Bug 1484496: Part 4b - Add intrinsic type information to most nsSimpleEnumerators. r=froydnj

This allows JS callers to automatically get the correct types during
interation, without having to explicitly specify them.

Differential Revision: https://phabricator.services.mozilla.com/D3728

--HG--
extra : rebase_source : b708f382d8ea571d199c669bfed5b5a7ca9ffac4
extra : histedit_source : 7df6feb82088c8a5ca45dc28fe4d2b852c177fee

browser/components/dirprovider/DirectoryProvider.cpp

@@ -140,7 +140,7 @@ DirectoryProvider::GetFiles(const char *aKey, nsISimpleEnumerator* *aResult)
     nsCOMArray<nsIFile> distroFiles;
     AppendDistroSearchDirs(dirSvc, distroFiles);
 
-    return NS_NewArrayEnumerator(aResult, distroFiles);
+    return NS_NewArrayEnumerator(aResult, distroFiles, NS_GET_IID(nsIFile));
   }
 
   return NS_ERROR_FAILURE;

browser/components/migration/nsIEHistoryEnumerator.h

@@ -19,6 +19,11 @@ public:
 
   nsIEHistoryEnumerator();
 
+  const nsID& DefaultInterface() override
+  {
+    return NS_GET_IID(nsIWritablePropertyBag2);
+  }
+
 private:
   ~nsIEHistoryEnumerator() override;
 

docshell/base/nsDocShellEnumerator.h

@@ -46,6 +46,8 @@ public:
   // nsISimpleEnumerator
   NS_DECL_NSISIMPLEENUMERATOR
 
+  const nsID& DefaultInterface() override { return NS_GET_IID(nsIDocShell); }
+
 public:
   nsresult GetEnumerationRootItem(nsIDocShellTreeItem** aEnumerationRootItem);
   nsresult SetEnumerationRootItem(nsIDocShellTreeItem* aEnumerationRootItem);

dom/base/nsJSEnvironment.cpp

@@ -2938,7 +2938,13 @@ NS_IMETHODIMP nsJSArgArray::IndexOf(uint32_t startIndex, nsISupports *element, u
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
-NS_IMETHODIMP nsJSArgArray::Enumerate(nsISimpleEnumerator **_retval)
+NS_IMETHODIMP nsJSArgArray::ScriptedEnumerate(nsIJSIID* aElemIID, uint8_t aArgc,
+                                              nsISimpleEnumerator** aResult)
+{
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP nsJSArgArray::EnumerateImpl(const nsID& aEntryIID, nsISimpleEnumerator **_retval)
 {
   return NS_ERROR_NOT_IMPLEMENTED;
 }

dom/commandhandler/nsCommandGroup.cpp

@@ -23,6 +23,11 @@ public:
 
   NS_DECL_NSISIMPLEENUMERATOR
 
+  const nsID& DefaultInterface() override
+  {
+    return NS_GET_IID(nsISupportsCString);
+  }
+
 protected:
   ~nsGroupsEnumerator() override;
 
@@ -128,6 +133,11 @@ public:
 
   NS_DECL_NSISIMPLEENUMERATOR
 
+  const nsID& DefaultInterface() override
+  {
+    return NS_GET_IID(nsISupportsCString);
+  }
+
 protected:
   ~nsNamedGroupEnumerator() override;
 

dom/payments/PaymentRequestService.cpp

@@ -25,6 +25,12 @@ public:
   PaymentRequestEnumerator()
     : mIndex(0)
   {}
+
+  const nsID& DefaultInterface() override
+  {
+    return NS_GET_IID(nsIPaymentRequest);
+  }
+
 private:
   ~PaymentRequestEnumerator() override = default;
   uint32_t mIndex;

dom/plugins/base/nsPluginDirServiceProvider.cpp

@@ -62,7 +62,7 @@ nsPluginDirServiceProvider::GetPLIDDirectories(nsISimpleEnumerator **aEnumerator
   GetPLIDDirectoriesWithRootKey(nsIWindowsRegKey::ROOT_KEY_CURRENT_USER, dirs);
   GetPLIDDirectoriesWithRootKey(nsIWindowsRegKey::ROOT_KEY_LOCAL_MACHINE, dirs);
 
