Auto merge of #66009 - tmandry:rollup-jt3wtfr, r=tmandry

Rollup of 14 pull requests

Successful merges:

 - #65112 (Add lint and tests for unnecessary parens around types)
 - #65459 (Fix `-Zunpretty=mir-cfg` to render multiple items)
 - #65471 (Add long error explanation for E0578)
 - #65857 (rustdoc: Resolve module-level doc references more locally)
 - #65914 (Use structured suggestion for unnecessary bounds in type aliases)
 - #65945 (Optimize long-linker-command-line test)
 - #65946 (Make `promote_consts` emit the errors when required promotion fails)
 - #65960 (doc: reword iter module example and mention other methods)
 - #65963 (update submodules to rust-lang)
 - #65972 (Fix libunwind build: Define __LITTLE_ENDIAN__ for LE targets)
 - #65977 (Fix incorrect diagnostics for expected type in E0271 with an associated type)
 - #65995 (Add error code E0743 for "C-variadic has been used on a non-foreign function")
 - #65997 (Fix outdated rustdoc of Once::init_locking function)
 - #66005 (vxWorks: remove code related unix socket)

Failed merges:

r? @ghost

Author: bors

.gitmodules

@@ -3,13 +3,13 @@
 	url = https://github.com/rust-lang/rust-installer.git
 [submodule "src/doc/nomicon"]
 	path = src/doc/nomicon
-	url = https://github.com/rust-lang-nursery/nomicon.git
+	url = https://github.com/rust-lang/nomicon.git
 [submodule "src/tools/cargo"]
 	path = src/tools/cargo
 	url = https://github.com/rust-lang/cargo.git
 [submodule "src/doc/reference"]
 	path = src/doc/reference
-	url = https://github.com/rust-lang-nursery/reference.git
+	url = https://github.com/rust-lang/reference.git
 [submodule "src/doc/book"]
 	path = src/doc/book
 	url = https://github.com/rust-lang/book.git
@@ -36,7 +36,7 @@
 	url = https://github.com/rust-lang/rustc-guide.git
 [submodule "src/doc/edition-guide"]
 	path = src/doc/edition-guide
-	url = https://github.com/rust-lang-nursery/edition-guide.git
+	url = https://github.com/rust-lang/edition-guide.git
 [submodule "src/llvm-project"]
 	path = src/llvm-project
 	url = https://github.com/rust-lang/llvm-project.git

src/libcore/iter/mod.rs

@@ -118,26 +118,16 @@
 //!
 //! let mut counter = Counter::new();
 //!
-//! let x = counter.next().unwrap();
-//! println!("{}", x);
-//!
-//! let x = counter.next().unwrap();
-//! println!("{}", x);
-//!
-//! let x = counter.next().unwrap();
-//! println!("{}", x);
-//!
-//! let x = counter.next().unwrap();
-//! println!("{}", x);
-//!
-//! let x = counter.next().unwrap();
-//! println!("{}", x);
+//! assert_eq!(counter.next(), Some(1));
+//! assert_eq!(counter.next(), Some(2));
+//! assert_eq!(counter.next(), Some(3));
+//! assert_eq!(counter.next(), Some(4));
+//! assert_eq!(counter.next(), Some(5));
+//! assert_eq!(counter.next(), None);
 //! ```
 //!
-//! This will print `1` through `5`, each on their own line.
-//!
-//! Calling `next()` this way gets repetitive. Rust has a construct which can
-//! call `next()` on your iterator, until it reaches `None`. Let's go over that
+//! Calling [`next`] this way gets repetitive. Rust has a construct which can
+//! call [`next`] on your iterator, until it reaches `None`. Let's go over that
 //! next.
 //!
 //! Also note that `Iterator` provides a default implementation of methods such as `nth` and `fold`
@@ -253,20 +243,23 @@
 //! ```
 //!
 //! The idiomatic way to write a [`map`] for its side effects is to use a
-//! `for` loop instead:
+//! `for` loop or call the [`for_each`] method:
 //!
 //! ```
 //! let v = vec![1, 2, 3, 4, 5];
 //!
+//! v.iter().for_each(|x| println!("{}", x));
+//! // or
 //! for x in &v {
 //!     println!("{}", x);
 //! }
 //! ```
 //!
 //! [`map`]: trait.Iterator.html#method.map
+//! [`for_each`]: trait.Iterator.html#method.for_each
 //!
-//! The two most common ways to evaluate an iterator are to use a `for` loop
-//! like this, or using the [`collect`] method to produce a new collection.
+//! Another common way to evaluate an iterator is to use the [`collect`]
+//! method to produce a new collection.
 //!
 //! [`collect`]: trait.Iterator.html#method.collect
 //!

