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GTimothyGTimothy
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Fix 'assign to data in an index of' collection suggestions
splits the large triple suggestion into three sets them to MaybeIncorrect automatically determines the required borrowing to use.
1 parent 5d04477 commit abb512e

1 file changed

Lines changed: 80 additions & 57 deletions

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‎compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs‎

Lines changed: 80 additions & 57 deletions
Original file line numberDiff line numberDiff line change
@@ -668,7 +668,9 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
668668
err: &'a mut Diag<'infcx>,
669669
ty: Ty<'tcx>,
670670
suggested: bool,
671+
infcx: &'a rustc_infer::infer::InferCtxt<'tcx>,
671672
}
673+
672674
impl<'a, 'infcx, 'tcx> Visitor<'tcx> for SuggestIndexOperatorAlternativeVisitor<'a, 'infcx, 'tcx> {
673675
fn visit_stmt(&mut self, stmt: &'tcx hir::Stmt<'tcx>) {
674676
hir::intravisit::walk_stmt(self, stmt);
@@ -679,81 +681,101 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
679681
return;
680682
}
681683
};
684+
685+
/// Taken straight from https://doc.rust-lang.org/nightly/nightly-rustc/clippy_utils/fn.peel_hir_ty_refs.html
686+
/// Adapted to mid using https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.Ty.html#method.peel_refs
687+
/// Simplified to counting only
688+
/// Peels off all references on the type. Returns the number of references
689+
/// removed.
690+
fn count_ty_refs<'tcx>(ty: Ty<'tcx>) -> usize {
691+
let mut count = 0;
692+
let mut ty = ty;
693+
while let ty::Ref(_, inner_ty, _) = ty.kind() {
694+
ty = *inner_ty;
695+
count += 1;
696+
}
697+
count
698+
}
682699
if let hir::ExprKind::Assign(place, rv, _sp) = expr.kind
683700
&& let hir::ExprKind::Index(val, index, _) = place.kind
684701
&& (expr.span == self.assign_span || place.span == self.assign_span)
685702
{
686-
// val[index] = rv;
687-
// ---------- place
688-
self.err.multipart_suggestions(
703+
let ref_depth_difference: usize;
704+
let _index_is_copy_clone: bool;
705+
706+
if let Some(index_ty) =
707+
self.infcx.tcx.typeck(val.hir_id.owner.def_id).expr_ty_opt(index)
708+
{
709+
// we know ty is a map, with a key type at walk distance 2.
710+
let key_type = self.ty.walk().nth(1).unwrap().expect_ty();
711+
let key_ref_depth = count_ty_refs(key_type);
712+
713+
let index_ref_depth = count_ty_refs(index_ty);
714+
ref_depth_difference = index_ref_depth - key_ref_depth; //index should
715+
//be deeper than key
716+
} else {
717+
// no type ?
718+
return;
719+
};
720+
721+
// remove the exessive referencing if necessary, but get_mut requires a ref
722+
let (prefix, gm_prefix) = match ref_depth_difference {
723+
0 => (String::new(), String::from("&")),
724+
n => ("*".repeat(n), "*".repeat(n - 1)),
725+
};
726+
727+
self.err.multipart_suggestion(
728+
format!("use `.insert()` to insert a value into a `{}`", self.ty),
729+
vec![
730+
// val.insert(index, rv);
731+
(
732+
val.span.shrink_to_hi().with_hi(index.span.lo()),
733+
format!(".insert({prefix}"),
734+
),
735+
(index.span.shrink_to_hi().with_hi(rv.span.lo()), ", ".to_string()),
736+
(rv.span.shrink_to_hi(), ")".to_string()),
737+
],
738+
Applicability::MaybeIncorrect,
