Auto merge of #72054 - Mark-Simulacrum:beta-next, r=Mark-Simulacrum

[beta] backports

This backport rollup includes the following:
 * [beta] Update cargo #71967
 * Backport 1.43.1 release notes to master #71914
 * Update the `cc` crate #71882
 * resolve: Relax fresh binding disambiguation slightly to fix regression #71846
 * Do not try to find binop method on RHS `TyErr` #71810
 * Quick and dirty fix of the unused_braces lint #71517
 * Update stdarch submodule #71495
 * normalize field projection ty to fix broken MIR issue #71488
 * Update openssl-src to 1.1.1g #71430
 * fix error code in E0751.md #71426
 * Don't fuse Chain in its second iterator #71404
 * Remove some `Vec` allocations to improve performance #71268
 * [CI] Use the latest Python available on Windows #71995

It also switches the bootstrap compiler to 1.43.1.

Cargo.lock

@@ -412,9 +412,9 @@ version = "0.1.0"
 
 [[package]]
 name = "cc"
-version = "1.0.50"
+version = "1.0.52"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "95e28fa049fda1c330bcf9d723be7663a899c4679724b34c81e9f5a326aab8cd"
+checksum = "c3d87b23d6a92cd03af510a5ade527033f6aa6fa92161e2d5863a907d4c5e31d"
 dependencies = [
  "jobserver",
 ]
@@ -2298,9 +2298,9 @@ checksum = "77af24da69f9d9341038eba93a073b1fdaaa1b788221b00a69bce9e762cb32de"
 
 [[package]]
 name = "openssl-src"
-version = "111.8.1+1.1.1f"
+version = "111.9.0+1.1.1g"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f04f0299a91de598dde58d2e99101895498dcf3d58896a3297798f28b27c8b72"
+checksum = "a2dbe10ddd1eb335aba3780eb2eaa13e1b7b441d2562fd962398740927f39ec4"
 dependencies = [
  "cc",
 ]

RELEASES.md

@@ -1,3 +1,15 @@
+Version 1.43.1 (2020-05-07)
+===========================
+
+* [Updated openssl-src to 1.1.1g for CVE-2020-1967.][71430]
+* [Fixed the stabilization of AVX-512 features.][71473]
+* [Fixed `cargo package --list` not working with unpublished dependencies.][cargo/8151]
+
+[71430]: https://github.com/rust-lang/rust/pull/71430
+[71473]: https://github.com/rust-lang/rust/issues/71473
+[cargo/8151]: https://github.com/rust-lang/cargo/issues/8151
+
+
 Version 1.43.0 (2020-04-23)
 ==========================
 
@@ -14,7 +26,7 @@ Language
 - [Merge `fn` syntax + cleanup item parsing.][68728]
 - [`item` macro fragments can be interpolated into `trait`s, `impl`s, and `extern` blocks.][69366]
   For example, you may now write:
-  ```rust 
+  ```rust
   macro_rules! mac_trait {
       ($i:item) => {
           trait T { $i }
@@ -82,7 +94,7 @@ Misc
 - [Certain checks in the `const_err` lint were deemed unrelated to const
   evaluation][69185], and have been moved to the `unconditional_panic` and
   `arithmetic_overflow` lints.
-  
+
 Compatibility Notes
 -------------------
 
@@ -173,7 +185,7 @@ Language
      (e.g. `type Foo: Ord;`).
    - `...` (the C-variadic type) may occur syntactically directly as the type of
       any function parameter.
-  
+
   These are still rejected *semantically*, so you will likely receive an error
   but these changes can be seen and parsed by procedural macros and
   conditional compilation.
@@ -465,7 +477,7 @@ Compatibility Notes
 - [Using `#[inline]` on function prototypes and consts now emits a warning under
   `unused_attribute` lint.][65294] Using `#[inline]` anywhere else inside traits
   or `extern` blocks now correctly emits a hard error.
-  
+
 [65294]: https://github.com/rust-lang/rust/pull/65294/
 [66103]: https://github.com/rust-lang/rust/pull/66103/
 [65843]: https://github.com/rust-lang/rust/pull/65843/

src/ci/scripts/install-msys2-packages.sh

@@ -9,11 +9,19 @@ if isWindows; then
     pacman -S --noconfirm --needed base-devel ca-certificates make diffutils tar \
         binutils
 
