Re: [GIT pull] core/urgent for v5.4-rc7

[Linus Torvalds <torvalds@linux-foundation.org>]

On Sun, Nov 10, 2019 at 5:50 PM Joe Perches <joe@perches.com> wrote:
>
> The !! logical usage is not particularly common in the kernel.
> There seems to be only a couple/few dozen.

Your grep pattern is for the explicitly silly "turn a boolean to a
boolean". That should certainly be rare.

But I meant it in a more general way - there's a lot of common use of
"!!" for "turn this expression into a boolean". A trivial grep for
that (didn't check how correct it was - there might be comments that
are very excited too) implies that we have a fair amount of this
pattern:

    $ git grep '[^!]!![^!]' -- '*.[ch]' | wc -l
    7007

so the '!!' pattern itself isn't rare.

It's so common that the fact that people then occasionally get
confused and over-use it a bit in contexts where it's already boolean
isn't so surprising.

Personally, I still find that pattern non-intuitive, even when used
correctly. Double negatives aren't considered good in English, I don't
find it all that natural in C either.

But it's a pattern, it's idiomatic, and it's certainly not worth
forcing my own personal quirk on other people, so I won't accept
scripted patches to change it.

The one pattern I _really_ hate is the thing that some people are
taught to do: using "5 == x" instead of "x == 5" because it really
reads completely bogusly to me. Some people are taught that pattern
because it minimizes the risk of confusion between "==" and "=", and I
think that's completely wrong-headed.

Trying to teach people to write illegible code just to catch a syntax
error is crazy. You're "fixing" the wrong thing.

Oh well. We have a couple of those in the kernel too.  And I'm not
going to enforce my personal quirks there either, even if I'm
ClearlyRight(tm) and hold the OnlyCorrectOpinion(tm) in this matter.

                   Linus