src/java.base/share/classes/jdk/internal/module/ModuleBootstrap.java

rev 16338 : 8171400: Move checking of duplicate packages in the boot layer to link time
Reviewed-by: alanb

@@ -306,10 +306,27 @@
                         fail(name + ": cannot be loaded from application module path");
                 }
             }
         }
 
+        // if needed check that there are no split packages in the set of
+        // resolved modules for the boot layer
+        if (SystemModules.hasSplitPackages() || needPostResolutionChecks) {
+                Map<String, String> packageToModule = new HashMap<>();
+                for (ResolvedModule resolvedModule : cf.modules()) {
+                    ModuleDescriptor descriptor =
+                        resolvedModule.reference().descriptor();
+                    String name = descriptor.name();
+                    for (String p : descriptor.packages()) {
+                        String other = packageToModule.putIfAbsent(p, name);
+                        if (other != null) {
+                            fail("Package " + p + " in both module "
+                                 + name + " and module " + other);
+                        }
+                    }
+                }
+            }
 
         long t4 = System.nanoTime();
 
         // define modules to VM/runtime
         Layer bootLayer = Layer.empty().defineModules(cf, clf);