+    # Detect the native Python version installed on the agent. On GitHub
+    # Actions, the C:\hostedtoolcache\windows\Python directory contains a
+    # subdirectory for each installed Python version.
+    #
+    # The -V flag of the sort command sorts the input by version number.
+    native_python_version="$(ls /c/hostedtoolcache/windows/Python | sort -Vr | head -n 1)"
+
     # Make sure we use the native python interpreter instead of some msys equivalent
     # one way or another. The msys interpreters seem to have weird path conversions
     # baked in which break LLVM's build system one way or another, so let's use the
     # native version which keeps everything as native as possible.
-    python_home="C:/hostedtoolcache/windows/Python/3.7.6/x64"
+    python_home="/c/hostedtoolcache/windows/Python/${native_python_version}/x64"
     cp "${python_home}/python.exe" "${python_home}/python3.exe"
-    ciCommandAddPath "C:\\hostedtoolcache\\windows\\Python\\3.7.6\\x64"
+    ciCommandAddPath "C:\\hostedtoolcache\\windows\\Python\\${native_python_version}\\x64"
+    ciCommandAddPath "C:\\hostedtoolcache\\windows\\Python\\${native_python_version}\\x64\\Scripts"
 fi

src/libcore/iter/adapters/chain.rs

@@ -18,6 +18,9 @@ pub struct Chain<A, B> {
     // adapter because its specialization for `FusedIterator` unconditionally descends into the
     // iterator, and that could be expensive to keep revisiting stuff like nested chains. It also
     // hurts compiler performance to add more iterator layers to `Chain`.
+    //
+    // Only the "first" iterator is actually set `None` when exhausted, depending on whether you
+    // iterate forward or backward. If you mix directions, then both sides may be `None`.
     a: Option<A>,
     b: Option<B>,
 }
@@ -43,6 +46,17 @@ macro_rules! fuse {
     };
 }
 
+/// Try an iterator method without fusing,
+/// like an inline `.as_mut().and_then(...)`
+macro_rules! maybe {
+    ($self:ident . $iter:ident . $($call:tt)+) => {
+        match $self.$iter {
+            Some(ref mut iter) => iter.$($call)+,
+            None => None,
+        }
+    };
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<A, B> Iterator for Chain<A, B>
 where
@@ -54,7 +68,7 @@ where
     #[inline]
     fn next(&mut self) -> Option<A::Item> {
         match fuse!(self.a.next()) {
-            None => fuse!(self.b.next()),
+            None => maybe!(self.b.next()),
             item => item,
         }
     }
@@ -85,7 +99,7 @@ where
         }
         if let Some(ref mut b) = self.b {
             acc = b.try_fold(acc, f)?;
-            self.b = None;
+            // we don't fuse the second iterator
         }
         Try::from_ok(acc)
     }
@@ -114,7 +128,7 @@ where
             }
             self.a = None;
         }
-        fuse!(self.b.nth(n))
+        maybe!(self.b.nth(n))
     }
 
     #[inline]
@@ -123,7 +137,7 @@ where
         P: FnMut(&Self::Item) -> bool,
     {
         match fuse!(self.a.find(&mut predicate)) {
-            None => fuse!(self.b.find(predicate)),
+            None => maybe!(self.b.find(predicate)),
             item => item,
         }
     }
@@ -174,7 +188,7 @@ where
     #[inline]
     fn next_back(&mut self) -> Option<A::Item> {
         match fuse!(self.b.next_back()) {
-            None => fuse!(self.a.next_back()),
+            None => maybe!(self.a.next_back()),
             item => item,
         }
     }
@@ -190,7 +204,7 @@ where
             }
             self.b = None;
         }
-        fuse!(self.a.nth_back(n))
+        maybe!(self.a.nth_back(n))
     }
 
     #[inline]
@@ -199,7 +213,7 @@ where
         P: FnMut(&Self::Item) -> bool,
     {
         match fuse!(self.b.rfind(&mut predicate)) {
-            None => fuse!(self.a.rfind(predicate)),
+            None => maybe!(self.a.rfind(predicate)),
             item => item,
         }
     }
@@ -216,7 +230,7 @@ where
         }
         if let Some(ref mut a) = self.a {
             acc = a.try_rfold(acc, f)?;
-            self.a = None;
+            // we don't fuse the second iterator
         }
         Try::from_ok(acc)
     }
@@ -236,8 +250,6 @@ where
 }
 
