Merge #8921

8921: Resolve any lifetime variables to 'static after inference r=flodiebold a=flodiebold

Chalk's unification can sometimes create lifetime variables, which we
currently don't really deal with, but at least we don't want to leak
them outside of inference.

Should fix #8919.

Co-authored-by: Florian Diebold <[email protected]>

1 files changed, 13 insertions, 1 deletions

diff --git a/crates/hir_ty/src/infer/unify.rs b/crates/hir_ty/src/infer/unify.rs
index 21d3fb54e..f8233cac3 100644
--- a/crates/hir_ty/src/infer/unify.rs
+++ b/crates/hir_ty/src/infer/unify.rs
@@ -435,7 +435,7 @@ mod resolve {
     use super::InferenceTable;
     use crate::{
         ConcreteConst, Const, ConstData, ConstValue, DebruijnIndex, GenericArg, InferenceVar,
-        Interner, Ty, TyVariableKind, VariableKind,
+        Interner, Lifetime, Ty, TyVariableKind, VariableKind,
     };
     use chalk_ir::{
         cast::Cast,
@@ -524,5 +524,17 @@ mod resolve {
             };
             Ok(result)
         }
+
+        fn fold_inference_lifetime(
+            &mut self,
+            _var: InferenceVar,
+            _outer_binder: DebruijnIndex,
+        ) -> Fallible<Lifetime> {
+            // fall back all lifetimes to 'static -- currently we don't deal
+            // with any lifetimes, but we can sometimes get some lifetime
+            // variables through Chalk's unification, and this at least makes
+            // sure we don't leak them outside of inference
+            Ok(crate::static_lifetime())
+        }
     }
 }