Only borrow place for matching under specific conditions
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685a4c6b6b
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74fc64303f
11 changed files with 193 additions and 49 deletions
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@ -100,7 +100,7 @@ fn convert_to_hir_projections_and_truncate_for_capture<'tcx>(
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// single and multiple variants.
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// For single variants, enums are not captured completely.
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// We keep track of VariantIdx so we can use this information
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// if the next ProjectionElem is a Field
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// if the next ProjectionElem is a Field.
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variant = Some(*idx);
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continue;
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}
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@ -420,6 +420,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
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| ExprKind::PlaceTypeAscription { .. }
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| ExprKind::ValueTypeAscription { .. } => {
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debug_assert!(Category::of(&expr.kind) == Some(Category::Place));
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let place = unpack!(block = this.as_place(block, expr));
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let rvalue = Rvalue::Use(this.consume_by_copy_or_move(place));
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this.cfg.push_assign(block, source_info, destination, rvalue);
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@ -436,6 +437,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
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}
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debug_assert!(Category::of(&expr.kind) == Some(Category::Place));
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let place = unpack!(block = this.as_place(block, expr));
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let rvalue = Rvalue::Use(this.consume_by_copy_or_move(place));
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this.cfg.push_assign(block, source_info, destination, rvalue);
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@ -68,7 +68,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
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let match_pairs = mem::take(&mut candidate.match_pairs);
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if let [MatchPair { pattern: Pat { kind: box PatKind::Or { pats }, .. }, place }] =
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&*match_pairs.clone()
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&*match_pairs
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{
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existing_bindings.extend_from_slice(&new_bindings);
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mem::swap(&mut candidate.bindings, &mut existing_bindings);
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@ -155,12 +155,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
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ascription: thir::pattern::Ascription { variance, user_ty, user_ty_span },
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} => {
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// Apply the type ascription to the value at `match_pair.place`, which is the
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// value being matched, taking the variance field into account.
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let place = match_pair.place.clone().into_place(self.tcx, self.typeck_results);
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candidate.ascriptions.push(Ascription {
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span: user_ty_span,
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user_ty,
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source: place,
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source: match_pair.place.clone().into_place(self.tcx, self.typeck_results),
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variance,
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});
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@ -175,12 +173,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
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}
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PatKind::Binding { name, mutability, mode, var, ty, ref subpattern, is_primary: _ } => {
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let place = match_pair.place.clone().into_place(self.tcx, self.typeck_results);
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candidate.bindings.push(Binding {
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name,
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mutability,
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span: match_pair.pattern.span,
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source: place,
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source: match_pair.place.clone().into_place(self.tcx, self.typeck_results),
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var_id: var,
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var_ty: ty,
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binding_mode: mode,
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@ -455,32 +455,18 @@ impl<'thir, 'tcx> Cx<'thir, 'tcx> {
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);
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let fake_reads = match self.typeck_results().closure_fake_reads.get(&def_id) {
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Some(vals) => {
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Some(
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vals.iter()
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.map(|(place, cause)| {
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(
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self.arena.alloc(
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self.convert_captured_hir_place(expr, place.clone()),
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),
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*cause,
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)
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// let var_hir_id = match val.base {
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// HirPlaceBase::Upvar(upvar_id) => {
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// debug!("upvar");
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// upvar_id.var_path.hir_id
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// }
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// _ => {
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// bug!(
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// "Do not know how to get HirId out of Rvalue and StaticItem"
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// );
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// }
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// };
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// self.fake_read_capture_upvar(expr, val.clone(), var_hir_id)
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})
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.collect(),
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)
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}
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Some(vals) => Some(
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vals.iter()
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.map(|(place, cause)| {
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(
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self.arena.alloc(
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self.convert_captured_hir_place(expr, place.clone()),
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),
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*cause,
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)
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})
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.collect(),
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),
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None => None,
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};
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@ -1058,6 +1044,11 @@ impl<'thir, 'tcx> Cx<'thir, 'tcx> {
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let temp_lifetime = self.region_scope_tree.temporary_scope(closure_expr.hir_id.local_id);
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let var_ty = place.base_ty;
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// The result of capture analysis in `rustc_typeck/check/upvar.rs`represents a captured path
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// as it's seen for use within the closure and not at the time of closure creation.
