--- a/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Modules.java	Tue Feb 14 16:18:38 2017 +0300
+++ b/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Modules.java	Tue Feb 14 15:45:17 2017 -0800
@@ -996,8 +996,18 @@
             }
             ListBuffer<ClassSymbol> impls = new ListBuffer<>();
             for (JCExpression implName : tree.implNames) {
-                Type it = attr.attribType(implName, env, syms.objectType);
+                Type it;
+                boolean prevVisitingServiceImplementation = env.info.visitingServiceImplementation;
+                try {
+                    env.info.visitingServiceImplementation = true;
+                    it = attr.attribType(implName, env, syms.objectType);
+                } finally {
+                    env.info.visitingServiceImplementation = prevVisitingServiceImplementation;
+                }
                 ClassSymbol impl = (ClassSymbol) it.tsym;
+                if ((impl.flags_field & PUBLIC) == 0) {
+                    log.error(implName.pos(), Errors.NotDefPublic(impl, impl.location()));
+                }
                 //find provider factory:
                 MethodSymbol factory = factoryMethod(impl);
                 if (factory != null) {