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Auto merge of #51638 - spastorino:diagnostic-suggest-drop-in-reverse,…
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… r=nikomatsakis

Diagnostic suggest drop in reverse

Closes #51195
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@bors
bors committed Jun 20, 2018
2 parents cca43a7 + d3defca commit 7d313ea
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Showing 22 changed files with 784 additions and 454 deletions.
961 changes: 611 additions & 350 deletions src/librustc/mir/mod.rs
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98 changes: 50 additions & 48 deletions src/librustc_mir/borrow_check/error_reporting.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,20 +8,21 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use syntax_pos::Span;
use borrow_check::WriteKind;
use rustc::middle::region::ScopeTree;
use rustc::mir::{BorrowKind, Field, Local, LocalKind, Location, Operand};
use rustc::mir::{Place, ProjectionElem, Rvalue, Statement, StatementKind};
use rustc::ty::{self, RegionKind};
use rustc_data_structures::indexed_vec::Idx;
use rustc_data_structures::sync::Lrc;
use syntax_pos::Span;

use super::borrow_set::BorrowData;
use super::{Context, MirBorrowckCtxt};
use super::{InitializationRequiringAction, PrefixSet};
use super::borrow_set::BorrowData;

use dataflow::{FlowAtLocation, MovingOutStatements};
use dataflow::move_paths::MovePathIndex;
use dataflow::{FlowAtLocation, MovingOutStatements};
use util::borrowck_errors::{BorrowckErrors, Origin};

impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
Expand All @@ -39,22 +40,17 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
.collect::<Vec<_>>();

if mois.is_empty() {
let root_place = self.prefixes(&place, PrefixSet::All)
.last()
.unwrap();
let root_place = self.prefixes(&place, PrefixSet::All).last().unwrap();

if self.moved_error_reported
.contains(&root_place.clone())
{
if self.moved_error_reported.contains(&root_place.clone()) {
debug!(
"report_use_of_moved_or_uninitialized place: error about {:?} suppressed",
root_place
);
return;
}

self.moved_error_reported
.insert(root_place.clone());
self.moved_error_reported.insert(root_place.clone());

let item_msg = match self.describe_place(place) {
Some(name) => format!("`{}`", name),
Expand Down Expand Up @@ -162,7 +158,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
format!("borrow of {} occurs here", borrow_msg),
);
err.span_label(span, format!("move out of {} occurs here", value_msg));
self.explain_why_borrow_contains_point(context, borrow, &mut err);
self.explain_why_borrow_contains_point(context, borrow, None, &mut err);
err.emit();
}

Expand All @@ -177,12 +173,13 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
span,
&self.describe_place(place).unwrap_or("_".to_owned()),
self.retrieve_borrow_span(borrow),
&self.describe_place(&borrow.borrowed_place)
&self
.describe_place(&borrow.borrowed_place)
.unwrap_or("_".to_owned()),
Origin::Mir,
);

self.explain_why_borrow_contains_point(context, borrow, &mut err);
self.explain_why_borrow_contains_point(context, borrow, None, &mut err);

err.emit();
}
Expand Down Expand Up @@ -286,8 +283,8 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
"mutable",
) {
(BorrowKind::Shared, lft, _, BorrowKind::Mut { .. }, _, rgt)
| (BorrowKind::Mut { .. }, _, lft, BorrowKind::Shared, rgt, _) => {
tcx.cannot_reborrow_already_borrowed(
| (BorrowKind::Mut { .. }, _, lft, BorrowKind::Shared, rgt, _) => tcx
.cannot_reborrow_already_borrowed(
span,
&desc_place,
"",
Expand All @@ -298,30 +295,27 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
"",
None,
Origin::Mir,
)
}
),

(BorrowKind::Mut { .. }, _, _, BorrowKind::Mut { .. }, _, _) => {
tcx.cannot_mutably_borrow_multiply(
(BorrowKind::Mut { .. }, _, _, BorrowKind::Mut { .. }, _, _) => tcx
.cannot_mutably_borrow_multiply(
span,
&desc_place,
"",
issued_span,
"",
None,
Origin::Mir,
)
}
),

(BorrowKind::Unique, _, _, BorrowKind::Unique, _, _) => {
tcx.cannot_uniquely_borrow_by_two_closures(
(BorrowKind::Unique, _, _, BorrowKind::Unique, _, _) => tcx
.cannot_uniquely_borrow_by_two_closures(
span,
&desc_place,
issued_span,
None,
Origin::Mir,
)
}
),

(BorrowKind::Unique, _, _, _, _, _) => tcx.cannot_uniquely_borrow_by_one_closure(
span,
Expand All @@ -334,8 +328,8 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
Origin::Mir,
),

(BorrowKind::Shared, lft, _, BorrowKind::Unique, _, _) => {
tcx.cannot_reborrow_already_uniquely_borrowed(
(BorrowKind::Shared, lft, _, BorrowKind::Unique, _, _) => tcx
.cannot_reborrow_already_uniquely_borrowed(
span,
&desc_place,
"",
Expand All @@ -344,11 +338,10 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
"",
None,
Origin::Mir,
)
}
),