 // Note: *both* must be fused to handle double-ended iterators.
-// Now that we "fuse" both sides, we *could* implement this unconditionally,
-// but we should be cautious about committing to that in the public API.
 #[stable(feature = "fused", since = "1.26.0")]
 impl<A, B> FusedIterator for Chain<A, B>
 where

src/libcore/tests/iter.rs

@@ -207,50 +207,64 @@ fn test_iterator_chain_find() {
     assert_eq!(iter.next(), None);
 }
 
-#[test]
-fn test_iterator_chain_size_hint() {
-    struct Iter {
-        is_empty: bool,
-    }
+struct Toggle {
+    is_empty: bool,
+}
 
-    impl Iterator for Iter {
-        type Item = ();
+impl Iterator for Toggle {
+    type Item = ();
 
-        // alternates between `None` and `Some(())`
-        fn next(&mut self) -> Option<Self::Item> {
-            if self.is_empty {
-                self.is_empty = false;
-                None
-            } else {
-                self.is_empty = true;
-                Some(())
-            }
+    // alternates between `None` and `Some(())`
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.is_empty {
+            self.is_empty = false;
+            None
+        } else {
+            self.is_empty = true;
+            Some(())
         }
+    }
 
-        fn size_hint(&self) -> (usize, Option<usize>) {
-            if self.is_empty { (0, Some(0)) } else { (1, Some(1)) }
-        }
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        if self.is_empty { (0, Some(0)) } else { (1, Some(1)) }
     }
+}
 
-    impl DoubleEndedIterator for Iter {
-        fn next_back(&mut self) -> Option<Self::Item> {
-            self.next()
-        }
+impl DoubleEndedIterator for Toggle {
+    fn next_back(&mut self) -> Option<Self::Item> {
+        self.next()
     }
+}
 
+#[test]
+fn test_iterator_chain_size_hint() {
     // this chains an iterator of length 0 with an iterator of length 1,
     // so after calling `.next()` once, the iterator is empty and the
     // state is `ChainState::Back`. `.size_hint()` should now disregard
     // the size hint of the left iterator
-    let mut iter = Iter { is_empty: true }.chain(once(()));
+    let mut iter = Toggle { is_empty: true }.chain(once(()));
     assert_eq!(iter.next(), Some(()));
     assert_eq!(iter.size_hint(), (0, Some(0)));
 
-    let mut iter = once(()).chain(Iter { is_empty: true });
+    let mut iter = once(()).chain(Toggle { is_empty: true });
     assert_eq!(iter.next_back(), Some(()));
     assert_eq!(iter.size_hint(), (0, Some(0)));
 }
 
+#[test]
+fn test_iterator_chain_unfused() {
+    // Chain shouldn't be fused in its second iterator, depending on direction
+    let mut iter = NonFused::new(empty()).chain(Toggle { is_empty: true });
+    iter.next().unwrap_none();
+    iter.next().unwrap();
+    iter.next().unwrap_none();
+
+    let mut iter = Toggle { is_empty: true }.chain(NonFused::new(empty()));
+    iter.next_back().unwrap_none();
+    iter.next_back().unwrap();
+    iter.next_back().unwrap_none();
+}
+
 #[test]
 fn test_zip_nth() {
     let xs = [0, 1, 2, 4, 5];

src/libcore/tests/lib.rs

@@ -42,6 +42,7 @@
 #![feature(unwrap_infallible)]
 #![feature(leading_trailing_ones)]
 #![feature(const_forget)]
+#![feature(option_unwrap_none)]
 
 extern crate test;
 

src/librustc_error_codes/error_codes/E0751.md

@@ -2,7 +2,7 @@ There are both a positive and negative trait implementation for the same type.
 
