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Deduplicated borrow checking errors.

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David Wood 2017-11-14 19:47:31 +00:00
parent d0f8e2913a
commit 7db49b9612
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GPG key ID: 01760B4F9F53F154
1 changed files with 29 additions and 10 deletions
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39
src/librustc_mir/borrow_check.rs
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@ -20,6 +20,7 @@ use rustc::mir::{Mir, Mutability, Operand, Projection, ProjectionElem, Rvalue};
use rustc::mir::{Statement, StatementKind, Terminator, TerminatorKind};
use transform::nll;
use rustc_data_structures::fx::FxHashSet;
use rustc_data_structures::indexed_set::{self, IdxSetBuf};
use rustc_data_structures::indexed_vec::{Idx};
@ -136,6 +137,7 @@ fn do_mir_borrowck<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
node_id: id,
move_data: &mdpe.move_data,
param_env: param_env,
storage_drop_or_dead_error_reported: FxHashSet(),
};
let mut state = InProgress::new(flow_borrows,
@ -153,6 +155,10 @@ pub struct MirBorrowckCtxt<'cx, 'gcx: 'tcx, 'tcx: 'cx> {
node_id: ast::NodeId,
move_data: &'cx MoveData<'tcx>,
param_env: ParamEnv<'gcx>,
/// This field keeps track of when storage drop or dead errors are reported
/// in order to stop duplicate error reporting and identify the conditions required
/// for a "temporary value dropped here while still borrowed" error. See #45360.
storage_drop_or_dead_error_reported: FxHashSet<Local>,
}
// (forced to be `pub` due to its use as an associated type below.)
@ -281,10 +287,12 @@ impl<'cx, 'gcx, 'tcx> DataflowResultsConsumer<'cx, 'tcx> for MirBorrowckCtxt<'cx
}
StatementKind::StorageDead(local) => {
self.access_lvalue(ContextKind::StorageDead.new(location),
(&Lvalue::Local(local), span),
(Shallow(None), Write(WriteKind::StorageDead)),
flow_state);
if self.storage_drop_or_dead_error_reported.insert(local) {
self.access_lvalue(ContextKind::StorageDead.new(location),
(&Lvalue::Local(local), span),
(Shallow(None), Write(WriteKind::StorageDead)),
flow_state);
}
}
}
}
@ -604,12 +612,23 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
let erased_ty = gcx.lift(&self.tcx.erase_regions(&ty)).unwrap();
let moves_by_default = erased_ty.moves_by_default(gcx, self.param_env, DUMMY_SP);
if moves_by_default {
// move of lvalue: check if this is move of already borrowed path
self.access_lvalue(context, lvalue_span, (Deep, Write(WriteKind::Move)), flow_state);
} else {
// copy of lvalue: check if this is "copy of frozen path" (FIXME: see check_loans.rs)
self.access_lvalue(context, lvalue_span, (Deep, Read(ReadKind::Copy)), flow_state);
// Check if error has already been reported to stop duplicate reporting.
let has_storage_drop_or_dead_error_reported = match *lvalue {
Lvalue::Local(local) => self.storage_drop_or_dead_error_reported.insert(local),
_ => false,
};
if !has_storage_drop_or_dead_error_reported {
if moves_by_default {
// move of lvalue: check if this is move of already borrowed path
self.access_lvalue(context, lvalue_span, (Deep, Write(WriteKind::Move)),
flow_state);
} else {
// copy of lvalue: check if this is "copy of frozen path"
// (FIXME: see check_loans.rs)
self.access_lvalue(context, lvalue_span, (Deep, Read(ReadKind::Copy)),
flow_state);
}
}
// Finally, check if path was already moved.