(BorrowKind::Mut { .. }, _, lft, BorrowKind::Unique, _, _) => {
tcx.cannot_reborrow_already_uniquely_borrowed(
(BorrowKind::Mut { .. }, _, lft, BorrowKind::Unique, _, _) => tcx
.cannot_reborrow_already_uniquely_borrowed(
span,
&desc_place,
"",
Expand All @@ -357,8 +350,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
"",
None,
Origin::Mir,
)
}
),

(BorrowKind::Shared, _, _, BorrowKind::Shared, _, _) => unreachable!(),
};
Expand All @@ -380,7 +372,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
);
}

self.explain_why_borrow_contains_point(context, issued_borrow, &mut err);
self.explain_why_borrow_contains_point(context, issued_borrow, None, &mut err);

err.emit();
}
Expand All @@ -389,10 +381,13 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
&mut self,
context: Context,
borrow: &BorrowData<'tcx>,
drop_span: Span,
place_span: (&Place<'tcx>, Span),
kind: Option<WriteKind>,
) {
let drop_span = place_span.1;
let scope_tree = self.tcx.region_scope_tree(self.mir_def_id);
let root_place = self.prefixes(&borrow.borrowed_place, PrefixSet::All)
let root_place = self
.prefixes(&borrow.borrowed_place, PrefixSet::All)
.last()
.unwrap();

Expand All @@ -402,7 +397,8 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
_ => drop_span,
};

if self.access_place_error_reported
if self
.access_place_error_reported
.contains(&(root_place.clone(), borrow_span))
{
debug!(
Expand Down Expand Up @@ -450,6 +446,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
drop_span,
borrow_span,
proper_span,
kind.map(|k| (k, place_span.0)),
);
}
(RegionKind::ReEarlyBound(_), None)
Expand All @@ -471,8 +468,11 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
| (RegionKind::ReClosureBound(_), _)
| (RegionKind::ReCanonical(_), _)
| (RegionKind::ReErased, _) => {
span_bug!(drop_span, "region {:?} does not make sense in this context",
borrow.region);
span_bug!(
drop_span,
"region {:?} does not make sense in this context",
borrow.region
);
}
}
}
Expand All @@ -495,7 +495,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
drop_span,
format!("`{}` dropped here while still borrowed", name),
);
self.explain_why_borrow_contains_point(context, borrow, &mut err);
self.explain_why_borrow_contains_point(context, borrow, None, &mut err);
err.emit();
}

Expand All @@ -517,7 +517,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
"temporary value dropped here while still borrowed",
);
err.note("consider using a `let` binding to increase its lifetime");
self.explain_why_borrow_contains_point(context, borrow, &mut err);
self.explain_why_borrow_contains_point(context, borrow, None, &mut err);
err.emit();
}

Expand All @@ -530,6 +530,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
drop_span: Span,
borrow_span: Span,
_proper_span: Span,
kind_place: Option<(WriteKind, &Place<'tcx>)>,
) {
debug!(
"report_unscoped_local_value_does_not_live_long_enough(\
Expand All @@ -544,7 +545,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
err.span_label(borrow_span, "borrowed value does not live long enough");
err.span_label(drop_span, "borrowed value only lives until here");

self.explain_why_borrow_contains_point(context, borrow, &mut err);
self.explain_why_borrow_contains_point(context, borrow, kind_place, &mut err);
err.emit();
}

Expand All @@ -570,7 +571,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
err.span_label(proper_span, "temporary value does not live long enough");
err.span_label(drop_span, "temporary value only lives until here");

self.explain_why_borrow_contains_point(context, borrow, &mut err);
self.explain_why_borrow_contains_point(context, borrow, None, &mut err);
err.emit();
}

Expand All @@ -588,7 +589,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
Origin::Mir,
);

self.explain_why_borrow_contains_point(context, loan, &mut err);
self.explain_why_borrow_contains_point(context, loan, None, &mut err);

err.emit();
}
Expand Down Expand Up @@ -759,9 +760,10 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
Place::Static(ref static_) => self.describe_field_from_ty(&static_.ty, field),
Place::Projection(ref proj) => match proj.elem {
ProjectionElem::Deref => self.describe_field(&proj.base, field),
ProjectionElem::Downcast(def, variant_index) => {
format!("{}", def.variants[variant_index].fields[field.index()].ident)
}
ProjectionElem::Downcast(def, variant_index) => format!(
"{}",
def.variants[variant_index].fields[field.index()].ident
),
ProjectionElem::Field(_, field_type) => {
self.describe_field_from_ty(&field_type, field)
}
Expand Down
6 changes: 4 additions & 2 deletions src/librustc_mir/borrow_check/mod.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1050,7 +1050,8 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
this.report_borrowed_value_does_not_live_long_enough(
context,
borrow,
place_span.1,
place_span,
Some(kind),
);
}
WriteKind::Mutate => {
Expand Down Expand Up @@ -1328,7 +1329,8 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
self.report_borrowed_value_does_not_live_long_enough(
context,
borrow,
span,
(place, span),
None,
)
}
}
Expand Down
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