Fix is_object on resources

PHP certainly never runs out of fun surprises to spring on me!

hphp/runtime/base/builtin_functions.h

@@ -268,14 +268,14 @@ bool isset(CArrRef v, CObjRef offset);
 bool isset(CArrRef v, CVarRef offset);
 bool isset(CArrRef v, CStrRef offset, bool isString = false);
 
-inline Variant unset(Variant &v)               { v.unset();   return uninit_null();}
-inline Variant unset(CVarRef v)                {              return uninit_null();}
-inline Variant setNull(Variant &v)             { v.setNull(); return uninit_null();}
-inline Object setNull(Object &v)               { v.reset();   return Object();}
-inline Array setNull(Array &v)                 { v.reset();   return Array();}
-inline String setNull(String &v)               { v.reset();   return String();}
-inline Variant unset(Object &v)                { v.reset();   return uninit_null();}
-inline Variant unset(Array &v)                 { v.reset();   return uninit_null();}
+inline Variant unset(Variant &v)   { v.unset();   return uninit_null();}
+inline Variant unset(CVarRef v)    {              return uninit_null();}
+inline Variant setNull(Variant &v) { v.setNull(); return uninit_null();}
+inline Object setNull(Object &v)   { v.reset();   return Object();}
+inline Array setNull(Array &v)     { v.reset();   return Array();}
+inline String setNull(String &v)   { v.reset();   return String();}
+inline Variant unset(Object &v)    { v.reset();   return uninit_null();}
+inline Variant unset(Array &v)     { v.reset();   return uninit_null();}
 
 ///////////////////////////////////////////////////////////////////////////////
 // type testing
@@ -287,7 +287,11 @@ inline bool is_double(CVarRef v) { return v.is(KindOfDouble);}
 inline bool is_string(CVarRef v) { return v.isString();}
 inline bool is_array(CVarRef v)  { return v.is(KindOfArray);}
 inline bool is_object(CVarRef var) {
-  return var.is(KindOfObject) && !var.isResource();
+  // NB: just doing !var.isResource() is not right. isResource can have custom
+  // implementations in extension classes, and even if that returns false,
+  // is_object is still supposed to return false. Because PHP.
+  return var.is(KindOfObject) &&
+    var.getObjectData()->getVMClass() != SystemLib::s_resourceClass;
 }
 inline bool is_empty_string(CVarRef v) {
   return v.isString() && v.getStringData()->empty();

hphp/runtime/base/object_data.h

@@ -142,7 +142,7 @@ class ObjectData : public CountableNF {
   CStrRef o_getClassName() const;
   CStrRef o_getParentName() const;
   virtual CStrRef o_getClassNameHook() const;
-  virtual bool isResource() const { return false;}
+  virtual bool isResource() const { return false; }
   int o_getId() const { return o_id;}
 
   // overridable casting

hphp/test/quick/not_a_resource.php

@@ -0,0 +1,15 @@
+<?php
+// Copyright 2004-present Facebook. All Rights Reserved.
+
+function r($a) {
+  var_dump(is_resource($a));
+  var_dump(is_object($a));
+  var_dump($a);
+}
+
+$f = imagecreate(10, 10);
+r($f);
+imagedestroy($f);
+// Now it's not a resource anymore! It's not an object either. What is it?
+// It's PHP, that's what.
+r($f);

hphp/test/quick/not_a_resource.php.expect

@@ -0,0 +1,6 @@
+bool(true)
+bool(false)
+resource(4) of type (gd)
+bool(false)
+bool(false)
+resource(4) of type (__resource)