linux-kernel - Re: [PATCH 1/2] kunit: Do not typecheck binary assertions

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Date:   Sat, 8 May 2021 13:56:52 +0800
From:   David Gow <davidgow@...gle.com>
To:     Brendan Higgins <brendanhiggins@...gle.com>
Cc:     Daniel Latypov <dlatypov@...gle.com>,
        Shuah Khan <skhan@...uxfoundation.org>,
        KUnit Development <kunit-dev@...glegroups.com>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] kunit: Do not typecheck binary assertions

On Sat, May 8, 2021 at 4:05 AM 'Brendan Higgins' via KUnit Development
<kunit-dev@...glegroups.com> wrote:
>
> On Thu, May 6, 2021 at 10:09 PM David Gow <davidgow@...gle.com> wrote:
> >
> > The use of typecheck() in KUNIT_EXPECT_EQ() and friends is causing more
> > problems than I think it's worth. Things like enums need to have their
> > values explicitly cast, and literals all need to be very precisely typed
> > for the code to compile.
>
> nit: I have not had the typecheck() call prevent any code from
> compiling, just generating warnings. I guess you can have a build set
> to cause any warning to be promoted to an error; still, I think this
> statement is misleading.
>

Whoops -- it was the issue in patch 2 that was causing the error. This
is indeed just a warning.

I'll send out a second version with a more accurate description next
week, assuming no further issues appear.

> > While typechecking does have its uses, the additional overhead of having
> > lots of needless casts -- combined with the awkward error messages which
> > don't mention which types are involved -- makes tests less readable and
> > more difficult to write.
> >
> > By removing the typecheck() call, the two arguments still need to be of
> > compatible types, but don't need to be of exactly the same time, which
> > seems a less confusing and more useful compromise.
> >
> > Signed-off-by: David Gow <davidgow@...gle.com>
>
> Looks good to me.
>
> Reviewed-by: Brendan Higgins <brendanhiggins@...gle.com>
>
> > ---
> >
> > I appreciate that this is probably a bit controversial (and, indeed, I
> > was a bit hesitant about sending it out myself), but after sitting on it
> > for a few days, I still think this is probably an improvement overall.
> >
> > The second patch does fix what I think is an actual bug, though, so even
> > if this isn't determined to be a good idea, it (or some equivalent)
> > should probably go through.
>
> I don't remember being a huge fan of the typecheck when it was asked
> for either. I think I am a little bit more indifferent than you;
> nevertheless, I support this change.
>
> --
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