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generalize `find_constraint_paths_between_regions`

This commit is contained in:
Niko Matsakis 2018-07-03 05:59:08 -04:00
parent 09f431fad5
commit dddd4075b1
1 changed files with 10 additions and 17 deletions
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27
src/librustc_mir/borrow_check/nll/region_infer/error_reporting.rs
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@ -64,13 +64,13 @@ impl<'tcx> RegionInferenceContext<'tcx> {
fn find_constraint_paths_between_regions(
&self,
from_region: RegionVid,
to_region: RegionVid,
target_test: impl Fn(RegionVid) -> bool,
) -> Vec<Vec<ConstraintIndex>> {
let mut results = vec![];
self.find_constraint_paths_between_regions_helper(
from_region,
from_region,
to_region,
&target_test,
&mut FxHashSet::default(),
&mut vec![],
&mut results,
@ -83,7 +83,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
&self,
from_region: RegionVid,
current_region: RegionVid,
to_region: RegionVid,
target_test: &impl Fn(RegionVid) -> bool,
visited: &mut FxHashSet<RegionVid>,
stack: &mut Vec<ConstraintIndex>,
results: &mut Vec<Vec<ConstraintIndex>>,
@ -96,18 +96,11 @@ impl<'tcx> RegionInferenceContext<'tcx> {
}
// Check if we reached the region we were looking for.
if current_region == to_region {
// Unless we started out searching for `'a ~> 'a`, which shouldn't have caused
// en error, then we must have traversed at least *some* constraint:
assert!(!stack.is_empty());
// The first constraint should be like `X: from_region`.
assert_eq!(self.constraints[stack[0]].sub, from_region);
// The last constraint should be like `to_region: Y`.
assert_eq!(self.constraints[*stack.last().unwrap()].sup, to_region);
results.push(stack.clone());
if target_test(current_region) {
if !stack.is_empty() {
assert_eq!(self.constraints[stack[0]].sub, from_region);
results.push(stack.clone());
}
return;
}
@ -118,7 +111,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
self.find_constraint_paths_between_regions_helper(
from_region,
self.constraints[constraint].sup,
to_region,
target_test,
visited,
stack,
results,
@ -229,7 +222,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
};
// Find all paths
let constraint_paths = self.find_constraint_paths_between_regions(outlived_fr, fr);
let constraint_paths = self.find_constraint_paths_between_regions(outlived_fr, |r| r == fr);
debug!("report_error: constraint_paths={:#?}", constraint_paths);
// Find the shortest such path.