src/librustc/infer/error_reporting/nice_region_error/find_anon_type.rs

@@ -62,7 +62,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
         &self,
         arg: &'tcx hir::Ty,
         br: &ty::BoundRegion,
-    ) -> Option<(&'tcx hir::Ty)> {
+    ) -> Option<&'tcx hir::Ty> {
         let mut nested_visitor = FindNestedTypeVisitor {
             tcx: self.tcx(),
             bound_region: *br,

src/librustc/traits/error_reporting.rs

@@ -226,13 +226,26 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                     0,
                     &mut obligations
                 );
+
+                debug!("report_projection_error obligation.cause={:?} obligation.param_env={:?}",
+                       obligation.cause, obligation.param_env);
+
+                debug!("report_projection_error normalized_ty={:?} data.ty={:?}",
+                       normalized_ty, data.ty);
+
+                let is_normalized_ty_expected = match &obligation.cause.code {
+                    ObligationCauseCode::ItemObligation(_) |
+                    ObligationCauseCode::BindingObligation(_, _) |
+                    ObligationCauseCode::ObjectCastObligation(_) => false,
+                    _ => true,
+                };
+
                 if let Err(error) = self.at(&obligation.cause, obligation.param_env)
-                    .eq(normalized_ty, data.ty)
+                    .eq_exp(is_normalized_ty_expected, normalized_ty, data.ty)
                 {
-                    values = Some(infer::ValuePairs::Types(ExpectedFound {
-                        expected: normalized_ty,
-                        found: data.ty,
-                    }));
+                    values = Some(infer::ValuePairs::Types(
+                        ExpectedFound::new(is_normalized_ty_expected, normalized_ty, data.ty)));
+
                     err_buf = error;
                     err = &err_buf;
                 }

src/librustc_data_structures/owning_ref/mod.rs

@@ -1046,14 +1046,14 @@ unsafe impl<O, T: ?Sized> CloneStableAddress for OwningRef<O, T>
     where O: CloneStableAddress {}
 
 unsafe impl<O, T: ?Sized> Send for OwningRef<O, T>
-    where O: Send, for<'a> (&'a T): Send {}
+    where O: Send, for<'a> &'a T: Send {}
 unsafe impl<O, T: ?Sized> Sync for OwningRef<O, T>
-    where O: Sync, for<'a> (&'a T): Sync {}
+    where O: Sync, for<'a> &'a T: Sync {}
 
 unsafe impl<O, T: ?Sized> Send for OwningRefMut<O, T>
-    where O: Send, for<'a> (&'a mut T): Send {}
+    where O: Send, for<'a> &'a mut T: Send {}
 unsafe impl<O, T: ?Sized> Sync for OwningRefMut<O, T>
-    where O: Sync, for<'a> (&'a mut T): Sync {}
+    where O: Sync, for<'a> &'a mut T: Sync {}
 
 impl Debug for dyn Erased {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {

src/librustc_data_structures/sync.rs

@@ -492,10 +492,10 @@ impl<T> Once<T> {
         assert!(self.try_set(value).is_none());
     }
 
-    /// Tries to initialize the inner value by calling the closure while ensuring that no-one else
-    /// can access the value in the mean time by holding a lock for the duration of the closure.
-    /// If the value was already initialized the closure is not called and `false` is returned,
-    /// otherwise if the value from the closure initializes the inner value, `true` is returned
+    /// Initializes the inner value if it wasn't already done by calling the provided closure. It
+    /// ensures that no-one else can access the value in the mean time by holding a lock for the
+    /// duration of the closure.
+    /// A reference to the inner value is returned.
     #[inline]
     pub fn init_locking<F: FnOnce() -> T>(&self, f: F) -> &T {
         {

src/librustc_lint/builtin.rs

@@ -1125,8 +1125,12 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeAliasBounds {
                 .map(|pred| pred.span()).collect();
             let mut err = cx.struct_span_lint(TYPE_ALIAS_BOUNDS, spans,
                 "where clauses are not enforced in type aliases");
-            err.help("the clause will not be checked when the type alias is used, \
-                      and should be removed");
+            err.span_suggestion(
+                type_alias_generics.where_clause.span_for_predicates_or_empty_place(),
+                "the clause will not be checked when the type alias is used, and should be removed",
+                String::new(),
+                Applicability::MachineApplicable,
+            );
             if !suggested_changing_assoc_types {
                 TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
                 suggested_changing_assoc_types = true;
@@ -1136,14 +1140,19 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeAliasBounds {
         // The parameters must not have bounds
         for param in type_alias_generics.params.iter() {
             let spans: Vec<_> = param.bounds.iter().map(|b| b.span()).collect();
+            let suggestion = spans.iter().map(|sp| {
+                let start = param.span.between(*sp); // Include the `:` in `T: Bound`.
+                (start.to(*sp), String::new())
+            }).collect();
             if !spans.is_empty() {
                 let mut err = cx.struct_span_lint(
                     TYPE_ALIAS_BOUNDS,
                     spans,
                     "bounds on generic parameters are not enforced in type aliases",
                 );
-                err.help("the bound will not be checked when the type alias is used, \
-                          and should be removed");
+                let msg = "the bound will not be checked when the type alias is used, \
+                           and should be removed";
+                err.multipart_suggestion(&msg, suggestion, Applicability::MachineApplicable);
                 if !suggested_changing_assoc_types {
                     TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
                     suggested_changing_assoc_types = true;