-  return NS_NewArrayEnumerator(aEnumerator, dirs);
+  return NS_NewArrayEnumerator(aEnumerator, dirs, NS_GET_IID(nsIFile));
 }
 
 nsresult

dom/workers/WorkerDebuggerManager.cpp

@@ -90,6 +90,11 @@ public:
 
   NS_DECL_NSISIMPLEENUMERATOR
 
+  const nsID& DefaultInterface() override
+  {
+    return NS_GET_IID(nsIWorkerDebugger);
+  }
+
 private:
   ~WorkerDebuggerEnumerator() override = default;
 };

extensions/cookie/nsPermissionManager.cpp

@@ -2611,7 +2611,7 @@ NS_IMETHODIMP nsPermissionManager::GetEnumerator(nsISimpleEnumerator **aEnum)
     }
   }
 
-  return NS_NewArrayEnumerator(aEnum, array);
+  return NS_NewArrayEnumerator(aEnum, array, NS_GET_IID(nsIPermission));
 }
 
 NS_IMETHODIMP nsPermissionManager::GetAllForURI(nsIURI* aURI, nsISimpleEnumerator **aEnum)
@@ -2660,7 +2660,7 @@ nsPermissionManager::GetAllForPrincipal(nsIPrincipal* aPrincipal,
     }
   }
 
-  return NS_NewArrayEnumerator(aEnum, array);
+  return NS_NewArrayEnumerator(aEnum, array, NS_GET_IID(nsIPermission));
 }
 
 NS_IMETHODIMP nsPermissionManager::Observe(nsISupports *aSubject, const char *aTopic, const char16_t *someData)

intl/strres/nsStringBundle.cpp

@@ -271,6 +271,11 @@ public:
     : mStringMap(aStringMap)
   {}
 
+  const nsID& DefaultInterface() override
+  {
+    return NS_GET_IID(nsIPropertyElement);
+  }
+
 protected:
   virtual ~StringMapEnumerator() = default;
 

js/xpconnect/src/XPCShellImpl.cpp

@@ -1513,7 +1513,7 @@ XPCShellDirProvider::GetFiles(const char* prop, nsISimpleEnumerator* *result)
         if (NS_SUCCEEDED(rv))
             dirs.AppendObject(file);
 
-        return NS_NewArrayEnumerator(result, dirs);
+        return NS_NewArrayEnumerator(result, dirs, NS_GET_IID(nsIFile));
     } else if (!strcmp(prop, NS_APP_PREFS_DEFAULTS_DIR_LIST)) {
         nsCOMArray<nsIFile> dirs;
         nsCOMPtr<nsIFile> appDir;
@@ -1524,7 +1524,7 @@ XPCShellDirProvider::GetFiles(const char* prop, nsISimpleEnumerator* *result)
             NS_SUCCEEDED(appDir->AppendNative(NS_LITERAL_CSTRING("preferences"))) &&
             NS_SUCCEEDED(appDir->Exists(&exists)) && exists) {
             dirs.AppendObject(appDir);
-            return NS_NewArrayEnumerator(result, dirs);
+            return NS_NewArrayEnumerator(result, dirs, NS_GET_IID(nsIFile));
         }
         return NS_ERROR_FAILURE;
     } else if (!strcmp(prop, NS_APP_PLUGINS_DIR_LIST)) {
@@ -1549,7 +1549,7 @@ XPCShellDirProvider::GetFiles(const char* prop, nsISimpleEnumerator* *result)
                 }
             }
         }
-        return NS_NewArrayEnumerator(result, dirs);
+        return NS_NewArrayEnumerator(result, dirs, NS_GET_IID(nsIFile));
     }
     return NS_ERROR_FAILURE;
 }

js/xpconnect/src/XPCWrappedJSClass.cpp

@@ -398,7 +398,7 @@ nsXPCWrappedJSClass::BuildPropertyEnumerator(XPCCallContext& ccx,
             return NS_ERROR_FAILURE;
     }
 
