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Add helper method to determine if local had ever been initialized at current point in flow.

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This commit is contained in:
Felix S. Klock II 2018-10-16 15:45:24 +02:00
parent bc61541423
commit d0416cc093
1 changed files with 25 additions and 19 deletions
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44
src/librustc_mir/borrow_check/mod.rs
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@ -36,9 +36,8 @@ use std::collections::BTreeMap;
use syntax_pos::Span;
use dataflow::indexes::BorrowIndex;
use dataflow::move_paths::{HasMoveData, LookupResult, MoveData, MoveError, MovePathIndex};
use dataflow::move_paths::indexes::MoveOutIndex;
use dataflow::indexes::{BorrowIndex, InitIndex, MoveOutIndex, MovePathIndex};
use dataflow::move_paths::{HasMoveData, LookupResult, MoveData, MoveError};
use dataflow::Borrows;
use dataflow::DataflowResultsConsumer;
use dataflow::FlowAtLocation;
@ -1442,10 +1441,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
debug!("check_if_reassignment_to_immutable_state({:?})", local);
// Check if any of the initializiations of `local` have happened yet:
let mpi = self.move_data.rev_lookup.find_local(local);
let init_indices = &self.move_data.init_path_map[mpi];
let first_init_index = init_indices.iter().find(|&ii| flow_state.ever_inits.contains(*ii));
if let Some(&init_index) = first_init_index {
if let Some(init_index) = self.is_local_ever_initialized(local, flow_state) {
// And, if so, report an error.
let init = &self.move_data.inits[init_index];
let span = init.span(&self.mir);
@ -1889,6 +1885,21 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
return true;
}
fn is_local_ever_initialized(&self,
local: Local,
flow_state: &Flows<'cx, 'gcx, 'tcx>)
-> Option<InitIndex>
{
let mpi = self.move_data.rev_lookup.find_local(local);
let ii = &self.move_data.init_path_map[mpi];
for &index in ii {
if flow_state.ever_inits.contains(index) {
return Some(index);
}
}
return None;
}
/// Adds the place into the used mutable variables set
fn add_used_mut<'d>(
&mut self,
@ -1900,18 +1911,13 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
place: Place::Local(local),
is_local_mutation_allowed,
} => {
if is_local_mutation_allowed != LocalMutationIsAllowed::Yes {
// If the local may be initialized, and it is now currently being
// mutated, then it is justified to be annotated with the `mut`
// keyword, since the mutation may be a possible reassignment.
let mpi = self.move_data.rev_lookup.find_local(*local);
let ii = &self.move_data.init_path_map[mpi];
for &index in ii {
if flow_state.ever_inits.contains(index) {
self.used_mut.insert(*local);
break;
}
}
// If the local may have been initialized, and it is now currently being
// mutated, then it is justified to be annotated with the `mut`
// keyword, since the mutation may be a possible reassignment.
if is_local_mutation_allowed != LocalMutationIsAllowed::Yes &&
self.is_local_ever_initialized(*local, flow_state).is_some()
{
self.used_mut.insert(*local);
}
}
RootPlace {