739+
);
740+
self.err.multipart_suggestion(
689741
format!(
690-
"use `.insert()` to insert a value into a `{}`, `.get_mut()` \
691-
to modify it, or the entry API for more flexibility",
742+
"use `.get_mut()` to modify an existing key in a `{}`",
692743
self.ty,
693744
),
694745
vec![
695-
vec![
696-
// val.insert(index, rv);
697-
(
698-
val.span.shrink_to_hi().with_hi(index.span.lo()),
699-
".insert(".to_string(),
700-
),
701-
(
702-
index.span.shrink_to_hi().with_hi(rv.span.lo()),
703-
", ".to_string(),
704-
),
705-
(rv.span.shrink_to_hi(), ")".to_string()),
706-
],
707-
vec![
708-
// if let Some(v) = val.get_mut(index) { *v = rv; }
709-
(val.span.shrink_to_lo(), "if let Some(val) = ".to_string()),
710-
(
711-
val.span.shrink_to_hi().with_hi(index.span.lo()),
712-
".get_mut(".to_string(),
713-
),
714-
(
715-
index.span.shrink_to_hi().with_hi(place.span.hi()),
716-
") { *val".to_string(),
717-
),
718-
(rv.span.shrink_to_hi(), "; }".to_string()),
719-
],
720-
vec![
721-
// let x = val.entry(index).or_insert(rv);
722-
(val.span.shrink_to_lo(), "let val = ".to_string()),
723-
(
724-
val.span.shrink_to_hi().with_hi(index.span.lo()),
725-
".entry(".to_string(),
726-
),
727-
(
728-
index.span.shrink_to_hi().with_hi(rv.span.lo()),
729-
").or_insert(".to_string(),
730-
),
731-
(rv.span.shrink_to_hi(), ")".to_string()),
732-
],
746+
// if let Some(v) = val.get_mut(index) { *v = rv; }
747+
(val.span.shrink_to_lo(), "if let Some(val) = ".to_string()),
748+
(
749+
val.span.shrink_to_hi().with_hi(index.span.lo()),
750+
format!(".get_mut({gm_prefix}"),
751+
),
752+
(
753+
index.span.shrink_to_hi().with_hi(place.span.hi()),
754+
") { *val".to_string(),
755+
),
756+
(rv.span.shrink_to_hi(), "; }".to_string()),
733757
],
734-
Applicability::MachineApplicable,
758+
Applicability::MaybeIncorrect,
735759
);
736-
self.suggested = true;
737-
} else if let hir::ExprKind::MethodCall(_path, receiver, _, sp) = expr.kind
738-
&& let hir::ExprKind::Index(val, index, _) = receiver.kind
739-
&& receiver.span == self.assign_span
740-
{
741-
// val[index].path(args..);
742760
self.err.multipart_suggestion(
743-
format!("to modify a `{}` use `.get_mut()`", self.ty),
761+
format!(
762+
"use the entry API to modify a `{}` for more flexibility",
763+
self.ty
764+
),
744765
vec![
745-
(val.span.shrink_to_lo(), "if let Some(val) = ".to_string()),
766+
// let x = val.entry(index).insert_entry(rv);
767+
(val.span.shrink_to_lo(), "let val = ".to_string()),
746768
(
747769
val.span.shrink_to_hi().with_hi(index.span.lo()),
748-
".get_mut(".to_string(),
770+
format!(".entry({prefix}"),
749771
),
750772
(
751-
index.span.shrink_to_hi().with_hi(receiver.span.hi()),
752-
") { val".to_string(),
773+
index.span.shrink_to_hi().with_hi(rv.span.lo()),
774+
").insert_entry(".to_string(),
753775
),
754-
(sp.shrink_to_hi(), "; }".to_string()),
776+
(rv.span.shrink_to_hi(), ")".to_string()),
755777
],
756-
Applicability::MachineApplicable,
778+
Applicability::MaybeIncorrect,
757779
);
758780
self.suggested = true;
759781
}
@@ -768,6 +790,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
768790
err,
769791
ty,
770792
suggested: false,
793+
infcx: self.infcx,
771794
};
772795
v.visit_body(&body);
773796
if !v.suggested {

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