-    return NS_NewArrayEnumerator(aEnumerate, propertyArray);
+    return NS_NewArrayEnumerator(aEnumerate, propertyArray, NS_GET_IID(nsIProperty));
 }
 
 /***************************************************************************/

netwerk/base/nsLoadGroup.cpp

@@ -654,7 +654,7 @@ nsLoadGroup::GetRequests(nsISimpleEnumerator * *aRequests)
       requests.AppendObject(e->mKey);
     }
 
-    return NS_NewArrayEnumerator(aRequests, requests);
+    return NS_NewArrayEnumerator(aRequests, requests, NS_GET_IID(nsIRequest));
 }
 
 NS_IMETHODIMP

netwerk/cookie/nsCookieService.cpp

@@ -2493,7 +2493,7 @@ nsCookieService::GetEnumerator(nsISimpleEnumerator **aEnumerator)
     }
   }
 
-  return NS_NewArrayEnumerator(aEnumerator, cookieList);
+  return NS_NewArrayEnumerator(aEnumerator, cookieList, NS_GET_IID(nsICookie2));
 }
 
 NS_IMETHODIMP
@@ -2518,7 +2518,7 @@ nsCookieService::GetSessionEnumerator(nsISimpleEnumerator **aEnumerator)
     }
   }
 
-  return NS_NewArrayEnumerator(aEnumerator, cookieList);
+  return NS_NewArrayEnumerator(aEnumerator, cookieList, NS_GET_IID(nsICookie2));
 }
 
 static nsresult
@@ -4928,7 +4928,7 @@ nsCookieService::GetCookiesFromHost(const nsACString     &aHost,
     cookieList.AppendObject(cookies[i]);
   }
 
-  return NS_NewArrayEnumerator(aEnumerator, cookieList);
+  return NS_NewArrayEnumerator(aEnumerator, cookieList, NS_GET_IID(nsICookie2));
 }
 
 NS_IMETHODIMP
@@ -4987,7 +4987,7 @@ nsCookieService::GetCookiesWithOriginAttributes(
     }
   }
 
-  return NS_NewArrayEnumerator(aEnumerator, cookies);
+  return NS_NewArrayEnumerator(aEnumerator, cookies, NS_GET_IID(nsICookie2));
 }
 
 NS_IMETHODIMP

security/manager/ssl/PKCS11ModuleDB.cpp

@@ -192,7 +192,7 @@ PKCS11ModuleDB::ListModules(nsISimpleEnumerator** _retval)
     }
   }
 
-  return array->Enumerate(_retval);
+  return array->Enumerate(_retval, NS_GET_IID(nsIPKCS11Module));
 }
 
 NS_IMETHODIMP

security/manager/ssl/nsNSSCertificate.h

@@ -128,6 +128,8 @@ class nsNSSCertListEnumerator : public nsSimpleEnumerator
 public:
    NS_DECL_NSISIMPLEENUMERATOR
 
+   const nsID& DefaultInterface() override { return NS_GET_IID(nsIX509Cert); }
+
    explicit nsNSSCertListEnumerator(const mozilla::UniqueCERTCertList& certList);
 private:
    virtual ~nsNSSCertListEnumerator() {}

security/manager/ssl/nsPKCS11Slot.cpp

@@ -290,5 +290,5 @@ nsPKCS11Module::ListSlots(nsISimpleEnumerator** _retval)
     }
   }
 
-  return array->Enumerate(_retval);
+  return array->Enumerate(_retval, NS_GET_IID(nsIPKCS11Slot));
 }

security/manager/ssl/nsSiteSecurityService.cpp

@@ -473,7 +473,7 @@ SiteHPKPState::GetSha256Keys(nsISimpleEnumerator** aSha256Keys)
       return NS_ERROR_FAILURE;
     }
   }
-  return NS_NewArrayEnumerator(aSha256Keys, keys);
+  return NS_NewArrayEnumerator(aSha256Keys, keys, NS_GET_IID(nsIVariant));
 }
 
 NS_IMETHODIMP
@@ -1895,7 +1895,7 @@ nsSiteSecurityService::Enumerate(uint32_t aType,
     states.AppendObject(state);
   }
 
