fixed #360

1 files changed, 7 insertions, 1 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Infer.scala b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
index 5e16274eed..c4eba1f7b5 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Infer.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
@@ -147,7 +147,13 @@ trait Infer {
 //      throw new DeferredNoInstance(() =>
 //        "no solution exists for constraints"+(tvars map boundsString))
     }
-    for (val tvar <- tvars) assert(tvar.constr.inst != tvar, tvar.origin)
+    for (val tvar <- tvars)
+      if (tvar.constr.inst == tvar)
+        if (tvar.origin.typeSymbol.info eq ErrorType) {
+          // this can happen if during solving a cyclic type paramater
+          // such as T <: T gets completed. See #360
+          tvar.constr.inst = ErrorType
+        } else assert(false, tvar.origin)
     tvars map instantiate
   }