Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

is_union returns ty to avoid computing it twice #61261

Merged
merged 2 commits into from
May 29, 2019
+24 −27
Merged

is_union returns ty to avoid computing it twice #61261

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
1b86bd7
is_union returns ty to avoid computing it twice
spastorino May 28, 2019
bb94fc0
Use closure to avoid self.describe_place(...).unwrap_or_else(...) rep…
spastorino May 28, 2019
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
51 changes: 24 additions & 27 deletions src/librustc_mir/borrow_check/conflict_errors.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -595,12 +595,11 @@ 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)
};
let describe_place = |place| self.describe_place(place).unwrap_or_else(|| "_".to_owned());

// Start with an empty tuple, so we can use the functions on `Option` to reduce some
// code duplication (particularly around returning an empty description in the failure
Expand All @@ -619,7 +618,7 @@ 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,
Expand All @@ -632,34 +631,32 @@ 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());

// 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,
if let ProjectionElem::Field(field, _) = elem {
if let Some(union_ty) = union_ty(base) {
if field != target_field && base == target_base {
return Some((
describe_place(base),
describe_place(first_borrowed_place),
describe_place(second_borrowed_place),
union_ty.to_string(),
));
}
}
}

current = base;
}
None
})
.unwrap_or_else(|| {
// If we didn't find a field access into a union, or both places match, then
// only return the description of the first place.
let desc_place = self.describe_place(first_borrowed_place)
.unwrap_or_else(|| "_".to_owned());
(desc_place, "".to_string(), "".to_string(), "".to_string())
(
describe_place(first_borrowed_place),
"".to_string(),
"".to_string(),
"".to_string(),
)
})
}

Expand Down