-  NS_NewArrayEnumerator(aEnumerator, states);
+  NS_NewArrayEnumerator(aEnumerator, states, NS_GET_IID(nsISiteSecurityState));
   return NS_OK;
 }
 

toolkit/profile/nsToolkitProfileService.cpp

@@ -149,6 +149,11 @@ private:
     public:
         NS_DECL_NSISIMPLEENUMERATOR
 
+        const nsID& DefaultInterface() override
+        {
+          return NS_GET_IID(nsIToolkitProfile);
+        }
+
         explicit ProfileEnumerator(nsToolkitProfile *first)
           { mCurrent = first; }
     private:

toolkit/xre/nsXREDirProvider.cpp

@@ -854,7 +854,7 @@ nsXREDirProvider::GetFilesInternal(const char* aProperty,
     LoadDirsIntoArray(mAppBundleDirectories,
                       kAppendNothing, directories);
 
-    rv = NS_NewArrayEnumerator(aResult, directories);
+    rv = NS_NewArrayEnumerator(aResult, directories, NS_GET_IID(nsIFile));
   }
   else if (!strcmp(aProperty, NS_APP_PREFS_DEFAULTS_DIR_LIST)) {
     nsCOMArray<nsIFile> directories;
@@ -863,7 +863,7 @@ nsXREDirProvider::GetFilesInternal(const char* aProperty,
     LoadDirsIntoArray(mAppBundleDirectories,
                       kAppendPrefDir, directories);
 
-    rv = NS_NewArrayEnumerator(aResult, directories);
+    rv = NS_NewArrayEnumerator(aResult, directories, NS_GET_IID(nsIFile));
   }
   else if (!strcmp(aProperty, NS_APP_CHROME_DIR_LIST)) {
     // NS_APP_CHROME_DIR_LIST is only used to get default (native) icons
@@ -878,7 +878,7 @@ nsXREDirProvider::GetFilesInternal(const char* aProperty,
                       kAppendChromeDir,
                       directories);
 
-    rv = NS_NewArrayEnumerator(aResult, directories);
+    rv = NS_NewArrayEnumerator(aResult, directories, NS_GET_IID(nsIFile));
   }
   else if (!strcmp(aProperty, NS_APP_PLUGINS_DIR_LIST)) {
     nsCOMArray<nsIFile> directories;
@@ -908,7 +908,7 @@ nsXREDirProvider::GetFilesInternal(const char* aProperty,
                         directories);
     }
 
-    rv = NS_NewArrayEnumerator(aResult, directories);
+    rv = NS_NewArrayEnumerator(aResult, directories, NS_GET_IID(nsIFile));
     NS_ENSURE_SUCCESS(rv, rv);
 
     rv = NS_SUCCESS_AGGREGATE_RESULT;

uriloader/exthandler/HandlerService.js

@@ -217,7 +217,7 @@ HandlerService.prototype = {
       );
       handlers.appendElement(handler);
     }
-    return handlers.enumerate();
+    return handlers.enumerate(Ci.nsIHandlerInfo);
   },
 
   // nsIHandlerService

uriloader/exthandler/win/nsMIMEInfoWin.cpp

@@ -167,7 +167,7 @@ nsMIMEInfoWin::GetEnumerator(nsISimpleEnumerator* *_retval)
   if (variant)
     properties.AppendObject(variant);
 
-  return NS_NewArrayEnumerator(_retval, properties);
+  return NS_NewArrayEnumerator(_retval, properties, NS_GET_IID(nsIVariant));
 }
 
 static nsresult GetIconURLVariant(nsIFile* aApplication, nsIVariant* *_retval)

widget/gtk/nsFilePicker.cpp

@@ -346,7 +346,7 @@ nsFilePicker::GetFiles(nsISimpleEnumerator **aFiles)
   NS_ENSURE_ARG_POINTER(aFiles);
 
   if (mMode == nsIFilePicker::modeOpenMultiple) {
-    return NS_NewArrayEnumerator(aFiles, mFiles);
+    return NS_NewArrayEnumerator(aFiles, mFiles, NS_GET_IID(nsIFile));
   }
 
   return NS_ERROR_FAILURE;

widget/nsBaseFilePicker.cpp

@@ -112,6 +112,8 @@ public:
     , mMode(aMode)
   {}
 
+  const nsID& DefaultInterface() override { return NS_GET_IID(nsIFile); }
+
   NS_IMETHOD
   GetNext(nsISupports** aResult) override
   {
@@ -283,7 +285,7 @@ NS_IMETHODIMP nsBaseFilePicker::GetFiles(nsISimpleEnumerator **aFiles)
 
   files.AppendObject(file);
 
