I have made changes to already_AddRefed (Bug 967364) and getter_AddRefs (Bug 345123) to eliminate some potential mistakes that can be made with them.
For already_AddRefed: - already_AddRefed::get() has been renamed to already_AddRefed::take(), to make the transfer of ownership of the pointer in question more explicit. - already_AddRefed::take() and assigning an already_AddRefed to a nsCOMPtr/nsRefPtr consume the value of the already_AddRefed. That is, the mRawPtr is set to nullptr after performing one of these actions. - already_AddRefed's destructor fatally asserts that the mRawPtr is now null. This means you are now required to transfer an already_AddRefed to a smart pointer or to call take() on it. - on compilers that support it, take() warns if the result is unused. A shorthand has been introduced with mozilla::unused to allow "throwing away" the pointer by directing an already_AddRefed into unused. - because take() respects const-ness, already_AddRefed must now be passed by reference in certain situations (e.g. when it is an r-value). These changes are intended to make ownership transfer semantics clearer and to make it harder to unintentionally leak a pointer from an already_AddRefed. For getter_AddRefs: - The operator nsISupports** has been removed. Previously, getter_AddRefs's operator nsISupports** would allow you to write the following code: nsresult Foo(nsISupports** aOutparam); nsCOMPtr<nsIFoo> foo; Foo(getter_AddRefs(foo)); This is a very dangerous cast, as Foo only promises to return an nsISupports*, not an nsIFoo*. Now that the operator nsISupports** has been removed, this code must be written as: nsresult Foo(nsISupports** aOutparam); nsCOMPtr<nsISupports> supports; Foo(getter_AddRefs(supports)); nsCOMPtr<nsIFoo> foo = do_QueryInterface(supports). Most of the code I saw in the tree that needed to change was using nsISimpleEnumerator or nsIObjectInputStream. Let me know if you have any questions. - Kyle _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
