Implicitly inherit from Object (#2559)

BREAKING CHANGE: Constant class ids of `String`, `ArrayBuffer` etc. moved one value up, with `Object` now represented by ID=0.

Author: dcodeIO

lib/loader/index.js

@@ -3,9 +3,9 @@ const ID_OFFSET = -8;
 const SIZE_OFFSET = -4;
 
 // Runtime ids
-const ARRAYBUFFER_ID = 0;
-const STRING_ID = 1;
-// const ARRAYBUFFERVIEW_ID = 2;
+// const OBJECT_ID = 0;
+const ARRAYBUFFER_ID = 1;
+const STRING_ID = 2;
 
 // Runtime type information
 const ARRAYBUFFERVIEW = 1 << 0;

lib/loader/tests/build/default.wasm

@@ -13,10 +13,10 @@ var loader = (function(exports) {
   // Runtime header offsets
   const ID_OFFSET = -8;
   const SIZE_OFFSET = -4; // Runtime ids
+  // const OBJECT_ID = 0;
 
-  const ARRAYBUFFER_ID = 0;
-  const STRING_ID = 1; // const ARRAYBUFFERVIEW_ID = 2;
-  // Runtime type information
+  const ARRAYBUFFER_ID = 1;
+  const STRING_ID = 2; // Runtime type information
 
   const ARRAYBUFFERVIEW = 1 << 0;
   const ARRAY = 1 << 1;

lib/loader/tests/build/legacy.wasm

@@ -1336,7 +1336,7 @@ function isPlainFunction(signature: Signature, mode: Mode): bool {
 
 function isPlainObject(clazz: Class): bool {
   // A plain object does not inherit and does not have a constructor or private properties
-  if (clazz.base) return false;
+  if (clazz.base && !clazz.prototype.implicitlyExtendsObject) return false;
   let members = clazz.members;
   if (members) {
     for (let _values = Map_values(members), i = 0, k = _values.length; i < k; ++i) {

lib/loader/umd/index.js

@@ -230,7 +230,7 @@ export class TSDBuilder extends ExportsWalker {
 
   isPlainObject(clazz: Class): bool {
     // A plain object does not inherit and does not have a constructor or private properties
-    if (clazz.base) return false;
+    if (clazz.base && !clazz.prototype.implicitlyExtendsObject) return false;
     let members = clazz.members;
     if (members) {
       for (let _values = Map_values(members), i = 0, k = _values.length; i < k; ++i) {

src/bindings/js.ts

@@ -732,6 +732,9 @@ export namespace BuiltinNames {
   export const String_eq = "~lib/string/String.__eq";
   export const String_ne = "~lib/string/String.__ne";
   export const String_not = "~lib/string/String.__not";
+
+  // std/object.ts
+  export const Object = "~lib/object/Object";
 }
 
 /** Builtin compilation context. */

src/bindings/tsd.ts

@@ -1716,7 +1716,7 @@ export class Compiler extends DiagnosticEmitter {
       }
 
       // check that super has been called if this is a derived class
-      if (classInstance.base && !flow.is(FlowFlags.CallsSuper)) {
+      if (classInstance.base && !classInstance.prototype.implicitlyExtendsObject && !flow.is(FlowFlags.CallsSuper)) {
         this.error(
           DiagnosticCode.Constructors_for_derived_classes_must_contain_a_super_call,
           instance.prototype.declaration.range
@@ -5950,7 +5950,7 @@ export class Compiler extends DiagnosticEmitter {
       assert(parent.kind == ElementKind.Class);
       let classInstance = <Class>parent;
       let baseClassInstance = classInstance.base;
-      if (!baseClassInstance) {
+      if (!baseClassInstance || classInstance.prototype.implicitlyExtendsObject) {
         this.error(
           DiagnosticCode._super_can_only_be_referenced_in_a_derived_class,
           expression.expression.range

src/builtins.ts

@@ -640,6 +640,14 @@ export class Program extends DiagnosticEmitter {
   }
   private _regexpInstance: Class | null = null;
 
+  /** Gets the standard `Object` prototype. */
+  get objectPrototype(): ClassPrototype {
+    let cached = this._objectPrototype;
+    if (!cached) this._objectPrototype = cached = <ClassPrototype>this.require(CommonNames.Object, ElementKind.ClassPrototype);
+    return cached;
+  }
+  private _objectPrototype: ClassPrototype | null = null;
+
   /** Gets the standard `Object` instance. */
   get objectInstance(): Class {
     let cached = this._objectInstance;
@@ -1257,10 +1265,11 @@ export class Program extends DiagnosticEmitter {
       }
     }
 
-    // register ArrayBuffer (id=0), String (id=1), ArrayBufferView (id=2)
-    assert(this.arrayBufferInstance.id == 0);
-    assert(this.stringInstance.id == 1);
-    assert(this.arrayBufferViewInstance.id == 2);
+    // register foundational classes with fixed ids
+    assert(this.objectInstance.id == 0);
+    assert(this.arrayBufferInstance.id == 1);
+    assert(this.stringInstance.id == 2);
+    assert(this.arrayBufferViewInstance.id == 3);
 
     // register classes backing basic types
     this.registerWrapperClass(Type.i8, CommonNames.I8);
@@ -2044,7 +2053,14 @@ export class Program extends DiagnosticEmitter {
     }
 
     // remember classes that extend another class
-    if (declaration.extendsType) queuedExtends.push(element);
+    if (declaration.extendsType) {
+      queuedExtends.push(element);
+    } else if (
+      !element.hasDecorator(DecoratorFlags.Unmanaged) &&
+      element.internalName != BuiltinNames.Object
+    ) {
+      element.implicitlyExtendsObject = true;
+    }
 
     // initialize members
     let memberDeclarations = declaration.members;
@@ -4165,6 +4181,8 @@ export class ClassPrototype extends DeclaredElement {
   instances: Map<string,Class> | null = null;
   /** Classes extending this class. */
   extendees: Set<ClassPrototype> = new Set();
+  /** Whether this class implicitly extends `Object`. */
+  implicitlyExtendsObject: bool = false;
 
   constructor(
     /** Simple name. */

src/compiler.ts

@@ -3121,6 +3121,10 @@ export class Resolver extends DiagnosticEmitter {
       // This is guaranteed to never happen at the entry of the recursion, i.e.
       // where `resolveClass` is called from other code.
       if (pendingClasses.has(base)) anyPending = true;
+
+    // Implicitly extend `Object` if a derived object
+    } else if (prototype.implicitlyExtendsObject) {
+      instance.setBase(this.program.objectInstance);
     }
 
     // Resolve interfaces if applicable
@@ -3298,13 +3302,15 @@ export class Resolver extends DiagnosticEmitter {
     let memoryOffset: u32 = 0;
     let base = instance.base;
     if (base) {
+      let implicitlyExtendsObject = instance.prototype.implicitlyExtendsObject;
       assert(!pendingClasses.has(base));
       let baseMembers = base.members;
       if (baseMembers) {
         // TODO: for (let [baseMemberName, baseMember] of baseMembers) {
         for (let _keys = Map_keys(baseMembers), i = 0, k = _keys.length; i < k; ++i) {
           let memberName = unchecked(_keys[i]);
           let baseMember = assert(baseMembers.get(memberName));
+          if (implicitlyExtendsObject && baseMember.is(CommonFlags.Static)) continue;
           let existingMember = instance.getMember(memberName);
           if (existingMember && !this.checkOverrideVisibility(memberName, existingMember, instance, baseMember, base, reportMode)) {
             continue; // keep previous