diff -r 8392405ab038 -r 7e0f345e64a8 langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Resolve.java
--- a/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Resolve.java	Wed Jul 05 20:52:37 2017 +0200
+++ b/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Resolve.java	Wed Oct 07 15:53:38 2015 +0530
@@ -2426,7 +2426,9 @@
                 return spMethod;
             }
         };
-        polymorphicSignatureScope.enter(msym);
+        if (!mtype.isErroneous()) { // Cache only if kosher.
+            polymorphicSignatureScope.enter(msym);
+        }
         return msym;
     }