Bug 231954 – clang-tidy checker to find places where WTFMove/std::move are missing with RetainPtr<>

• Component: Tools / Tests
• Status: NEW

[David Kilzer (:ddkilzer)]

clang-tidy checker to find places where WTFMove/std::move are missing with RetainPtr<>.

In Bug 231814 Comment #6 and Bug 231814 Comment #11, I reimplemented a suggestion from Darin, but I missed adding a WTFMove() of a RetainPtr<> object that was going out of scope, resulting in some ref count churn:

    RetainPtr<SecKeyRef> LocalConnection::createCredentialPrivateKey(...)
    {
        RetainPtr privateKeyAttributes = @{ ... };

        if (context) {
            auto mutableCopy = adoptNS([privateKeyAttributes mutableCopy]);
            mutableCopy.get()[(id)kSecUseAuthenticationContext] = context;
            privateKeyAttributes = mutableCopy;  // FIXME: Missing WTFMove(mutableCopy)
        }
        [...]
    }

A clang-tidy checker would be useful that warns about a missing WTFMove/std::move where a RetainPtr<> object is last referenced in a block/function using an assignment operator to another RetainPtr<> variable.

I'm sure there are more of these cases in WebKit, and such a checker could probably be made generic enough for any class with an operator=(&&) implementation.

[Radar WebKit Bug Importer]

<rdar://problem/84664132>