user0/rust
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Fix unused 'mut' warning for capture's root variable

Browse source
This commit is contained in:
Aman Arora 2020-12-15 23:00:19 -05:00
parent 0897db5609
commit 604cbdcfdd
4 changed files with 77 additions and 23 deletions
Download patch file Download diff file Expand all files Collapse all files

37
compiler/rustc_mir/src/borrow_check/mod.rs
View file

@ -1369,13 +1369,38 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
fn propagate_closure_used_mut_upvar(&mut self, operand: &Operand<'tcx>) {
let propagate_closure_used_mut_place = |this: &mut Self, place: Place<'tcx>| {
if !place.projection.is_empty() {
if let Some(field) = this.is_upvar_field_projection(place.as_ref()) {
this.used_mut_upvars.push(field);
}
} else {
this.used_mut.insert(place.local);
// We have three possiblities here:
// a. We are modifying something through a mut-ref
// b. We are modifying something that is local to our parent
// c. Current body is a nested clsoure, and we are modifying path starting from
// a Place captured by our parent closure.
// Handle (c), the path being modified is exactly the path captured by our parent
if let Some(field) = this.is_upvar_field_projection(place.as_ref()) {
this.used_mut_upvars.push(field);
return;
}
for (place_ref, proj) in place.iter_projections().rev() {
// Handle (a)
if proj == ProjectionElem::Deref {
match place_ref.ty(this.body(), this.infcx.tcx).ty.kind() {
// We aren't modifying a variable directly
ty::Ref(_, _, hir::Mutability::Mut) => return,
_ => {}
}
}
// Handle (c)
if let Some(field) = this.is_upvar_field_projection(place_ref) {
this.used_mut_upvars.push(field);
return;
}
}
// Handle(b)
this.used_mut.insert(place.local);
};
// This relies on the current way that by-value