Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

add notes to report_conflicting_borrow MIR borrowck #44882

Merged
merged 1 commit into from
Oct 4, 2017
Merged

add notes to report_conflicting_borrow MIR borrowck #44882

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
109 changes: 18 additions & 91 deletions src/librustc_borrowck/borrowck/check_loans.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -470,102 +470,29 @@ impl<'a, 'tcx> CheckLoanCtxt<'a, 'tcx> {
old_loan.kill_scope.span(self.tcx(), &self.bccx.region_scope_tree).end_point();

let mut err = match (new_loan.kind, old_loan.kind) {
(ty::MutBorrow, ty::MutBorrow) => {
let mut err = self.bccx.cannot_mutably_borrow_multiply(
new_loan.span, &nl, &new_loan_msg, Origin::Ast);

if new_loan.span == old_loan.span {
// Both borrows are happening in the same place
// Meaning the borrow is occurring in a loop
err.span_label(
new_loan.span,
format!("mutable borrow starts here in previous \
iteration of loop{}", new_loan_msg));
err.span_label(
previous_end_span,
"mutable borrow ends here");
err
} else {
err.span_label(
old_loan.span,
format!("first mutable borrow occurs here{}", old_loan_msg));
err.span_label(
new_loan.span,
format!("second mutable borrow occurs here{}", new_loan_msg));
err.span_label(
previous_end_span,
"first borrow ends here");
err
}
}

(ty::UniqueImmBorrow, ty::UniqueImmBorrow) => {
let mut err = self.bccx.cannot_uniquely_borrow_by_two_closures(
new_loan.span, &nl, Origin::Ast);
err.span_label(
old_loan.span,
"first closure is constructed here");
err.span_label(
new_loan.span,
"second closure is constructed here");
err.span_label(
previous_end_span,
"borrow from first closure ends here");
err
}

(ty::UniqueImmBorrow, _) => {
let mut err = self.bccx.cannot_uniquely_borrow_by_one_closure(
new_loan.span, &nl, &ol_pronoun, &old_loan_msg, Origin::Ast);
err.span_label(
new_loan.span,
format!("closure construction occurs here{}", new_loan_msg));
err.span_label(
old_loan.span,
format!("borrow occurs here{}", old_loan_msg));
err.span_label(
previous_end_span,
"borrow ends here");
err
}

(ty::MutBorrow, ty::MutBorrow) =>
self.bccx.cannot_mutably_borrow_multiply(
new_loan.span, &nl, &new_loan_msg, old_loan.span, &old_loan_msg,
previous_end_span, Origin::Ast),
(ty::UniqueImmBorrow, ty::UniqueImmBorrow) =>
self.bccx.cannot_uniquely_borrow_by_two_closures(
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I'm not sure how "unique" became related to closures. I mean, unique implies closure but not vice-versa (closures can also borrow immutably). But that's pre-existing.

new_loan.span, &nl, old_loan.span, previous_end_span, Origin::Ast),
(ty::UniqueImmBorrow, _) =>
self.bccx.cannot_uniquely_borrow_by_one_closure(
new_loan.span, &nl, &new_loan_msg,
old_loan.span, &ol_pronoun, &old_loan_msg, previous_end_span, Origin::Ast),
(_, ty::UniqueImmBorrow) => {
let new_loan_str = &new_loan.kind.to_user_str();
let mut err = self.bccx.cannot_reborrow_already_uniquely_borrowed(
new_loan.span, &nl, &new_loan_msg, new_loan_str, Origin::Ast);
err.span_label(
new_loan.span,
format!("borrow occurs here{}", new_loan_msg));
err.span_label(
old_loan.span,
format!("closure construction occurs here{}", old_loan_msg));
err.span_label(
previous_end_span,
"borrow from closure ends here");
err
self.bccx.cannot_reborrow_already_uniquely_borrowed(
new_loan.span, &nl, &new_loan_msg, new_loan_str,
old_loan.span, &old_loan_msg, previous_end_span, Origin::Ast)
}

