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On TerminatorKind::DropAndReplace still handle unused_mut correctly #61446

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Merged
merged 7 commits into from
Jun 4, 2019
Merged

On TerminatorKind::DropAndReplace still handle unused_mut correctly #61446

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911d205
On TerminatorKind::DropAndReplace still handle unused_mut correctly
czipperz Jun 1, 2019
c25b3df
Elide lifetimes not used
czipperz Jun 1, 2019
a39fffe
Add self parameter
czipperz Jun 2, 2019
0a6a5c8
Move debug statement into statement visitor
czipperz Jun 2, 2019
2a3b29e
Add anonymous lifetime to Place parameter
czipperz Jun 2, 2019
7feeaf0
Add test
czipperz Jun 2, 2019
fea2cdb
Use a type implementing Drop
czipperz Jun 3, 2019
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44 changes: 23 additions & 21 deletions src/librustc_mir/borrow_check/used_muts.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -52,6 +52,24 @@ struct GatherUsedMutsVisitor<'visit, 'cx: 'visit, 'gcx: 'tcx, 'tcx: 'cx> {
mbcx: &'visit mut MirBorrowckCtxt<'cx, 'gcx, 'tcx>,
}

impl<'visit, 'cx, 'gcx, 'tcx> GatherUsedMutsVisitor<'visit, 'cx, 'gcx, 'tcx> {
fn remove_never_initialized_mut_locals(into: &Place) {
// Remove any locals that we found were initialized from the
// `never_initialized_mut_locals` set. At the end, the only remaining locals will
// be those that were never initialized - we will consider those as being used as
// they will either have been removed by unreachable code optimizations; or linted
// as unused variables.
if let Some(local) = into.base_local() {
debug!(
"visit_statement: statement={:?} local={:?} \
never_initialized_mut_locals={:?}",
statement, local, self.never_initialized_mut_locals
);
let _ = self.never_initialized_mut_locals.remove(&local);
}
}
}

impl<'visit, 'cx, 'gcx, 'tcx> Visitor<'tcx> for GatherUsedMutsVisitor<'visit, 'cx, 'gcx, 'tcx> {
fn visit_terminator_kind(
&mut self,
Expand All @@ -61,14 +79,10 @@ impl<'visit, 'cx, 'gcx, 'tcx> Visitor<'tcx> for GatherUsedMutsVisitor<'visit, 'c
debug!("visit_terminator_kind: kind={:?}", kind);
match &kind {
TerminatorKind::Call { destination: Some((into, _)), .. } => {
if let Some(local) = into.base_local() {
debug!(
"visit_terminator_kind: kind={:?} local={:?} \
never_initialized_mut_locals={:?}",
kind, local, self.never_initialized_mut_locals
);
let _ = self.never_initialized_mut_locals.remove(&local);
}
self.remove_never_initialized_mut_locals(&into);
},
TerminatorKind::DropAndReplace { location, .. } => {
self.remove_never_initialized_mut_locals(&location);
},
_ => {},
}
Expand All @@ -81,19 +95,7 @@ impl<'visit, 'cx, 'gcx, 'tcx> Visitor<'tcx> for GatherUsedMutsVisitor<'visit, 'c
) {
match &statement.kind {
StatementKind::Assign(into, _) => {
// Remove any locals that we found were initialized from the
// `never_initialized_mut_locals` set. At the end, the only remaining locals will
// be those that were never initialized - we will consider those as being used as
// they will either have been removed by unreachable code optimizations; or linted
// as unused variables.
if let Some(local) = into.base_local() {
debug!(
"visit_statement: statement={:?} local={:?} \
never_initialized_mut_locals={:?}",
statement, local, self.never_initialized_mut_locals
);
let _ = self.never_initialized_mut_locals.remove(&local);
}
self.remove_never_initialized_mut_locals(into);
},
_ => {},
}
Expand Down