Rollup of 7 pull requests

compiler/rustc_middle/src/mir/mod.rs

@@ -1482,7 +1482,7 @@ pub enum StatementKind<'tcx> {
     ///
     /// Note that this also is emitted for regular `let` bindings to ensure that locals that are
     /// never accessed still get some sanity checks for, e.g., `let x: ! = ..;`
-    FakeRead(FakeReadCause, Box<Place<'tcx>>),
+    FakeRead(Box<(FakeReadCause, Place<'tcx>)>),
 
     /// Write the discriminant for a variant to the enum Place.
     SetDiscriminant { place: Box<Place<'tcx>>, variant_index: VariantIdx },
@@ -1575,7 +1575,12 @@ pub enum FakeReadCause {
 
     /// `let x: !; match x {}` doesn't generate any read of x so we need to
     /// generate a read of x to check that it is initialized and safe.
-    ForMatchedPlace,
+    ///
+    /// If a closure pattern matches a Place starting with an Upvar, then we introduce a
+    /// FakeRead for that Place outside the closure, in such a case this option would be
+    /// Some(closure_def_id).
+    /// Otherwise, the value of the optional DefId will be None.
+    ForMatchedPlace(Option<DefId>),
 
     /// A fake read of the RefWithinGuard version of a bind-by-value variable
     /// in a match guard to ensure that it's value hasn't change by the time
@@ -1594,7 +1599,12 @@ pub enum FakeReadCause {
     /// but in some cases it can affect the borrow checker, as in #53695.
     /// Therefore, we insert a "fake read" here to ensure that we get
     /// appropriate errors.
-    ForLet,
+    ///
+    /// If a closure pattern matches a Place starting with an Upvar, then we introduce a
+    /// FakeRead for that Place outside the closure, in such a case this option would be
+    /// Some(closure_def_id).
+    /// Otherwise, the value of the optional DefId will be None.
+    ForLet(Option<DefId>),
 
     /// If we have an index expression like
     ///
@@ -1618,7 +1628,9 @@ impl Debug for Statement<'_> {
         use self::StatementKind::*;
         match self.kind {
             Assign(box (ref place, ref rv)) => write!(fmt, "{:?} = {:?}", place, rv),
-            FakeRead(ref cause, ref place) => write!(fmt, "FakeRead({:?}, {:?})", cause, place),
+            FakeRead(box (ref cause, ref place)) => {
+                write!(fmt, "FakeRead({:?}, {:?})", cause, place)
+            }
             Retag(ref kind, ref place) => write!(
                 fmt,
                 "Retag({}{:?})",

compiler/rustc_middle/src/mir/visit.rs

@@ -380,7 +380,7 @@ macro_rules! make_mir_visitor {
                     ) => {
                         self.visit_assign(place, rvalue, location);
                     }
-                    StatementKind::FakeRead(_, place) => {
+                    StatementKind::FakeRead(box (_, place)) => {
                         self.visit_place(
                             place,
                             PlaceContext::NonMutatingUse(NonMutatingUseContext::Inspect),

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

@@ -1728,7 +1728,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         impl<'tcx> Visitor<'tcx> for FakeReadCauseFinder<'tcx> {
             fn visit_statement(&mut self, statement: &Statement<'tcx>, _: Location) {
                 match statement {
-                    Statement { kind: StatementKind::FakeRead(cause, box place), .. }
+                    Statement { kind: StatementKind::FakeRead(box (cause, place)), .. }
                         if *place == self.place =>
                     {
                         self.cause = Some(*cause);

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

@@ -515,7 +515,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 let block = &self.body.basic_blocks()[location.block];
 
                 let kind = if let Some(&Statement {
-                    kind: StatementKind::FakeRead(FakeReadCause::ForLet, _),
+                    kind: StatementKind::FakeRead(box (FakeReadCause::ForLet(_), _)),
                     ..
                 }) = block.statements.get(location.statement_index)
                 {

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

@@ -7,8 +7,8 @@ use rustc_hir::def_id::DefId;
 use rustc_hir::lang_items::LangItemGroup;
 use rustc_hir::GeneratorKind;
 use rustc_middle::mir::{
-    AggregateKind, Constant, Field, Local, LocalInfo, LocalKind, Location, Operand, Place,
-    PlaceRef, ProjectionElem, Rvalue, Statement, StatementKind, Terminator, TerminatorKind,
+    AggregateKind, Constant, FakeReadCause, Field, Local, LocalInfo, LocalKind, Location, Operand,
+    Place, PlaceRef, ProjectionElem, Rvalue, Statement, StatementKind, Terminator, TerminatorKind,
 };
 use rustc_middle::ty::print::Print;
 use rustc_middle::ty::{self, DefIdTree, Instance, Ty, TyCtxt};
@@ -795,6 +795,24 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             }
         }
 
