mv utility methods into separate module

[rust.git] / compiler / rustc_infer / src / infer / nll_relate / mod.rs

diff --git a/compiler/rustc_infer/src/infer/nll_relate/mod.rs b/compiler/rustc_infer/src/infer/nll_relate/mod.rs
index 600f94f095eace0056fc0af4292245a197946f0f..167a82d4499a188603895a21b2bfe9349d628341 100644 (file)
--- a/compiler/rustc_infer/src/infer/nll_relate/mod.rs
+++ b/compiler/rustc_infer/src/infer/nll_relate/mod.rs
@@ -556,8 +556,9 @@ fn relate_with_variance<T: Relate<'tcx>>(
         self.ambient_variance_info = self.ambient_variance_info.xform(info);
 
         debug!(?self.ambient_variance);
-
-        let r = self.relate(a, b)?;
+        // In a bivariant context this always succeeds.
+        let r =
+            if self.ambient_variance == ty::Variance::Bivariant { a } else { self.relate(a, b)? };
 
         self.ambient_variance = old_ambient_variance;