Re: snag of G_LIKELY()

[Daniel Elstner <daniel elstner gmx net>]

Am Sam, 2002-11-23 um 21.43 schrieb Mark Mielke:

> I think I missed the point... why shouldn't it be:

Yes :)

>   #define G_LIKELY(expr) __builtin_expect(!(expr), 0)
>   #define G_UNLIKELY(expr) __builtin_expect((expr), 0)

It has to be a double bang in this example because the logic would be
changed otherwise.  Remember, G_LIKELY() is used in an if() expression,
i.e. the return value of the expression matters.

But the real point of this discussion and my initial mail is that

    g_return_if_fail(a = b);

used to trigger a helpful GCC warning.  But since the introduction of
G_LIKELY() the warning isn't triggered anymore because the macro *has
to* add parentheses.

--Daniel