![] as &[N]));
+ m!(&vc[..], [x, .., y] => c!((x, y), (&u8, &u8), (&0, &4)));
+
+ // Matching slices using default binding modes (&mut):
+ let [..] = &mut v[..]; // Always matches.
+ m!(&mut v[..], [N(0), sub @ .., N(4)] => c!(sub, &mut [N], n![1, 2, 3]));
+ m!(&mut v[..], [N(0), sub @ ..] => c!(sub, &mut [N], n![1, 2, 3, 4]));
+ m!(&mut v[..], [sub @ .., N(4)] => c!(sub, &mut [N], n![0, 1, 2, 3]));
+ m!(&mut v[..], [sub @ .., _, _, _, _, _] => c!(sub, &mut [N], &mut n![] as &mut [N]));
+ m!(&mut v[..], [_, _, _, _, _, sub @ ..] => c!(sub, &mut [N], &mut n![] as &mut [N]));
+ m!(&mut vc[..], [x, .., y] => c!((x, y), (&mut u8, &mut u8), (&mut 0, &mut 4)));
+
+ // == Arrays ==
+ let mut v = n![0, 1, 2, 3, 4];
+ let vc = [0, 1, 2, 3, 4];
+
+ // Matching arrays by value:
+ m!(v.clone(), [N(0), sub @ .., N(4)] => c!(sub, [N; 3], n![1, 2, 3]));
+ m!(v.clone(), [N(0), sub @ ..] => c!(sub, [N; 4], n![1, 2, 3, 4]));
+ m!(v.clone(), [sub @ .., N(4)] => c!(sub, [N; 4], n![0, 1, 2, 3]));
+ m!(v.clone(), [sub @ .., _, _, _, _, _] => c!(sub, [N; 0], n![] as [N; 0]));
+ m!(v.clone(), [_, _, _, _, _, sub @ ..] => c!(sub, [N; 0], n![] as [N; 0]));
+ m!(v.clone(), [x, .., y] => c!((x, y), (N, N), (N(0), N(4))));
+ m!(v.clone(), [..] => ());
+
+ // Matching arrays by ref patterns:
+ m!(v, [N(0), ref sub @ .., N(4)] => c!(sub, &[N; 3], &n![1, 2, 3]));
+ m!(v, [N(0), ref sub @ ..] => c!(sub, &[N; 4], &n![1, 2, 3, 4]));
+ m!(v, [ref sub @ .., N(4)] => c!(sub, &[N; 4], &n![0, 1, 2, 3]));
+ m!(v, [ref sub @ .., _, _, _, _, _] => c!(sub, &[N; 0], &n![] as &[N; 0]));
+ m!(v, [_, _, _, _, _, ref sub @ ..] => c!(sub, &[N; 0], &n![] as &[N; 0]));
+ m!(vc, [x, .., y] => c!((x, y), (u8, u8), (0, 4)));
+
+ // Matching arrays by ref mut patterns:
+ m!(v, [N(0), ref mut sub @ .., N(4)] => c!(sub, &mut [N; 3], &mut n![1, 2, 3]));
+ m!(v, [N(0), ref mut sub @ ..] => c!(sub, &mut [N; 4], &mut n![1, 2, 3, 4]));
+ m!(v, [ref mut sub @ .., N(4)] => c!(sub, &mut [N; 4], &mut n![0, 1, 2, 3]));
+ m!(v, [ref mut sub @ .., _, _, _, _, _] => c!(sub, &mut [N; 0], &mut n![] as &mut [N; 0]));
+ m!(v, [_, _, _, _, _, ref mut sub @ ..] => c!(sub, &mut [N; 0], &mut n![] as &mut [N; 0]));
+
+ // Matching arrays by default binding modes (&):
+ m!(&v, [N(0), sub @ .., N(4)] => c!(sub, &[N; 3], &n![1, 2, 3]));
+ m!(&v, [N(0), sub @ ..] => c!(sub, &[N; 4], &n![1, 2, 3, 4]));
+ m!(&v, [sub @ .., N(4)] => c!(sub, &[N; 4], &n![0, 1, 2, 3]));
+ m!(&v, [sub @ .., _, _, _, _, _] => c!(sub, &[N; 0], &n![] as &[N; 0]));
+ m!(&v, [_, _, _, _, _, sub @ ..] => c!(sub, &[N; 0], &n![] as &[N; 0]));
+ m!(&v, [..] => ());
+ m!(&v, [x, .., y] => c!((x, y), (&N, &N), (&N(0), &N(4))));
+
+ // Matching arrays by default binding modes (&mut):
+ m!(&mut v, [N(0), sub @ .., N(4)] => c!(sub, &mut [N; 3], &mut n![1, 2, 3]));
+ m!(&mut v, [N(0), sub @ ..] => c!(sub, &mut [N; 4], &mut n![1, 2, 3, 4]));
+ m!(&mut v, [sub @ .., N(4)] => c!(sub, &mut [N; 4], &mut n![0, 1, 2, 3]));
+ m!(&mut v, [sub @ .., _, _, _, _, _] => c!(sub, &mut [N; 0], &mut n![] as &[N; 0]));
+ m!(&mut v, [_, _, _, _, _, sub @ ..] => c!(sub, &mut [N; 0], &mut n![] as &[N; 0]));
+ m!(&mut v, [..] => ());
+ m!(&mut v, [x, .., y] => c!((x, y), (&mut N, &mut N), (&mut N(0), &mut N(4))));
+}