+        // StatementKind::FakeRead only contains a def_id if they are introduced as a result
+        // of pattern matching within a closure.
+        if let StatementKind::FakeRead(box (cause, ref place)) = stmt.kind {
+            match cause {
+                FakeReadCause::ForMatchedPlace(Some(closure_def_id))
+                | FakeReadCause::ForLet(Some(closure_def_id)) => {
+                    debug!("move_spans: def_id={:?} place={:?}", closure_def_id, place);
+                    let places = &[Operand::Move(*place)];
+                    if let Some((args_span, generator_kind, var_span)) =
+                        self.closure_span(closure_def_id, moved_place, places)
+                    {
+                        return ClosureUse { generator_kind, args_span, var_span };
+                    }
+                }
+                _ => {}
+            }
+        }
+
         let normal_ret =
             if moved_place.projection.iter().any(|p| matches!(p, ProjectionElem::Downcast(..))) {
                 PatUse(stmt.source_info.span)

compiler/rustc_mir/src/borrow_check/invalidation.rs

@@ -63,7 +63,7 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
 
                 self.mutate_place(location, *lhs, Shallow(None), JustWrite);
             }
-            StatementKind::FakeRead(_, _) => {
+            StatementKind::FakeRead(box (_, _)) => {
                 // Only relevant for initialized/liveness/safety checks.
             }
             StatementKind::SetDiscriminant { place, variant_index: _ } => {

compiler/rustc_mir/src/borrow_check/mod.rs

@@ -574,7 +574,7 @@ impl<'cx, 'tcx> dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtxt<'cx, 'tc
 
                 self.mutate_place(location, (*lhs, span), Shallow(None), JustWrite, flow_state);
             }
-            StatementKind::FakeRead(_, box ref place) => {
+            StatementKind::FakeRead(box (_, ref place)) => {
                 // Read for match doesn't access any memory and is used to
                 // assert that a place is safe and live. So we don't have to
                 // do any checks here.

compiler/rustc_mir/src/dataflow/move_paths/builder.rs

@@ -293,8 +293,8 @@ impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {
                 }
                 self.gather_rvalue(rval);
             }
-            StatementKind::FakeRead(_, place) => {
-                self.create_move_path(**place);
+            StatementKind::FakeRead(box (_, place)) => {
+                self.create_move_path(*place);
             }
             StatementKind::LlvmInlineAsm(ref asm) => {
                 for (output, kind) in iter::zip(&*asm.outputs, &asm.asm.outputs) {

compiler/rustc_mir/src/transform/coverage/spans.rs

@@ -683,10 +683,10 @@ pub(super) fn filtered_statement_span(
         // and `_1` is the `Place` for `somenum`.
         //
         // If and when the Issue is resolved, remove this special case match pattern:
-        StatementKind::FakeRead(cause, _) if cause == FakeReadCause::ForGuardBinding => None,
+        StatementKind::FakeRead(box (cause, _)) if cause == FakeReadCause::ForGuardBinding => None,
 
         // Retain spans from all other statements
-        StatementKind::FakeRead(_, _) // Not including `ForGuardBinding`
+        StatementKind::FakeRead(box (_, _)) // Not including `ForGuardBinding`
         | StatementKind::CopyNonOverlapping(..)
         | StatementKind::Assign(_)
         | StatementKind::SetDiscriminant { .. }

compiler/rustc_mir_build/src/build/cfg.rs

@@ -80,7 +80,7 @@ impl<'tcx> CFG<'tcx> {
         cause: FakeReadCause,
         place: Place<'tcx>,
     ) {
-        let kind = StatementKind::FakeRead(cause, box place);
+        let kind = StatementKind::FakeRead(box (cause, place));
         let stmt = Statement { source_info, kind };
         self.push(block, stmt);
     }

compiler/rustc_mir_build/src/build/expr/as_rvalue.rs

@@ -179,24 +179,20 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 //     match x { _ => () } // fake read of `x`
                 // };
                 // ```
-                // FIXME(RFC2229): Remove feature gate once diagnostics are improved
-                if this.tcx.features().capture_disjoint_fields {
-                    for (thir_place, cause, hir_id) in fake_reads.into_iter() {
-                        let place_builder =
-                            unpack!(block = this.as_place_builder(block, thir_place));
-
-                        if let Ok(place_builder_resolved) =
-                            place_builder.try_upvars_resolved(this.tcx, this.typeck_results)
-                        {
-                            let mir_place =
-                                place_builder_resolved.into_place(this.tcx, this.typeck_results);
-                            this.cfg.push_fake_read(
-                                block,
-                                this.source_info(this.tcx.hir().span(*hir_id)),
-                                *cause,
-                                mir_place,
-                            );
-                        }
+                for (thir_place, cause, hir_id) in fake_reads.into_iter() {
+                    let place_builder = unpack!(block = this.as_place_builder(block, thir_place));
+
+                    if let Ok(place_builder_resolved) =
+                        place_builder.try_upvars_resolved(this.tcx, this.typeck_results)
+                    {
+                        let mir_place =
+                            place_builder_resolved.into_place(this.tcx, this.typeck_results);
+                        this.cfg.push_fake_read(
+                            block,
+                            this.source_info(this.tcx.hir().span(*hir_id)),
+                            *cause,
+                            mir_place,
+                        );
                     }
                 }
 

