Synchronized return objective-c

Question

- (id)methodThatReturnsSomething
{
    @synchronized(self) {
        return nil;
    }
}

When I do this on Xcode, it returns me a warning: "Control reaches end of non-void function"

Is there any problem with that code?

Answer 1

I don't understand what you want to do in your code, but

- (id)methodThatReturnsSomething
{
    @synchronized(self) {
    }
    return nil;
}

should have the same effect (postponing the return until the lock associated to self is freed), without the compiler warning.

But: what did you want to do? You don't have to put a @synchronized in this manner.

Answer 2

Yes,

The @synchronized block is similar to doing this (my terrible pseudocode)

- (id)methodThatReturnsSomething
{
    if ([self notlocked]) {
        [self lock]
        return nil;
        [self unlock]
    }
}

You can see that if another function call is made, then it will reach the last } without returning something.

Answer 3

The synchronization in the code as posted is redundant but there is no problem with it as such:
@synchronized blocks are either exited normally or through exceptions. As you already have a return statement in it, another statement after the block is not needed.

Answer 4

It barfs up a compiler warning because of a bug in some versions of the compiler that are fixed in other / later versions of the compiler.

In this case, yes, you really did stumble upon a compiler bug.