-  return NS_NewArrayEnumerator(aFiles, files);
+  return NS_NewArrayEnumerator(aFiles, files, NS_GET_IID(nsIFile));
 }
 
 // Set the display directory

widget/windows/nsFilePicker.cpp

@@ -688,7 +688,7 @@ NS_IMETHODIMP
 nsFilePicker::GetFiles(nsISimpleEnumerator **aFiles)
 {
   NS_ENSURE_ARG_POINTER(aFiles);
-  return NS_NewArrayEnumerator(aFiles, mFiles);
+  return NS_NewArrayEnumerator(aFiles, mFiles, NS_GET_IID(nsIFile));
 }
 
 // Get the file + path

xpcom/components/nsCategoryManager.cpp

@@ -59,6 +59,11 @@ public:
   NS_DECL_NSISIMPLEENUMERATOR
   NS_DECL_NSIUTF8STRINGENUMERATOR
 
+  const nsID& DefaultInterface() override
+  {
+    return NS_GET_IID(nsISupportsCString);
+  }
+
 protected:
   // Callback function for NS_QuickSort to sort mArray
   static int SortCallback(const void*, const void*, void*);

xpcom/ds/nsArray.cpp

@@ -7,6 +7,7 @@
 #include "nsArray.h"
 #include "nsArrayEnumerator.h"
 #include "nsThreadUtils.h"
+#include "xpcjsid.h"
 
 NS_INTERFACE_MAP_BEGIN(nsArray)
   NS_INTERFACE_MAP_ENTRY(nsIArray)
@@ -79,11 +80,22 @@ nsArrayBase::IndexOf(uint32_t aStartIndex, nsISupports* aElement,
 }
 
 NS_IMETHODIMP
-nsArrayBase::Enumerate(nsISimpleEnumerator** aResult)
+nsArrayBase::ScriptedEnumerate(nsIJSIID* aElemIID, uint8_t aArgc,
+                               nsISimpleEnumerator** aResult)
 {
+  if (aArgc > 0 && aElemIID) {
+    return NS_NewArrayEnumerator(aResult, static_cast<nsIArray*>(this), *aElemIID->GetID());
+  }
   return NS_NewArrayEnumerator(aResult, static_cast<nsIArray*>(this));
 }
 
+
+NS_IMETHODIMP
+nsArrayBase::EnumerateImpl(const nsID& aElemIID, nsISimpleEnumerator** aResult)
+{
+  return NS_NewArrayEnumerator(aResult, static_cast<nsIArray*>(this), aElemIID);
+}
+
 // nsIMutableArray implementation
 
 NS_IMETHODIMP

xpcom/ds/nsArrayEnumerator.cpp

@@ -23,17 +23,21 @@ public:
   NS_DECL_NSISIMPLEENUMERATOR
 
   // nsSimpleArrayEnumerator methods
-  explicit nsSimpleArrayEnumerator(nsIArray* aValueArray)
+  explicit nsSimpleArrayEnumerator(nsIArray* aValueArray, const nsID& aEntryIID)
     : mValueArray(aValueArray)
+    , mEntryIID(aEntryIID)
     , mIndex(0)
   {
   }
 
+  const nsID& DefaultInterface() override { return mEntryIID; }
+
 private:
   ~nsSimpleArrayEnumerator() override = default;
 
 protected:
   nsCOMPtr<nsIArray> mValueArray;
+  const nsID mEntryIID;
   uint32_t mIndex;
 };
 
