[lldb-dev] Updating or removing lldb's copy of unittest2

[Jonas Devlieghere via lldb-dev]

Hey David,

On Thu, Jan 28, 2021 at 2:46 AM David Spickett via lldb-dev <
lldb-dev at lists.llvm.org> wrote:

> I came across a minor bug writing some lldb-server tests where single
> line diffs weren't handled correctly by unittest2. Turns out they are
> in the latest version but the third_party/ version is older than that.
>
> https://bugs.python.org/issue9174
> https://hg.python.org/unittest2/rev/96e432563d53 (though I think the
> commit title is a mistake)
>
> So I thought of cherry picking that one thing (assuming licensing
> would allow me to), or even updating the whole copy (a lot of churn
> for a single fix). Then I remembered that llvm in general has been
> moving to Python3.
>

I made an attempt to update the vendored unittest2 module in the past [1].
I diffed our vendored version with the release it was based on, updated the
module and re-applied the changes. That was the easy part. The more
intrusive part is that the testing framework changed the way it deals with
expected failures. The old version used exceptions, while the new framework
only looks at asserts that fail. I don't remember the details, but we are
relying on that mechanism somehow and as a result a bunch of test failed.
The good thing is that this uncovered a few tests that were XFAILed but
were really failing for unrelated reasons (i.e. Python throwing
an exception because the test was plain wrong, rather than an assertion
triggering or what was being tested not working). Anyway, hopefully this
isn't too much work, but at the time something more important came up and I
haven't had time to look at this again since.


> Looking at https://lldb.llvm.org/resources/build.html it doesn't
> explicitly say Python2 isn't supported, but only Python3 is mentioned
> so I assume lldb is now Python3 only.
>

LLVM dropped support for Python 2 at the beginning of this year [2]. For
LLDB specifically, I've asked for a bit more time before we start making
"Python 2 incompatible" changes [3] as we still have to maintain Python 2
support internally. We're actively working to drop that requirement.


> If that is correct, is it worth me investigating using Python3's built
> in unittest module instead, and removing our copy of unittest2?
>

I'm in favor of dropping a vendored dependency, assuming of course we can
get rid of the modification we rely on today. If we go that route I want to
ask to land this after the 13 release is branched.

Cheers,
Jonas

[1]
https://github.com/JDevlieghere/llvm-project/tree/update-vendored-unittest2
[2] https://lists.llvm.org/pipermail/llvm-dev/2020-December/147372.html
[3] https://lists.llvm.org/pipermail/lldb-dev/2020-August/016388.html


> Thanks,
> David Spickett.
> _______________________________________________
> lldb-dev mailing list
> lldb-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/lldb-dev/attachments/20210128/956ad776/attachment.html>