[beta] Rollup backports

src/librustc/lint/builtin.rs

@@ -386,6 +386,12 @@ declare_lint! {
     "ambiguous associated items"
 }
 
+declare_lint! {
+    pub NESTED_IMPL_TRAIT,
+    Warn,
+    "nested occurrence of `impl Trait` type"
+}
+
 /// Does nothing as a lint pass, but registers some `Lint`s
 /// that are used by other parts of the compiler.
 #[derive(Copy, Clone)]
@@ -457,6 +463,7 @@ impl LintPass for HardwiredLints {
             parser::ILL_FORMED_ATTRIBUTE_INPUT,
             DEPRECATED_IN_FUTURE,
             AMBIGUOUS_ASSOCIATED_ITEMS,
+            NESTED_IMPL_TRAIT,
         )
     }
 }
@@ -474,6 +481,7 @@ pub enum BuiltinLintDiagnostics {
     ElidedLifetimesInPaths(usize, Span, bool, Span, String),
     UnknownCrateTypes(Span, String, String),
     UnusedImports(String, Vec<(Span, String)>),
+    NestedImplTrait { outer_impl_trait_span: Span, inner_impl_trait_span: Span },
 }
 
 impl BuiltinLintDiagnostics {
@@ -564,6 +572,12 @@ impl BuiltinLintDiagnostics {
                     );
                 }
             }
+            BuiltinLintDiagnostics::NestedImplTrait {
+                outer_impl_trait_span, inner_impl_trait_span
+            } => {
+                db.span_label(outer_impl_trait_span, "outer `impl Trait`");
+                db.span_label(inner_impl_trait_span, "nested `impl Trait` here");
+            }
         }
     }
 }

src/librustc/middle/expr_use_visitor.rs

@@ -83,6 +83,9 @@ pub trait Delegate<'tcx> {
               assignment_span: Span,
               assignee_cmt: &mc::cmt_<'tcx>,
               mode: MutateMode);
+
+    // A nested closure or generator - only one layer deep.
+    fn nested_body(&mut self, _body_id: hir::BodyId) {}
 }
 
 #[derive(Copy, Clone, PartialEq, Debug)]
@@ -532,8 +535,9 @@ impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
                 self.consume_expr(&base);
             }
 
-            hir::ExprKind::Closure(.., fn_decl_span, _) => {
-                self.walk_captures(expr, fn_decl_span)
+            hir::ExprKind::Closure(_, _, body_id, fn_decl_span, _) => {
+                self.delegate.nested_body(body_id);
+                self.walk_captures(expr, fn_decl_span);
             }
 
             hir::ExprKind::Box(ref base) => {

src/librustc_borrowck/borrowck/gather_loans/mod.rs

@@ -152,6 +152,24 @@ impl<'a, 'tcx> euv::Delegate<'tcx> for GatherLoanCtxt<'a, 'tcx> {
                      .node_type(self.bccx.tcx.hir().node_to_hir_id(id));
         gather_moves::gather_decl(self.bccx, &self.move_data, id, ty);
     }
+
+    fn nested_body(&mut self, body_id: hir::BodyId) {
+        debug!("nested_body(body_id={:?})", body_id);
+        // rust-lang/rust#58776: MIR and AST borrow check disagree on where
+        // certain closure errors are reported. As such migrate borrowck has to
+        // operate at the level of items, rather than bodies. Check if the
+        // contained closure had any errors and set `signalled_any_error` if it
+        // has.
+        let bccx = self.bccx;
+        if bccx.tcx.migrate_borrowck() {
+            if let SignalledError::NoErrorsSeen = bccx.signalled_any_error.get() {
+                let closure_def_id = bccx.tcx.hir().body_owner_def_id(body_id);
+                debug!("checking closure: {:?}", closure_def_id);
+
+                bccx.signalled_any_error.set(bccx.tcx.borrowck(closure_def_id).signalled_any_error);
+            }
+        }
+    }
 }
 
 /// Implements the A-* rules in README.md.

src/librustc_lint/lib.rs

@@ -353,6 +353,11 @@ pub fn register_builtins(store: &mut lint::LintStore, sess: Option<&Session>) {
             reference: "issue #57593 <https://github.com/rust-lang/rust/issues/57593>",
             edition: None,
         },
+        FutureIncompatibleInfo {
+            id: LintId::of(NESTED_IMPL_TRAIT),
+            reference: "issue #59014 <https://github.com/rust-lang/rust/issues/59014>",
+            edition: None,
+        },
         ]);
 
     // Register renamed and removed lints.

src/librustc_metadata/cstore_impl.rs

@@ -439,8 +439,8 @@ impl cstore::CStore {
 
         let source_file = sess.parse_sess.source_map().new_source_file(source_name, def.body);
         let local_span = Span::new(source_file.start_pos, source_file.end_pos, NO_EXPANSION);
-        let (body, errors) = source_file_to_stream(&sess.parse_sess, source_file, None);
-        emit_unclosed_delims(&errors, &sess.diagnostic());
+        let (body, mut errors) = source_file_to_stream(&sess.parse_sess, source_file, None);
+        emit_unclosed_delims(&mut errors, &sess.diagnostic());
 
         // Mark the attrs as used
         let attrs = data.get_item_attrs(id.index, sess);

src/librustc_mir/borrow_check/mod.rs

@@ -329,30 +329,12 @@ fn do_mir_borrowck<'a, 'gcx, 'tcx>(
             // When borrowck=migrate, check if AST-borrowck would
             // error on the given code.
 
