On Tue, Jul 23, 2024 at 05:03:39PM -0400, Jeff King wrote:

On Mon, Jul 22, 2024 at 11:02:24AM +0200, Patrick Steinhardt wrote:

quoted

quoted

I'd noticed it, too, while doing recent leak fixes. But since Patrick
has been working on leaks and is the go-to person for reftables, I
assumed he had already seen it and there was something clever going on. ;)

Nah, you assumed too much :) I just forgot to mark this as leak-free and
the topic crossed with my memory-leak-fix topics, so I didn't yet find
the time to fix it.

Ah, OK. :) Then I think we did the right thing in your absence.

:)

quoted

It does highlight an issue though: I think memory leak checks should be
opt-out rather than opt-in by now. Most of our tests run just fine with
the memory leak checker enabled, and that's also where we want to be
headed. So making tests opt-out would likely raise more eyebrows when
new tests are being added that explicitly opt out.

The only reason I didn't send a patch like this yet is that it would of
course create quite a bit of churn in our tests. I'm not sure whether
that churn is really worth it, or whether we should instead just
continue fixing tests until we can get rid of this marking altogether
because all of our tests pass.

I could see arguments in both directions. I'd worry that by switching
the default to "assume leak free", it may end up with misalignment
between who introduces the bug and who deals with the fallout.

Right now, if I introduce a test that is leak free but don't mark it,
somebody working on leaks later runs in check mode and says "yay, it
passes. Let's mark it". It becomes their task to do, but it's an
easy-ish task.

If we go the other way, then a new test that _does_ leak means that
either:

  1. The original author notices the CI leaks job failing.

     a. They introduced the leak, and it was caught early. Yay!

     b. The leak is in some random part of Git that their test happened
	to trigger. Now they spend effort proving it was not their fault
	before they annotate the test with "does not pass leak".

  2. The original author does not notice. Somebody notices later when
     doing leak-checking (or I guess just running their own CI, if we
     are hitting these by default). Now they are stuck with doing (1a)
     or (1b) themselves, even though they do not care about the original
     topic.

So I dunno. If we think people are paying attention to CI on their
topics, and we think that we are close enough to leak-free that (1b)
won't come up a lot, it might make sense. I'm not quite sure we're there
yet on the latter, but it's mostly gut feeling (and I know things have
gotten a bit better recently, too).

I don't know either.  Maybe it seems a bit early still considering the
numbers we have: 

   $ git grep -l PASSES_SANITIZE_LEAK=true t/t[0-9][0-9][0-9][0-9]-*.sh | wc -l
   678
   $ git grep -L PASSES_SANITIZE_LEAK=true t/t[0-9][0-9][0-9][0-9]-*.sh | wc -l
   329

BTW, perhaps we want to do this:

----- >8 --------- >8 --------- >8 --------- >8 ----
Subject: [PATCH] t: do not mark tests as no-leak-free

The mark TEST_PASSES_SANITIZE_LEAK=false and the absence of it mean the
same thing: the test triggers leaks.  However, explicitly declaring that
the test leak, with TEST_PASSES_SANITIZE_LEAK=false, can suggest there
is some special consideration for it, which is not the case.

Looking back at the history of the tests we're modifying in this patch,
we see that both were marked as "leak-free", but later started
triggering leaks and had to be re-marked accordingly as "no-leak-free".
Instead of removing the mark entirely, it was changed to "false".

It doesn't seem to have much historical value to keep the mark for this
reason, and removing it reduces the confusion that it has some special
meaning.

Do it so.

Signed-off-by: Rubén Justo <redacted>
---
 t/t0210-trace2-normal.sh | 1 -
 t/t0211-trace2-perf.sh   | 1 -
 2 files changed, 2 deletions(-)

diff --git a/t/t0210-trace2-normal.sh b/t/t0210-trace2-normal.sh
index c312657a12..eff9a59dbd 100755
--- a/t/t0210-trace2-normal.sh
+++ b/t/t0210-trace2-normal.sh

@@ -2,7 +2,6 @@
 
 test_description='test trace2 facility (normal target)'
 
-TEST_PASSES_SANITIZE_LEAK=false
 . ./test-lib.sh
 
 # Turn off any inherited trace2 settings for this test.

diff --git a/t/t0211-trace2-perf.sh b/t/t0211-trace2-perf.sh
index 070fe7a5da..b9421a64a7 100755
--- a/t/t0211-trace2-perf.sh
+++ b/t/t0211-trace2-perf.sh

@@ -2,7 +2,6 @@
 
 test_description='test trace2 facility (perf target)'
 
-TEST_PASSES_SANITIZE_LEAK=false
 . ./test-lib.sh
 
 # Turn off any inherited trace2 settings for this test.