@@ -86,9 +90,10 @@ nsSimpleArrayEnumerator::GetNext(nsISupports** aResult)
 }
 
 nsresult
-NS_NewArrayEnumerator(nsISimpleEnumerator** aResult, nsIArray* aArray)
+NS_NewArrayEnumerator(nsISimpleEnumerator** aResult, nsIArray* aArray,
+                      const nsID& aEntryIID)
 {
-  RefPtr<nsSimpleArrayEnumerator> enumer = new nsSimpleArrayEnumerator(aArray);
+  RefPtr<nsSimpleArrayEnumerator> enumer = new nsSimpleArrayEnumerator(aArray, aEntryIID);
   enumer.forget(aResult);
   return NS_OK;
 }
@@ -106,16 +111,19 @@ public:
   NS_DECL_NSISIMPLEENUMERATOR
 
   // Use this instead of `new`.
-  static nsCOMArrayEnumerator* Allocate(const nsCOMArray_base& aArray);
+  static nsCOMArrayEnumerator* Allocate(const nsCOMArray_base& aArray, const nsID& aEntryIID);
 
   // specialized operator to make sure we make room for mValues
   void operator delete(void* aPtr) { free(aPtr); }
 
+  const nsID& DefaultInterface() override { return mEntryIID; }
+
 private:
   // nsSimpleArrayEnumerator methods
-  nsCOMArrayEnumerator()
+  explicit nsCOMArrayEnumerator(const nsID& aEntryIID)
     : mIndex(0)
     , mArraySize(0)
+    , mEntryIID(aEntryIID)
   {
     mValueArray[0] = nullptr;
   }
@@ -126,6 +134,8 @@ protected:
   uint32_t mIndex;            // current position
   uint32_t mArraySize;        // size of the array
 
+  const nsID& mEntryIID;
+
   // this is actually bigger
   nsISupports* mValueArray[1];
 };
@@ -175,7 +185,7 @@ nsCOMArrayEnumerator::GetNext(nsISupports** aResult)
 }
 
 nsCOMArrayEnumerator*
-nsCOMArrayEnumerator::Allocate(const nsCOMArray_base& aArray)
+nsCOMArrayEnumerator::Allocate(const nsCOMArray_base& aArray, const nsID& aEntryIID)
 {
   // create enough space such that mValueArray points to a large
   // enough value. Note that the initial value of aSize gives us
@@ -191,7 +201,7 @@ nsCOMArrayEnumerator::Allocate(const nsCOMArray_base& aArray)
 
   // Allocate a buffer large enough to contain our object and its array.
   void* mem = moz_xmalloc(size);
-  auto result = new (mozilla::KnownNotNull, mem) nsCOMArrayEnumerator();
+  auto result = new (mozilla::KnownNotNull, mem) nsCOMArrayEnumerator(aEntryIID);
 
   result->mArraySize = count;
 
@@ -209,9 +219,10 @@ nsCOMArrayEnumerator::Allocate(const nsCOMArray_base& aArray)
 
 nsresult
 NS_NewArrayEnumerator(nsISimpleEnumerator** aResult,
-                      const nsCOMArray_base& aArray)
+                      const nsCOMArray_base& aArray,
+                      const nsID& aEntryIID)
 {
-  RefPtr<nsCOMArrayEnumerator> enumerator = nsCOMArrayEnumerator::Allocate(aArray);
+  RefPtr<nsCOMArrayEnumerator> enumerator = nsCOMArrayEnumerator::Allocate(aArray, aEntryIID);
   enumerator.forget(aResult);
   return NS_OK;
 }

xpcom/ds/nsArrayEnumerator.h

@@ -9,7 +9,7 @@
 
 // enumerator implementation for nsIArray
 
-#include "nscore.h"
+#include "nsISupports.h"
 
 class nsISimpleEnumerator;
 class nsIArray;
@@ -19,7 +19,8 @@ class nsCOMArray_base;
 // The enumerator holds an owning reference to the array.
 nsresult
 NS_NewArrayEnumerator(nsISimpleEnumerator** aResult,
-                      nsIArray* aArray);
+                      nsIArray* aArray,
+                      const nsID& aEntryIID = NS_GET_IID(nsISupports));
 
