src/jdk.jdeps/share/classes/com/sun/tools/jdeps/JdepsTask.java

@@ -481,10 +481,11 @@
                 showHelp();
                 return EXIT_CMDERR;
             }
             if (options.checkModuleDeps != null && !inputArgs.isEmpty()) {
                 reportError("err.invalid.module.option", inputArgs, "--check");
+                return EXIT_CMDERR;
             }
 
             boolean ok = run();
             return ok ? EXIT_OK : EXIT_ERROR;
         } catch (BadArgs|UncheckedBadArgs e) {

@@ -674,21 +675,33 @@
     private String sortPath(Deque<Archive> path) {
         return path.peekFirst().getName();
     }
 
     private boolean genModuleInfo(JdepsConfiguration config) throws IOException {
+        // check if any JAR file contains unnamed package
+        for (String arg : inputArgs) {
+            Optional<String> classInUnnamedPackage =
+                ClassFileReader.newInstance(Paths.get(arg))
+                    .entries().stream()
+                    .filter(n -> n.endsWith(".class"))
+                    .filter(cn -> toPackageName(cn).isEmpty())
+                    .findFirst();
+
+            if (classInUnnamedPackage.isPresent()) {
+                if (classInUnnamedPackage.get().equals("module-info.class")) {
+                    reportError("err.genmoduleinfo.not.jarfile", arg);
+                } else {
+                    reportError("err.genmoduleinfo.unnamed.package", arg);
+                }
+                return false;
+            }
+        }
+
         ModuleInfoBuilder builder
             = new ModuleInfoBuilder(config, inputArgs, options.genModuleInfo);
         boolean ok = builder.run();
 
-        builder.modules().forEach(module -> {
-            if (module.packages().contains("")) {
-                reportError("ERROR: %s contains unnamed package.  " +
-                    "module-info.java not generated%n", module.getPathName());
-            }
-        });
-
         if (!ok && !options.nowarning) {
             log.println("ERROR: missing dependencies");
             builder.visitMissingDeps(
                 new Analyzer.Visitor() {
                     @Override

@@ -701,10 +714,15 @@
                 });
         }
         return ok;
     }
 
+    private String toPackageName(String name) {
+        int i = name.lastIndexOf('/');
+        return i > 0 ? name.replace('/', '.').substring(0, i) : "";
+    }
+
     /**
      * Returns a filter used during dependency analysis
      */
     private JdepsFilter dependencyFilter(JdepsConfiguration config) {
         // Filter specified by -filter, -package, -regex, and -requires options