 Erroneous code example:
 
-```compile_fail,E0748
+```compile_fail,E0751
 trait MyTrait {}
 impl MyTrait for i32 { }
 impl !MyTrait for i32 { }

src/librustc_infer/infer/outlives/verify.rs

@@ -223,7 +223,7 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> {
         // like `T` and `T::Item`. It may not work as well for things
         // like `<T as Foo<'a>>::Item`.
         let c_b = self.param_env.caller_bounds;
-        let param_bounds = self.collect_outlives_from_predicate_list(&compare_ty, c_b);
+        let param_bounds = self.collect_outlives_from_predicate_list(&compare_ty, c_b.into_iter());
 
         // Next, collect regions we scraped from the well-formedness
         // constraints in the fn signature. To do that, we walk the list
@@ -315,15 +315,12 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> {
         let tcx = self.tcx;
         let assoc_item = tcx.associated_item(assoc_item_def_id);
         let trait_def_id = assoc_item.container.assert_trait();
-        let trait_predicates =
-            tcx.predicates_of(trait_def_id).predicates.iter().map(|(p, _)| *p).collect();
+        let trait_predicates = tcx.predicates_of(trait_def_id).predicates.iter().map(|(p, _)| *p);
         let identity_substs = InternalSubsts::identity_for_item(tcx, assoc_item_def_id);
         let identity_proj = tcx.mk_projection(assoc_item_def_id, identity_substs);
         self.collect_outlives_from_predicate_list(
             move |ty| ty == identity_proj,
-            traits::elaborate_predicates(tcx, trait_predicates)
-                .map(|o| o.predicate)
-                .collect::<Vec<_>>(),
+            traits::elaborate_predicates(tcx, trait_predicates).map(|o| o.predicate),
         )
         .map(|b| b.1)
     }

src/librustc_infer/traits/util.rs

@@ -97,24 +97,22 @@ pub fn elaborate_trait_ref<'tcx>(
     tcx: TyCtxt<'tcx>,
     trait_ref: ty::PolyTraitRef<'tcx>,
 ) -> Elaborator<'tcx> {
-    elaborate_predicates(tcx, vec![trait_ref.without_const().to_predicate()])
+    elaborate_predicates(tcx, std::iter::once(trait_ref.without_const().to_predicate()))
 }
 
 pub fn elaborate_trait_refs<'tcx>(
     tcx: TyCtxt<'tcx>,
     trait_refs: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
 ) -> Elaborator<'tcx> {
-    let predicates = trait_refs.map(|trait_ref| trait_ref.without_const().to_predicate()).collect();
+    let predicates = trait_refs.map(|trait_ref| trait_ref.without_const().to_predicate());
     elaborate_predicates(tcx, predicates)
 }
 
 pub fn elaborate_predicates<'tcx>(
     tcx: TyCtxt<'tcx>,
-    mut predicates: Vec<ty::Predicate<'tcx>>,
+    predicates: impl IntoIterator<Item = ty::Predicate<'tcx>>,
 ) -> Elaborator<'tcx> {
-    let mut visited = PredicateSet::new(tcx);
-    predicates.retain(|pred| visited.insert(pred));
-    let obligations: Vec<_> =
+    let obligations =
         predicates.into_iter().map(|predicate| predicate_obligation(predicate, None)).collect();
     elaborate_obligations(tcx, obligations)
 }
@@ -151,21 +149,20 @@ impl Elaborator<'tcx> {
                 // Get predicates declared on the trait.
                 let predicates = tcx.super_predicates_of(data.def_id());
 
-                let obligations = predicates.predicates.iter().map(|(pred, span)| {
+                let obligations = predicates.predicates.into_iter().map(|(pred, span)| {
                     predicate_obligation(
                         pred.subst_supertrait(tcx, &data.to_poly_trait_ref()),
                         Some(*span),
                     )
                 });
-                debug!("super_predicates: data={:?} predicates={:?}", data, &obligations);
+                debug!("super_predicates: data={:?}", data);
 
                 // Only keep those bounds that we haven't already seen.
                 // This is necessary to prevent infinite recursion in some
                 // cases. One common case is when people define
                 // `trait Sized: Sized { }` rather than `trait Sized { }`.
                 let visited = &mut self.visited;
-                let obligations =
-                    obligations.filter(|obligation| visited.insert(&obligation.predicate));
+                let obligations = obligations.filter(|o| visited.insert(&o.predicate));
 
                 self.stack.extend(obligations);
             }