 // create an enumerator for an existing nsCOMArray<T> implementation
 // The enumerator will hold an owning reference to each ELEMENT in
@@ -27,6 +28,7 @@ NS_NewArrayEnumerator(nsISimpleEnumerator** aResult,
 // without its objects going away.
 nsresult
 NS_NewArrayEnumerator(nsISimpleEnumerator** aResult,
-                      const nsCOMArray_base& aArray);
+                      const nsCOMArray_base& aArray,
+                      const nsID& aEntryIID = NS_GET_IID(nsISupports));
 
 #endif

xpcom/ds/nsHashPropertyBag.cpp

@@ -120,7 +120,8 @@ nsHashPropertyBagBase::GetEnumerator(nsISimpleEnumerator** aResult)
     propertyArray->AppendElement(sprop);
   }
 
-  return NS_NewArrayEnumerator(aResult, propertyArray);
+  return NS_NewArrayEnumerator(aResult, propertyArray,
+                               NS_GET_IID(nsIProperty));
 }
 
 #define IMPL_GETSETPROPERTY_AS(Name, Type) \

xpcom/ds/nsIArray.idl

@@ -5,6 +5,7 @@
 
 #include "nsISupports.idl"
 
+interface nsIJSIID;
 interface nsISimpleEnumerator;
 
 /**
@@ -31,7 +32,7 @@ interface nsISimpleEnumerator;
  * null is a valid entry in the array, and as such any nsISupports
  * parameters may be null, except where noted.
  */
-[scriptable, uuid(114744d9-c369-456e-b55a-52fe52880d2d)]
+[scriptable, builtinclass, uuid(114744d9-c369-456e-b55a-52fe52880d2d)]
 interface nsIArray : nsISupports
 {
     /**
@@ -87,5 +88,17 @@ interface nsIArray : nsISupports
      * @throws NS_ERROR_FAILURE if the array is empty (to make it easy
      *         to detect errors), or NS_ERROR_OUT_OF_MEMORY if out of memory.
      */
-    nsISimpleEnumerator enumerate();
+    [binaryname(ScriptedEnumerate), optional_argc]
+    nsISimpleEnumerator enumerate([optional] in nsIJSIID aElemIID);
+
+    [noscript]
+    nsISimpleEnumerator enumerateImpl(in nsIDRef aElemIID);
+
+    %{C++
+    nsresult
+    Enumerate(nsISimpleEnumerator** aRetVal, const nsID& aElemIID = NS_GET_IID(nsISupports))
+    {
+      return EnumerateImpl(aElemIID, aRetVal);
+    }
+    %}
 };

xpcom/ds/nsIArrayExtensions.idl

@@ -24,7 +24,7 @@
  * itself, possibly getting rid of the Count() method, as it duplicates
  * nsIArray functionality.
  */
-[scriptable, uuid(261d442e-050c-453d-8aaa-b3f23bcc528b)]
+[scriptable, builtinclass, uuid(261d442e-050c-453d-8aaa-b3f23bcc528b)]
 interface nsIArrayExtensions : nsIArray
 {
   /**

xpcom/ds/nsIMutableArray.idl

@@ -20,7 +20,7 @@
  * Any of these methods may throw NS_ERROR_OUT_OF_MEMORY when the
  * array must grow to complete the call, but the allocation fails.
  */
-[scriptable, uuid(af059da0-c85b-40ec-af07-ae4bfdc192cc)]
+[scriptable, builtinclass, uuid(af059da0-c85b-40ec-af07-ae4bfdc192cc)]
 interface nsIMutableArray : nsIArrayExtensions
 {
     /**

xpcom/ds/nsISimpleEnumerator.idl

@@ -31,7 +31,8 @@ interface nsIJSEnumerator : nsISupports {
 interface nsISimpleEnumeratorBase : nsISupports {
   /**
    * Returns a JavaScript iterator for all remaining entries in the enumerator.
-   * Each entry is queried only to nsISupports.
+   * Each entry is typically queried to the appropriate interface for the
+   * enumerator.
    */
   [symbol]
   nsIJSEnumerator iterator();

xpcom/ds/nsObserverList.h

@@ -82,6 +82,8 @@ public:
 
   explicit nsObserverEnumerator(nsObserverList* aObserverList);
 