-            // rust-lang/rust#55492: loop over parents to ensure that
-            // errors that AST-borrowck only detects in some parent of
-            // a closure still allows NLL to signal an error.
-            let mut curr_def_id = def_id;
-            let signalled_any_error = loop {
-                match tcx.borrowck(curr_def_id).signalled_any_error {
-                    SignalledError::NoErrorsSeen => {
-                        // keep traversing (and borrow-checking) parents
-                    }
-                    SignalledError::SawSomeError => {
-                        // stop search here
-                        break SignalledError::SawSomeError;
-                    }
-                }
-
-                if tcx.is_closure(curr_def_id) {
-                    curr_def_id = tcx.parent_def_id(curr_def_id)
-                        .expect("a closure must have a parent_def_id");
-                } else {
-                    break SignalledError::NoErrorsSeen;
-                }
-            };
+            // rust-lang/rust#55492, rust-lang/rust#58776 check the base def id
+            // for errors. AST borrowck is responsible for aggregating
+            // `signalled_any_error` from all of the nested closures here.
+            let base_def_id = tcx.closure_base_def_id(def_id);
 
-            match signalled_any_error {
+            match tcx.borrowck(base_def_id).signalled_any_error {
                 SignalledError::NoErrorsSeen => {
                     // if AST-borrowck signalled no errors, then
                     // downgrade all the buffered MIR-borrowck errors

src/librustc_mir/borrow_check/nll/region_infer/mod.rs

@@ -1357,7 +1357,6 @@ pub trait ClosureRegionRequirementsExt<'gcx, 'tcx> {
     fn apply_requirements(
         &self,
         tcx: TyCtxt<'_, 'gcx, 'tcx>,
-        location: Location,
         closure_def_id: DefId,
         closure_substs: &'tcx ty::subst::Substs<'tcx>,
     ) -> Vec<QueryRegionConstraint<'tcx>>;
@@ -1388,13 +1387,12 @@ impl<'gcx, 'tcx> ClosureRegionRequirementsExt<'gcx, 'tcx> for ClosureRegionRequi
     fn apply_requirements(
         &self,
         tcx: TyCtxt<'_, 'gcx, 'tcx>,
-        location: Location,
         closure_def_id: DefId,
         closure_substs: &'tcx ty::subst::Substs<'tcx>,
     ) -> Vec<QueryRegionConstraint<'tcx>> {
         debug!(
-            "apply_requirements(location={:?}, closure_def_id={:?}, closure_substs={:?})",
-            location, closure_def_id, closure_substs
+            "apply_requirements(closure_def_id={:?}, closure_substs={:?})",
+            closure_def_id, closure_substs
         );
 
         // Extract the values of the free regions in `closure_substs`

src/librustc_mir/borrow_check/nll/region_infer/values.rs

@@ -154,10 +154,10 @@ impl<N: Idx> LivenessValues<N> {
     /// Creates a new set of "region values" that tracks causal information.
     /// Each of the regions in num_region_variables will be initialized with an
     /// empty set of points and no causal information.
-    crate fn new(elements: &Rc<RegionValueElements>) -> Self {
+    crate fn new(elements: Rc<RegionValueElements>) -> Self {
         Self {
-            elements: elements.clone(),
             points: SparseBitMatrix::new(elements.num_points),
+            elements: elements,
         }
     }
 

src/librustc_mir/borrow_check/nll/renumber.rs

@@ -47,6 +47,14 @@ impl<'a, 'gcx, 'tcx> NLLVisitor<'a, 'gcx, 'tcx> {
 }
 
 impl<'a, 'gcx, 'tcx> MutVisitor<'tcx> for NLLVisitor<'a, 'gcx, 'tcx> {
+    fn visit_mir(&mut self, mir: &mut Mir<'tcx>) {
+        for promoted in mir.promoted.iter_mut() {
+            self.visit_mir(promoted);
+        }
+
+        self.super_mir(mir);
+    }
+
     fn visit_ty(&mut self, ty: &mut Ty<'tcx>, ty_context: TyContext) {
         debug!("visit_ty(ty={:?}, ty_context={:?})", ty, ty_context);