src/librustc_lint/unused.rs

@@ -598,6 +598,25 @@ impl EarlyLintPass for UnusedParens {
     fn check_arm(&mut self, cx: &EarlyContext<'_>, arm: &ast::Arm) {
         self.check_unused_parens_pat(cx, &arm.pat, false, false);
     }
+
+    fn check_ty(&mut self, cx: &EarlyContext<'_>, ty: &ast::Ty) {
+        if let &ast::TyKind::Paren(ref r) = &ty.kind {
+            match &r.kind {
+                &ast::TyKind::TraitObject(..) => {}
+                &ast::TyKind::ImplTrait(_, ref bounds) if bounds.len() > 1 => {}
+                _ => {
+                    let pattern_text = if let Ok(snippet) = cx.sess().source_map()
+                        .span_to_snippet(ty.span) {
+                            snippet
+                        } else {
+                            pprust::ty_to_string(ty)
+                        };
+
+                    Self::remove_outer_parens(cx, ty.span, &pattern_text, "type", (false, false));
+                }
+            }
+        }
+    }
 }
 
 declare_lint! {

src/librustc_mir/borrow_check/prefixes.rs

@@ -29,7 +29,7 @@ pub(super) struct Prefixes<'cx, 'tcx> {
     body: &'cx Body<'tcx>,
     tcx: TyCtxt<'tcx>,
     kind: PrefixSet,
-    next: Option<(PlaceRef<'cx, 'tcx>)>,
+    next: Option<PlaceRef<'cx, 'tcx>>,
 }
 
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]

src/librustc_mir/error_codes.rs

@@ -2545,7 +2545,7 @@ There are some known bugs that trigger this message.
 //  E0471, // constant evaluation error (in pattern)
 //  E0385, // {} in an aliasable location
     E0521, // borrowed data escapes outside of closure
-    E0526, // shuffle indices are not constant
+//  E0526, // shuffle indices are not constant
     E0594, // cannot assign to {}
 //  E0598, // lifetime of {} is too short to guarantee its contents can be...
     E0625, // thread-local statics cannot be accessed at compile-time

src/librustc_mir/transform/promote_consts.rs

@@ -80,6 +80,17 @@ pub enum Candidate {
     Argument { bb: BasicBlock, index: usize },
 }
 
+impl Candidate {
+    /// Returns `true` if we should use the "explicit" rules for promotability for this `Candidate`.
+    fn forces_explicit_promotion(&self) -> bool {
+        match self {
+            Candidate::Ref(_) |
+            Candidate::Repeat(_) => false,
+            Candidate::Argument { .. } => true,
+        }
+    }
+}
+
 fn args_required_const(tcx: TyCtxt<'_>, def_id: DefId) -> Option<Vec<usize>> {
     let attrs = tcx.get_attrs(def_id);
     let attr = attrs.iter().find(|a| a.check_name(sym::rustc_args_required_const))?;
@@ -727,16 +738,22 @@ pub fn validate_candidates(
     };
 
     candidates.iter().copied().filter(|&candidate| {
-        validator.explicit = match candidate {
-            Candidate::Ref(_) |
-            Candidate::Repeat(_) => false,
-            Candidate::Argument { .. } => true,
-        };
+        validator.explicit = candidate.forces_explicit_promotion();
 
         // FIXME(eddyb) also emit the errors for shuffle indices
         // and `#[rustc_args_required_const]` arguments here.
 
-        validator.validate_candidate(candidate).is_ok()
+        let is_promotable = validator.validate_candidate(candidate).is_ok();
+        match candidate {
+            Candidate::Argument { bb, index } if !is_promotable => {
+                let span = body[bb].terminator().source_info.span;
+                let msg = format!("argument {} is required to be a constant", index + 1);
+                tcx.sess.span_err(span, &msg);
+            }
+            _ => ()
+        }
+
+        is_promotable
     }).collect()
 }
 

src/librustc_mir/transform/qualify_consts.rs

@@ -1606,20 +1606,12 @@ impl<'a, 'tcx> Visitor<'tcx> for Checker<'a, 'tcx> {
                     // This is not a problem, because the argument explicitly
                     // requests constness, in contrast to regular promotion
                     // which happens even without the user requesting it.
-                    // We can error out with a hard error if the argument is not
-                    // constant here.
+                    //
+                    // `promote_consts` is responsible for emitting the error if
+                    // the argument is not promotable.
                     if !IsNotPromotable::in_operand(self, arg) {
                         debug!("visit_terminator_kind: candidate={:?}", candidate);
                         self.promotion_candidates.push(candidate);
-                    } else {
-                        if is_shuffle {
-                            span_err!(self.tcx.sess, self.span, E0526,
-                                      "shuffle indices are not constant");
-                        } else {
-                            self.tcx.sess.span_err(self.span,
-                                &format!("argument {} is required to be a constant",
-                                         i + 1));
-                        }
                     }
                 }
             }