+  const nsID& DefaultInterface() override { return NS_GET_IID(nsIObserver); }
+
 private:
   ~nsObserverEnumerator() override = default;
 

xpcom/ds/nsPersistentProperties.cpp

@@ -570,7 +570,7 @@ nsPersistentProperties::Enumerate(nsISimpleEnumerator** aResult)
     }
   }
 
-  return NS_NewArrayEnumerator(aResult, props);
+  return NS_NewArrayEnumerator(aResult, props, NS_GET_IID(nsIPropertyElement));
 }
 
 ////////////////////////////////////////////////////////////////////////////////

xpcom/ds/nsSimpleEnumerator.cpp

@@ -71,7 +71,7 @@ NS_IMPL_ISUPPORTS(JSEnumerator, nsIJSEnumerator)
 nsresult
 nsSimpleEnumerator::Iterator(nsIJSEnumerator **aResult)
 {
-  auto result = MakeRefPtr<JSEnumerator>(this, NS_GET_IID(nsISupports));
+  auto result = MakeRefPtr<JSEnumerator>(this, DefaultInterface());
   result.forget(aResult);
   return NS_OK;
 }

xpcom/ds/nsSimpleEnumerator.h

@@ -14,6 +14,8 @@ class nsSimpleEnumerator : public nsISimpleEnumerator
   NS_DECL_ISUPPORTS
   NS_DECL_NSISIMPLEENUMERATORBASE
 
+  virtual const nsID& DefaultInterface() { return NS_GET_IID(nsISupports); }
+
 protected:
   virtual ~nsSimpleEnumerator() = default;
 };

xpcom/ds/nsStringEnumerator.cpp

@@ -59,6 +59,14 @@ public:
   NS_IMETHOD GetNext(nsAString& aResult) override;
   NS_DECL_NSISIMPLEENUMERATOR
 
+  const nsID& DefaultInterface() override
+  {
+    if (mIsUnicode) {
+      return NS_GET_IID(nsISupportsString);
+    }
+    return NS_GET_IID(nsISupportsCString);
+  }
+
 private:
   ~nsStringEnumerator()
   {

xpcom/io/nsAppFileLocationProvider.cpp

@@ -390,6 +390,8 @@ public:
   {
   }
 
+  const nsID& DefaultInterface() override { return NS_GET_IID(nsIFile); }
+
   NS_IMETHOD HasMoreElements(bool* aResult) override
   {
     while (!mNext && *mCurrentKey) {

xpcom/io/nsLocalFileUnix.cpp

@@ -110,6 +110,8 @@ public:
 
   NS_FORWARD_NSISIMPLEENUMERATORBASE(nsSimpleEnumerator::)
 
+  const nsID& DefaultInterface() override { return NS_GET_IID(nsIFile); }
+
 private:
   ~nsDirEnumeratorUnix() override;
 

xpcom/io/nsLocalFileWin.cpp

@@ -241,6 +241,8 @@ public:
   NS_FORWARD_NSISIMPLEENUMERATORBASE(nsSimpleEnumerator::)
   nsresult Init();
 
+  const nsID& DefaultInterface() override { return NS_GET_IID(nsIFile); }
+
   NS_IMETHOD GetNextFile(nsIFile** aResult) override
   {
     bool hasMore = false;
@@ -701,6 +703,8 @@ public:
   {
   }
 
+  const nsID& DefaultInterface() override { return NS_GET_IID(nsIFile); }
+
   nsresult Init(nsIFile* aParent)
   {
     nsAutoString filepath;

xpfe/appshell/nsAppShellWindowEnumerator.h

@@ -83,6 +83,8 @@ public:
                           nsWindowMediator& inMediator);
   virtual ~nsASXULWindowEnumerator();
   NS_IMETHOD GetNext(nsISupports **retval) override;
+
+  const nsID& DefaultInterface() override { return NS_GET_IID(nsIXULWindow); }
 };
 
 //