diff options
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/rustc_borrowck/src/region_infer/opaque_types.rs | 35 |
1 files changed, 20 insertions, 15 deletions
diff --git a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs index 8c9de5210cd..1073ea40694 100644 --- a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs +++ b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs @@ -225,21 +225,26 @@ impl<'tcx> RegionInferenceContext<'tcx> { // Find something that we can name let upper_bound = self.approx_universal_upper_bound(vid); - let upper_bound = &self.definitions[upper_bound]; - match upper_bound.external_name { - Some(reg) => reg, - None => { - // Nothing exact found, so we pick the first one that we find. - let scc = self.constraint_sccs.scc(vid); - for vid in self.rev_scc_graph.as_ref().unwrap().upper_bounds(scc) { - match self.definitions[vid].external_name { - None => {} - Some(region) if region.is_static() => {} - Some(region) => return region, - } - } - region - } + if let Some(universal_region) = self.definitions[upper_bound].external_name { + return universal_region; + } + + // Nothing exact found, so we pick a named upper bound, if there's only one. + // If there's >1 universal region, then we probably are dealing w/ an intersection + // region which cannot be mapped back to a universal. + // FIXME: We could probably compute the LUB if there is one. + let scc = self.constraint_sccs.scc(vid); + let upper_bounds: Vec<_> = self + .rev_scc_graph + .as_ref() + .unwrap() + .upper_bounds(scc) + .filter_map(|vid| self.definitions[vid].external_name) + .filter(|r| !r.is_static()) + .collect(); + match &upper_bounds[..] { + [universal_region] => *universal_region, + _ => region, } } _ => region, |