diff options
| -rw-r--r-- | compiler/rustc_infer/src/infer/canonical/mod.rs | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/compiler/rustc_infer/src/infer/canonical/mod.rs b/compiler/rustc_infer/src/infer/canonical/mod.rs index ba0ce16bb81..e59715b706b 100644 --- a/compiler/rustc_infer/src/infer/canonical/mod.rs +++ b/compiler/rustc_infer/src/infer/canonical/mod.rs @@ -41,7 +41,7 @@ impl<'tcx> InferCtxt<'tcx> { /// inference variables and applies it to the canonical value. /// Returns both the instantiated result *and* the substitution S. /// - /// This is only meant to be invoked as part of constructing an + /// This can be invoked as part of constructing an /// inference context at the start of a query (see /// `InferCtxtBuilder::build_with_canonical`). It basically /// brings the canonical value "into scope" within your new infcx. @@ -63,8 +63,11 @@ impl<'tcx> InferCtxt<'tcx> { // in them, so this code has no effect, but it is looking // forward to the day when we *do* want to carry universes // through into queries. - let universes: IndexVec<ty::UniverseIndex, _> = std::iter::once(ty::UniverseIndex::ROOT) - .chain((0..canonical.max_universe.as_u32()).map(|_| self.create_next_universe())) + // + // Instantiate the root-universe content into the current universe, + // and create fresh universes for the higher universes. + let universes: IndexVec<ty::UniverseIndex, _> = std::iter::once(self.universe()) + .chain((1..=canonical.max_universe.as_u32()).map(|_| self.create_next_universe())) .collect(); let canonical_inference_vars = |