compiler/rustc_mir_build/src/build/matches/mod.rs

@@ -139,7 +139,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         // uninhabited value. If we get never patterns, those will check that
         // the place is initialized, and so this read would only be used to
         // check safety.
-        let cause_matched_place = FakeReadCause::ForMatchedPlace;
+        let cause_matched_place = FakeReadCause::ForMatchedPlace(None);
         let source_info = self.source_info(scrutinee_span);
 
         if let Ok(scrutinee_builder) =
@@ -400,7 +400,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
                 // Inject a fake read, see comments on `FakeReadCause::ForLet`.
                 let source_info = self.source_info(irrefutable_pat.span);
-                self.cfg.push_fake_read(block, source_info, FakeReadCause::ForLet, place);
+                self.cfg.push_fake_read(block, source_info, FakeReadCause::ForLet(None), place);
 
                 self.schedule_drop_for_binding(var, irrefutable_pat.span, OutsideGuard);
                 block.unit()
@@ -435,7 +435,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
                 // Inject a fake read, see comments on `FakeReadCause::ForLet`.
                 let pattern_source_info = self.source_info(irrefutable_pat.span);
-                let cause_let = FakeReadCause::ForLet;
+                let cause_let = FakeReadCause::ForLet(None);
                 self.cfg.push_fake_read(block, pattern_source_info, cause_let, place);
 
                 let ty_source_info = self.source_info(user_ty_span);

compiler/rustc_session/src/config.rs

@@ -953,7 +953,7 @@ pub fn build_target_config(opts: &Options, target_override: Option<Target>) -> T
             opts.error_format,
             &format!(
                 "Error loading target specification: {}. \
-            Use `--print target-list` for a list of built-in targets",
+                 Run `rustc --print target-list` for a list of built-in targets",
                 e
             ),
         )

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

@@ -28,6 +28,7 @@ use std::fmt;
 
 use super::InferCtxtPrivExt;
 use crate::traits::query::evaluate_obligation::InferCtxtExt as _;
+use rustc_middle::ty::print::with_no_trimmed_paths;
 
 #[derive(Debug)]
 pub enum GeneratorInteriorOrUpvar {
@@ -440,7 +441,8 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                 {
                     // Missing generic type parameter bound.
                     let param_name = self_ty.to_string();
-                    let constraint = trait_ref.print_only_trait_path().to_string();
+                    let constraint =
+                        with_no_trimmed_paths(|| trait_ref.print_only_trait_path().to_string());
                     if suggest_constraining_type_param(
                         self.tcx,
                         generics,
@@ -2067,7 +2069,14 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
 
                 // Don't print the tuple of capture types
                 if !is_upvar_tys_infer_tuple {
-                    err.note(&format!("required because it appears within the type `{}`", ty));
+                    let msg = format!("required because it appears within the type `{}`", ty);
+                    match ty.kind() {
+                        ty::Adt(def, _) => match self.tcx.opt_item_name(def.did) {
+                            Some(ident) => err.span_note(ident.span, &msg),
+                            None => err.note(&msg),
+                        },
+                        _ => err.note(&msg),
+                    };
                 }
 
                 obligated_types.push(ty);
@@ -2089,11 +2098,36 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
             ObligationCauseCode::ImplDerivedObligation(ref data) => {
                 let mut parent_trait_ref = self.resolve_vars_if_possible(data.parent_trait_ref);
                 let parent_def_id = parent_trait_ref.def_id();
-                err.note(&format!(
+                let msg = format!(
                     "required because of the requirements on the impl of `{}` for `{}`",
                     parent_trait_ref.print_only_trait_path(),
                     parent_trait_ref.skip_binder().self_ty()
-                ));
+                );
+                let mut candidates = vec![];
+                self.tcx.for_each_relevant_impl(
+                    parent_def_id,
+                    parent_trait_ref.self_ty().skip_binder(),
+                    |impl_def_id| {
+                        candidates.push(impl_def_id);
+                    },
+                );
+                match &candidates[..] {
+                    [def_id] => match self.tcx.hir().get_if_local(*def_id) {
+                        Some(Node::Item(hir::Item {
+                            kind: hir::ItemKind::Impl(hir::Impl { of_trait, self_ty, .. }),
+                            ..
+                        })) => {
+                            let mut spans = Vec::with_capacity(2);
+                            if let Some(trait_ref) = of_trait {
+                                spans.push(trait_ref.path.span);
+                            }
+                            spans.push(self_ty.span);
+                            err.span_note(spans, &msg)
+                        }
+                        _ => err.note(&msg),
+                    },
+                    _ => err.note(&msg),
+                };
 
                 let mut parent_predicate = parent_trait_ref.without_const().to_predicate(tcx);
                 let mut data = data;