(..) => {
let mut err = self.bccx.cannot_reborrow_already_borrowed(
(..) =>
self.bccx.cannot_reborrow_already_borrowed(
new_loan.span,
&nl, &new_loan_msg, &new_loan.kind.to_user_str(),
&ol_pronoun, &old_loan.kind.to_user_str(), &old_loan_msg, Origin::Ast);
err.span_label(
new_loan.span,
format!("{} borrow occurs here{}",
new_loan.kind.to_user_str(),
new_loan_msg));
err.span_label(
old_loan.span,
format!("{} borrow occurs here{}",
old_loan.kind.to_user_str(),
old_loan_msg));
err.span_label(
previous_end_span,
format!("{} borrow ends here",
old_loan.kind.to_user_str()));
err
}
old_loan.span, &ol_pronoun, &old_loan.kind.to_user_str(), &old_loan_msg,
previous_end_span, Origin::Ast)
};

match new_loan.cause {
Expand Down
61 changes: 34 additions & 27 deletions src/librustc_mir/borrow_check.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -396,28 +396,34 @@ impl<'c, 'b, 'a: 'b+'c, 'gcx, 'tcx: 'a> MirBorrowckCtxt<'c, 'b, 'a, 'gcx, 'tcx>
ReadKind::Copy =>
this.report_use_while_mutably_borrowed(
context, lvalue_span, borrow),
ReadKind::Borrow(bk) =>
ReadKind::Borrow(bk) => {
let end_issued_loan_span =
flow_state.borrows.base_results.operator().region_span(
&borrow.region).end_point();
this.report_conflicting_borrow(
context, lvalue_span,
common_prefix,
(lvalue_span.0, bk), (&borrow.lvalue, borrow.kind)),
context, common_prefix, lvalue_span, bk,
&borrow, end_issued_loan_span)
}
}
Control::Break
}
(Write(kind), _) => {
match kind {
WriteKind::MutableBorrow(bk) =>
WriteKind::MutableBorrow(bk) => {
let end_issued_loan_span =
flow_state.borrows.base_results.operator().region_span(
&borrow.region).end_point();
this.report_conflicting_borrow(
context, lvalue_span,
common_prefix,
(lvalue_span.0, bk), (&borrow.lvalue, borrow.kind)),
context, common_prefix, lvalue_span, bk,
&borrow, end_issued_loan_span)
}
WriteKind::StorageDead |
WriteKind::Mutate =>
this.report_illegal_mutation_of_borrowed(
context, lvalue_span, borrow),
WriteKind::Move =>
this.report_move_out_while_borrowed(
context, lvalue_span, borrow),
context, lvalue_span, &borrow),
}
Control::Break
}
Expand Down Expand Up @@ -966,48 +972,49 @@ impl<'c, 'b, 'a: 'b+'c, 'gcx, 'tcx: 'a> MirBorrowckCtxt<'c, 'b, 'a, 'gcx, 'tcx>

fn report_conflicting_borrow(&mut self,
_context: Context,
(lvalue, span): (&Lvalue, Span),
common_prefix: &Lvalue,
loan1: (&Lvalue, BorrowKind),
loan2: (&Lvalue, BorrowKind)) {
(lvalue, span): (&Lvalue, Span),
gen_borrow_kind: BorrowKind,
issued_borrow: &BorrowData,
end_issued_loan_span: Span) {
use self::prefixes::IsPrefixOf;

let (loan1_lvalue, loan1_kind) = loan1;
let (loan2_lvalue, loan2_kind) = loan2;
assert!(common_prefix.is_prefix_of(lvalue));
assert!(common_prefix.is_prefix_of(&issued_borrow.lvalue));

assert!(common_prefix.is_prefix_of(loan1_lvalue));
assert!(common_prefix.is_prefix_of(loan2_lvalue));
let issued_span = self.retrieve_borrow_span(issued_borrow);

// FIXME: supply non-"" `opt_via` when appropriate
let mut err = match (loan1_kind, "immutable", "mutable",
loan2_kind, "immutable", "mutable") {
let mut err = match (gen_borrow_kind, "immutable", "mutable",
issued_borrow.kind, "immutable", "mutable") {
(BorrowKind::Shared, lft, _, BorrowKind::Mut, _, rgt) |
(BorrowKind::Mut, _, lft, BorrowKind::Shared, rgt, _) =>
self.tcx.cannot_reborrow_already_borrowed(
span, &self.describe_lvalue(lvalue),
"", lft, "it", rgt, "", Origin::Mir),
span, &self.describe_lvalue(lvalue), "", lft, issued_span,
"it", rgt, "", end_issued_loan_span, Origin::Mir),

(BorrowKind::Mut, _, _, BorrowKind::Mut, _, _) =>
self.tcx.cannot_mutably_borrow_multiply(
span, &self.describe_lvalue(lvalue), "", Origin::Mir),
span, &self.describe_lvalue(lvalue), "", issued_span,
"", end_issued_loan_span, Origin::Mir),

