src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TypeEnter.java

*** 672,683 ****
--- 672,686 ----
              ClassSymbol sym = tree.sym;
              ClassType ct = (ClassType)sym.type;
              // Determine supertype.
              Type supertype;
              JCExpression extending;
+             final boolean isValueType = (tree.mods.flags & Flags.VALUE) != 0;
  
              if (tree.extending != null) {
+                 if (isValueType)
+                     log.error(tree.pos(), Errors.ValueMayNotExtend);
                  extending = clearTypeParams(tree.extending);
                  supertype = attr.attribBase(extending, baseEnv, true, false, true);
              } else {
                  extending = null;
                  supertype = ((tree.mods.flags & Flags.ENUM) != 0)
*** 961,970 ****
--- 964,977 ----
                  (types.supertype(tree.sym.type).tsym.flags() & Flags.ENUM) == 0) {
                  addEnumMembers(tree, env);
              }
              memberEnter.memberEnter(tree.defs, env);
  
+             if ((tree.mods.flags & (Flags.VALUE | Flags.INTERFACE)) == Flags.VALUE && !tree.sym.type.hasTag(ERROR)) {
+                 addValueMembers(tree, env);
+             }
+ 
              if (tree.sym.isAnnotationType()) {
                  Assert.check(tree.sym.isCompleted());
                  tree.sym.setAnnotationTypeMetadata(new AnnotationTypeMetadata(tree.sym, annotate.annotationTypeSourceCompleter()));
              }
          }
*** 1001,1010 ****
--- 1008,1104 ----
                            null, //make.Block(0, Tree.emptyList.prepend(make.Return(make.Ident(names._null)))),
                            null);
              memberEnter.memberEnter(valueOf, env);
          }
  
+         /** Add the implicit members for a value type to the parse tree and the symbol table.
+          */
+         private void addValueMembers(JCClassDecl tree, Env<AttrContext> env) {
+ 
+             boolean requireHashCode = true, requireEquals = true, requireToString = true;
+ 
+             for (JCTree def : tree.defs) {
+                 if (def.getTag() == METHODDEF) {
+                     JCMethodDecl methodDecl = (JCMethodDecl)def;
+                     if (methodDecl.sym != null
+                             && methodDecl.sym.type != null
+                             && !methodDecl.sym.type.isErroneous()
+                             && (methodDecl.sym.flags() & STATIC) == 0) {
+                         final List<Type> parameterTypes = methodDecl.sym.type.getParameterTypes();
+                         switch (parameterTypes.size()) {
+                             case 0:
+                                 String name = methodDecl.name.toString();
+                                 if (name.equals("hashCode"))
+                                     requireHashCode = false;
+                                 else if (name.equals("toString"))
+                                     requireToString = false;
+                                 break;
+                             case 1:
+                                 name = methodDecl.name.toString();
+                                 if (name.equals("equals") && parameterTypes.head.tsym == syms.objectType.tsym)
+                                     requireEquals = false;
+                                 break;
+                         }
+                     }
+                 }
+             }
+ 
+             make.at(tree.pos);
+             // Make a body comprising { throw new RuntimeException(""Internal error: This method must have been replaced by javac"); }
+             JCBlock body = make.Block(Flags.SYNTHETIC, List.of(make.Throw(
+                     make.NewClass(null,
+                             null,
+                             make.Ident(names.fromString("RuntimeException")),
+                             List.of(make.Literal(CLASS, "Internal error: This method must have been replaced by javac")),
+                             null))));
+ 
+             if (requireHashCode) {
+                 // public int hashCode() { throw new RuntimeException(message); }
+                 JCMethodDecl hashCode = make.
+                         MethodDef(make.Modifiers(Flags.PUBLIC | Flags.FINAL),
+                                 names.hashCode,
+                                 make.TypeIdent(TypeTag.INT),
+                                 List.nil(),
+                                 List.nil(),
+                                 List.nil(), // thrown
+                                 body,
+                                 null);
+                 memberEnter.memberEnter(hashCode, env);
+                 tree.defs = tree.defs.append(hashCode);
+             }
+ 
+             if (requireEquals) {
+                 // public boolean equals(Object o) { throw new RuntimeException(message); }
+                 JCMethodDecl equals = make.
+                         MethodDef(make.Modifiers(Flags.PUBLIC | Flags.FINAL),
+                                 names.equals,
+                                 make.TypeIdent(TypeTag.BOOLEAN),
+                                 List.nil(),
+                                 List.of(make.VarDef(make.Modifiers(PARAMETER), names.fromString("o"), make.Ident(names.fromString("Object")), null )),
+                                 List.nil(), // thrown
+                                 body,
+                                 null);
+                 memberEnter.memberEnter(equals, env);
+                 tree.defs = tree.defs.append(equals);
+             }
+ 
+             if (requireToString) {
+                 // public String toString() { throw new RuntimeException(message); }
+                 JCMethodDecl toString = make.
+                         MethodDef(make.Modifiers(Flags.PUBLIC | Flags.FINAL),
+                                 names.toString,
+                                 make.Ident(names.fromString("String")),
+                                 List.nil(),
+                                 List.nil(),
+                                 List.nil(), // thrown
+                                 body,
+                                 null);
+                 memberEnter.memberEnter(toString, env);
+                 tree.defs = tree.defs.append(toString);
+             }
+ 
+         }
      }
  
  /* ***************************************************************************
   * tree building
   ****************************************************************************/