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//
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// That is we see expect to see it start from a captured upvar and not something that is local
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// to the closure's parent.
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let var_hir_id = match place.base {
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HirPlaceBase::Upvar(upvar_id) => upvar_id.var_path.hir_id,
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base => bug!("Expected an upvar, found {:?}", base),
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@ -8,10 +8,10 @@ pub use self::ConsumeMode::*;
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pub use rustc_middle::hir::place::{Place, PlaceBase, PlaceWithHirId, Projection};
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use rustc_hir as hir;
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use rustc_hir::def::{DefKind, Res};
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use rustc_hir::def::Res;
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use rustc_hir::def_id::LocalDefId;
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use rustc_hir::PatKind;
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use rustc_hir::QPath;
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//use rustc_hir::QPath;
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use rustc_index::vec::Idx;
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use rustc_infer::infer::InferCtxt;
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use rustc_middle::hir::place::ProjectionKind;
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@ -54,7 +54,6 @@ pub trait Delegate<'tcx> {
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// `diag_expr_id` is the id used for diagnostics (see `consume` for more details).
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fn mutate(&mut self, assignee_place: &PlaceWithHirId<'tcx>, diag_expr_id: hir::HirId);
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// [FIXME] RFC2229 This should also affect clippy ref: https://github.com/sexxi-goose/rust/pull/27
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fn fake_read(&mut self, place: Place<'tcx>, cause: FakeReadCause);
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}
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@ -235,24 +234,30 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
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hir::ExprKind::Match(ref discr, arms, _) => {
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let discr_place = return_if_err!(self.mc.cat_expr(&discr));
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// Matching should not always be considered a use of the place, hence
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// discr does not necessarily need to be borrowed.
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// We only want to borrow discr if the pattern contain something other
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// than wildcards
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// than wildcards.
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let ExprUseVisitor { ref mc, body_owner: _, delegate: _ } = *self;
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let mut needs_to_be_read = false;
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for arm in arms.iter() {
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return_if_err!(mc.cat_pattern(discr_place.clone(), &arm.pat, |_place, pat| {
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if let PatKind::Binding(_, _, _, opt_sub_pat) = pat.kind {
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if let None = opt_sub_pat {
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needs_to_be_read = true;
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}
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} else if let PatKind::TupleStruct(qpath, _, _) = &pat.kind {
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// If a TupleStruct has a Some PathSegment, we should read the discr_place
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// regardless if it contains a Wild pattern later
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if let QPath::Resolved(_, path) = qpath {
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if let Res::Def(DefKind::Ctor(_, _), _) = path.res {
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match &pat.kind {
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PatKind::Binding(_, _, _, opt_sub_pat) => {
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// If the opt_sub_pat is None, than the binding does not count as
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// a wildcard for the purpose of borrowing discr
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if let None = opt_sub_pat {
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needs_to_be_read = true;
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}
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}
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PatKind::TupleStruct(_, _, _)
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| PatKind::Struct(_, _, _)
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| PatKind::Lit(_) => {
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// If the PatKind is a TupleStruct, Struct, or Lit then we want
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// to borrow discr
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needs_to_be_read = true;
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}
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_ => {}
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}
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}));
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}
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@ -629,6 +634,8 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
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/// - When reporting the Place back to the Delegate, ensure that the UpvarId uses the enclosing
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/// closure as the DefId.
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fn walk_captures(&mut self, closure_expr: &hir::Expr<'_>) {
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debug!("walk_captures({:?})", closure_expr);
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let closure_def_id = self.tcx().hir().local_def_id(closure_expr.hir_id).to_def_id();
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let upvars = self.tcx().upvars_mentioned(self.body_owner);
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@ -645,10 +652,9 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
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if upvars.map_or(body_owner_is_closure, |upvars| {
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!upvars.contains_key(&upvar_id.var_path.hir_id)
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}) {
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// [FIXME] RFC2229 Update this comment
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// The nested closure might be capturing the current (enclosing) closure's local variables.
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// The nested closure might be fake reading the current (enclosing) closure's local variables.
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// We check if the root variable is ever mentioned within the enclosing closure, if not
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// then for the current body (if it's a closure) these aren't captures, we will ignore them.
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// then for the current body (if it's a closure) these do not require fake_read, we will ignore them.
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continue;
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}
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}
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