(BorrowKind::Unique, _, _, BorrowKind::Unique, _, _) =>
self.tcx.cannot_uniquely_borrow_by_two_closures(
span, &self.describe_lvalue(lvalue), Origin::Mir),
span, &self.describe_lvalue(lvalue), issued_span,
end_issued_loan_span, Origin::Mir),

(BorrowKind::Unique, _, _, _, _, _) =>
self.tcx.cannot_uniquely_borrow_by_one_closure(
span, &self.describe_lvalue(lvalue), "it", "", Origin::Mir),
span, &self.describe_lvalue(lvalue), "",
issued_span, "it", "", end_issued_loan_span, Origin::Mir),

(_, _, _, BorrowKind::Unique, _, _) =>
self.tcx.cannot_reborrow_already_uniquely_borrowed(
span, &self.describe_lvalue(lvalue), "it", "", Origin::Mir),
span, &self.describe_lvalue(lvalue), "it", "",
issued_span, "", end_issued_loan_span, Origin::Mir),

(BorrowKind::Shared, _, _, BorrowKind::Shared, _, _) =>
unreachable!(),

// FIXME: add span labels for first and second mutable borrows, as well as
// end point for first.
};
err.emit();
}
Expand Down
27 changes: 25 additions & 2 deletions src/librustc_mir/dataflow/impls/borrows.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@
use rustc::mir::{self, Location, Mir};
use rustc::mir::visit::Visitor;
use rustc::ty::{Region, TyCtxt};
use rustc::ty::RegionKind;
use rustc::ty::RegionKind::ReScope;
use rustc::util::nodemap::{FxHashMap, FxHashSet};

Expand All @@ -21,6 +22,8 @@ use rustc_data_structures::indexed_vec::{IndexVec};
use dataflow::{BitDenotation, BlockSets, DataflowOperator};
pub use dataflow::indexes::BorrowIndex;

use syntax_pos::Span;

use std::fmt;

// `Borrows` maps each dataflow bit to an `Rvalue::Ref`, which can be
Expand All @@ -32,6 +35,7 @@ pub struct Borrows<'a, 'tcx: 'a> {
borrows: IndexVec<BorrowIndex, BorrowData<'tcx>>,
location_map: FxHashMap<Location, BorrowIndex>,
region_map: FxHashMap<Region<'tcx>, FxHashSet<BorrowIndex>>,
region_span_map: FxHashMap<RegionKind, Span>,
}

// temporarily allow some dead fields: `kind` and `region` will be
Expand Down Expand Up @@ -63,18 +67,21 @@ impl<'a, 'tcx> Borrows<'a, 'tcx> {
pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>, mir: &'a Mir<'tcx>) -> Self {
let mut visitor = GatherBorrows { idx_vec: IndexVec::new(),
location_map: FxHashMap(),
region_map: FxHashMap(), };
region_map: FxHashMap(),
region_span_map: FxHashMap()};
visitor.visit_mir(mir);
return Borrows { tcx: tcx,
mir: mir,
borrows: visitor.idx_vec,
location_map: visitor.location_map,
region_map: visitor.region_map, };
region_map: visitor.region_map,
region_span_map: visitor.region_span_map};

struct GatherBorrows<'tcx> {
idx_vec: IndexVec<BorrowIndex, BorrowData<'tcx>>,
location_map: FxHashMap<Location, BorrowIndex>,
region_map: FxHashMap<Region<'tcx>, FxHashSet<BorrowIndex>>,
region_span_map: FxHashMap<RegionKind, Span>,
}
impl<'tcx> Visitor<'tcx> for GatherBorrows<'tcx> {
fn visit_rvalue(&mut self,
Expand All @@ -90,6 +97,16 @@ impl<'a, 'tcx> Borrows<'a, 'tcx> {
borrows.insert(idx);
}
}

fn visit_statement(&mut self,
block: mir::BasicBlock,
statement: &mir::Statement<'tcx>,
location: Location) {
if let mir::StatementKind::EndRegion(region_scope) = statement.kind {
self.region_span_map.insert(ReScope(region_scope), statement.source_info.span);
}
self.super_statement(block, statement, location);
}
}
}

Expand All @@ -98,6 +115,12 @@ impl<'a, 'tcx> Borrows<'a, 'tcx> {
pub fn location(&self, idx: BorrowIndex) -> &Location {
&self.borrows[idx].location
}

pub fn region_span(&self, region: &Region) -> Span {
let opt_span = self.region_span_map.get(region);
assert!(opt_span.is_some(), "end region not found for {:?}", region);
*opt_span.unwrap()
}
}

impl<'a, 'tcx> BitDenotation for Borrows<'a, 'tcx> {
Expand Down
Loading