Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Thu,  6 May 2021 22:09:07 -0700
Message-Id: <20210507050908.1008686-1-davidgow@google.com>
Mime-Version: 1.0
Subject: [PATCH 1/2] kunit: Do not typecheck binary assertions
From:   David Gow <davidgow@google.com>
To:     Brendan Higgins <brendanhiggins@google.com>,
        Daniel Latypov <dlatypov@google.com>,
        Shuah Khan <skhan@linuxfoundation.org>
Cc:     David Gow <davidgow@google.com>, kunit-dev@googlegroups.com,
        linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

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.

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@google.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.

Cheers,
-- David

 include/kunit/test.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/include/kunit/test.h b/include/kunit/test.h
index 49601c4b98b8..4c56ffcb7403 100644
--- a/include/kunit/test.h
+++ b/include/kunit/test.h
@@ -775,7 +775,6 @@ void kunit_do_assertion(struct kunit *test,
 do {									       \
 	typeof(left) __left = (left);					       \
 	typeof(right) __right = (right);				       \
-	((void)__typecheck(__left, __right));				       \
 									       \
 	KUNIT_ASSERTION(test,						       \
 			__left op __right,				       \
-- 
2.31.1.607.g51e8a6a459-goog