library/alloc/tests/vec.rs

@@ -3,7 +3,7 @@ use std::cell::Cell;
 use std::collections::TryReserveError::*;
 use std::fmt::Debug;
 use std::iter::InPlaceIterable;
-use std::mem::size_of;
+use std::mem::{size_of, swap};
 use std::ops::Bound::*;
 use std::panic::{catch_unwind, AssertUnwindSafe};
 use std::rc::Rc;
@@ -1912,3 +1912,45 @@ fn test_vec_cycle_wrapped() {
  c3.refs.v[0].set(Some(&c1));
  c3.refs.v[1].set(Some(&c2));
 }
+
+#[test]
+fn test_zero_sized_vec_push() {
+ const N: usize = 8;
+
+ for len in 0..N {
+ let mut tester = Vec::with_capacity(len);
+ assert_eq!(tester.len(), 0);
+ assert!(tester.capacity() >= len);
+ for _ in 0..len {
+ tester.push(());
+ }
+ assert_eq!(tester.len(), len);
+ assert_eq!(tester.iter().count(), len);
+ tester.clear();
+ }
+}
+
+#[test]
+fn test_vec_macro_repeat() {
+ assert_eq!(vec![1; 3], vec![1, 1, 1]);
+ assert_eq!(vec![1; 2], vec![1, 1]);
+ assert_eq!(vec![1; 1], vec![1]);
+ assert_eq!(vec![1; 0], vec![]);
+
+ // from_elem syntax (see RFC 832)
+ let el = Box::new(1);
+ let n = 3;
+ assert_eq!(vec![el; n], vec![Box::new(1), Box::new(1), Box::new(1)]);
+}
+
+#[test]
+fn test_vec_swap() {
+ let mut a: Vec<isize> = vec![0, 1, 2, 3, 4, 5, 6];
+ a.swap(2, 4);
+ assert_eq!(a[2], 4);
+ assert_eq!(a[4], 2);
+ let mut n = 42;
+ swap(&mut n, &mut a[0]);
+ assert_eq!(a[0], 42);
+ assert_eq!(n, 0);
+}

library/alloc/tests/vec_deque.rs

@@ -1698,3 +1698,33 @@ fn test_binary_search_by_key() {
  assert_eq!(deque.binary_search_by_key(&3, |&(v,)| v), Ok(2));
  assert_eq!(deque.binary_search_by_key(&4, |&(v,)| v), Err(3));
 }
+
+#[test]
+fn test_zero_sized_push() {
+ const N: usize = 8;
+
+ // Zero sized type
+ struct Zst;
+
+ // Test that for all possible sequences of push_front / push_back,
+ // we end up with a deque of the correct size
+
+ for len in 0..N {
+ let mut tester = VecDeque::with_capacity(len);
+ assert_eq!(tester.len(), 0);
+ assert!(tester.capacity() >= len);
+ for case in 0..(1 << len) {
+ assert_eq!(tester.len(), 0);
+ for bit in 0..len {
+ if case & (1 << bit) != 0 {
+ tester.push_front(Zst);
+ } else {
+ tester.push_back(Zst);
+ }
+ }
+ assert_eq!(tester.len(), len);
+ assert_eq!(tester.iter().count(), len);
+ tester.clear();
+ }
+ }
+}

library/core/src/array/mod.rs

@@ -353,8 +353,9 @@ impl<T: Ord, const N: usize> Ord for [T; N] {
  }
 }
 
-// The Default impls cannot be generated using the array_impls! macro because
-// they require array literals.
+// The Default impls cannot be done with const generics because `[T; 0]` doesn't
+// require Default to be implemented, and having different impl blocks for
+// different numbers isn't supported yet.
 
 macro_rules! array_impl_default {
  {$n:expr, $t:ident $($ts:ident)*} => {

library/core/src/cell.rs

@@ -1733,8 +1733,7 @@ impl<T: ?Sized> UnsafeCell<T> {
  #[inline]
  #[unstable(feature = "unsafe_cell_get_mut", issue = "76943")]
  pub fn get_mut(&mut self) -> &mut T {
- // SAFETY: (outer) `&mut` guarantees unique access.
- unsafe { &mut *self.get() }
+ &mut self.value
  }
 
  /// Gets a mutable pointer to the wrapped value.