diff -r 32c50b5f70b5 -r c8acc254b6d7 src/share/classes/com/sun/tools/javac/comp/Infer.java
--- a/src/share/classes/com/sun/tools/javac/comp/Infer.java	Tue Jun 04 11:31:12 2013 +0100
+++ b/src/share/classes/com/sun/tools/javac/comp/Infer.java	Tue Jun 04 11:34:31 2013 +0100
@@ -218,8 +218,8 @@
         //we need to skip capture?
         Warner retWarn = new Warner();
         if (!resultInfo.checkContext.compatible(qtype1, resultInfo.checkContext.inferenceContext().asFree(to), retWarn) ||
-                //unchecked conversion is not allowed
-                retWarn.hasLint(Lint.LintCategory.UNCHECKED)) {
+                //unchecked conversion is not allowed in source 7 mode
+                (!allowGraphInference && retWarn.hasLint(Lint.LintCategory.UNCHECKED))) {
             throw inferenceException
                     .setMessage("infer.no.conforming.instance.exists",
                     inferenceContext.restvars(), mt.getReturnType(), to);