mikros/rust
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

convert LateBoundRegionsCollector to track a debruijn index

Browse Source 
Co-authored-by: csmoe <35686186+csmoe@users.noreply.github.com>
This commit is contained in:
Niko Matsakis 2018-05-28 10:24:01 -04:00
parent 4aeb6efb6d
commit 06b2a3fbdb
1 changed files with 15 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
src/librustc/ty/fold.rs
View File

@ -671,17 +671,26 @@ impl<'tcx> TypeVisitor<'tcx> for HasTypeFlagsVisitor {
}
}
/// Collects all the late-bound regions it finds into a hash set.
/// Collects all the late-bound regions at the innermost binding level
/// into a hash set.
struct LateBoundRegionsCollector {
current_depth: u32,
current_index: ty::DebruijnIndex,
regions: FxHashSet<ty::BoundRegion>,
/// If true, we only want regions that are known to be
/// "constrained" when you equate this type with another type. In
/// partcular, if you have e.g. `&'a u32` and `&'b u32`, equating
/// them constraints `'a == 'b`. But if you have `<&'a u32 as
/// Trait>::Foo` and `<&'b u32 as Trait>::Foo`, normalizing those
/// types may mean that `'a` and `'b` don't appear in the results,
/// so they are not considered *constrained*.
just_constrained: bool,
}
impl LateBoundRegionsCollector {
fn new(just_constrained: bool) -> Self {
LateBoundRegionsCollector {
current_depth: 1,
current_index: ty::DebruijnIndex::INNERMOST,
regions: FxHashSet(),
just_constrained,
}
@ -690,9 +699,9 @@ impl LateBoundRegionsCollector {
impl<'tcx> TypeVisitor<'tcx> for LateBoundRegionsCollector {
fn visit_binder<T: TypeFoldable<'tcx>>(&mut self, t: &Binder<T>) -> bool {
self.current_depth += 1;
self.current_index.shift_in(1);
let result = t.super_visit_with(self);
self.current_depth -= 1;
self.current_index.shift_out(1);
result
}
@ -712,7 +721,7 @@ impl<'tcx> TypeVisitor<'tcx> for LateBoundRegionsCollector {
fn visit_region(&mut self, r: ty::Region<'tcx>) -> bool {
match *r {
ty::ReLateBound(debruijn, br) if debruijn.depth == self.current_depth => {
ty::ReLateBound(debruijn, br) if debruijn == self.current_index => {
self.regions.insert(br);
}
_ => { }