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is_union returns ty to avoid computing it twice

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This commit is contained in:
Santiago Pastorino 2019-05-28 15:18:37 +02:00
parent 7da118581c
commit 1b86bd73cd
1 changed files with 25 additions and 23 deletions
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48
src/librustc_mir/borrow_check/conflict_errors.rs
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@ -595,11 +595,9 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
) -> (String, String, String, String) {
// Define a small closure that we can use to check if the type of a place
// is a union.
let is_union = |place: &Place<'tcx>| -> bool {
place.ty(self.mir, self.infcx.tcx).ty
.ty_adt_def()
.map(|adt| adt.is_union())
.unwrap_or(false)
let union_ty = |place: &Place<'tcx>| -> Option<Ty<'tcx>> {
let ty = place.ty(self.mir, self.infcx.tcx).ty;
ty.ty_adt_def().filter(|adt| adt.is_union()).map(|_| ty)
};
// Start with an empty tuple, so we can use the functions on `Option` to reduce some
@ -619,7 +617,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
let mut current = first_borrowed_place;
while let Place::Projection(box Projection { base, elem }) = current {
match elem {
ProjectionElem::Field(field, _) if is_union(base) => {
ProjectionElem::Field(field, _) if union_ty(base).is_some() => {
return Some((base, field));
},
_ => current = base,
@ -632,25 +630,29 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
// borrowed place and look for a access to a different field of the same union.
let mut current = second_borrowed_place;
while let Place::Projection(box Projection { base, elem }) = current {
match elem {
ProjectionElem::Field(field, _) if {
is_union(base) && field != target_field && base == target_base
} => {
let desc_base = self.describe_place(base)
.unwrap_or_else(|| "_".to_owned());
let desc_first = self.describe_place(first_borrowed_place)
.unwrap_or_else(|| "_".to_owned());
let desc_second = self.describe_place(second_borrowed_place)
.unwrap_or_else(|| "_".to_owned());
if let ProjectionElem::Field(field, _) = elem {
if let Some(union_ty) = union_ty(base) {
if field != target_field && base == target_base {
let desc_base =
self.describe_place(base).unwrap_or_else(|| "_".to_owned());
let desc_first = self
.describe_place(first_borrowed_place)
.unwrap_or_else(|| "_".to_owned());
let desc_second = self
.describe_place(second_borrowed_place)
.unwrap_or_else(|| "_".to_owned());
// Also compute the name of the union type, eg. `Foo` so we
// can add a helpful note with it.
let ty = base.ty(self.mir, self.infcx.tcx).ty;
return Some((desc_base, desc_first, desc_second, ty.to_string()));
},
_ => current = base,
return Some((
desc_base,
desc_first,
desc_second,
union_ty.to_string(),
));
}
}
}
current = base;
}
None
})