This may be related to the changes in https://bugs.python.org/issue42246. Could you open a new issue and add Mark Shannon to it if that turns to be the case?
Pablo On Mon, 11 Jan 2021 at 19:36, Chris Angelico <ros...@gmail.com> wrote: > On Tue, Jan 12, 2021 at 6:00 AM Mats Wichmann <m...@wichmann.us> wrote: > > > > > > On 1/8/21 4:31 PM, Mats Wichmann wrote: > > > > > > > > > Someone reported a testsuite break on stuff I work on (scons) with > > > 3.10a4, and it looks similar to this which appears in the changelog at > > > > > > https://docs.python.org/3.10/whatsnew/changelog.html#changelog > > > > > > bpo-23898: Fix inspect.classify_class_attrs() to support attributes > with > > > overloaded __eq__ and __bool__. Patch by Mike Bayer. > > > > > > Except when I go look at that BPO issue, it's old - closed 2015. Is > > > this appearing in the 3.10 changelog in error? Sorry - confused !!! > > > > okay, that was silly, I didn't realize the changelog was cumulative over > > many versions, so that entry was not for 3.10 at all (teach me to do > > searching in browser window, where it just flies right past any section > > headings so I miss it was for a different version :) ). > > > > > The test in question does indeed touch a class which overrides __bool_ > > > in order to raise an exception (to say "don't do that"), and in the > test > > > run the (expected) exception is not raised. > > > > So updated information: the test in question is checking if a class (A) > > has an attribute using a truth test, where the attribute's value is an > > instance of another class (B) and expecting that that will cause the > > __bool__ method to be called. [aside: this test is done to validate that > > a class which really doesn't want this kind of test indeed rejects it] > > That apparently no longer happens, if it's wrapped in a try block ??? > > Distilled down to simple case: > > > > class A: > > pass > > > > class B: > > def __bool__(self): > > raise AttributeError("don't do that!") > > > > a = A() > > b = B() > > a.b = b > > # expect this to cause b.__bool__ to be called > > if a.b: > > print("Found it!") > > > > and it raises the exception. But when protected: > > > > try: > > if a.b: > > pass > > except AttributeError: > > print("Got expected exception") > > else: > > print("Missed expected exception") > > > > it won't trigger. But if I add a "real" statement in the block following > > the "if", then it's back to the pre-3.10 behavior of calling __bool__: > > > > try: > > if a.b: > > dummy = True > > except AttributeError: > > print("Got expected exception") > > else: > > print("Missed expected exception") > > > > > > Any thoughts on this? > > Oooh interesting. I tried on a build of 3.10 from October and: > 1) The unguarded version bombed out with an exception > 2) The "if... pass" version reported that it got the exception > 3) The "if... dummy" version reported that it got the exception > > ie every one of them did indeed raise. But on a fresh build from the > master branch, I got the same results you did. That means the change > happened some time between commit 497126f7ea and commit ace008c531, an > 800ish commit span. > > I'll start bisecting to try to track this down. It looks like "if a.b: > pass" is getting partially optimized out; the disassembly shows a > being loaded, its attribute b being looked up, and then it just jumps > to the else - there's no POP_JUMP_IF_FALSE as there is when there's a > bit of actual code in there. > > ChrisA > _______________________________________________ > Python-Dev mailing list -- python-dev@python.org > To unsubscribe send an email to python-dev-le...@python.org > https://mail.python.org/mailman3/lists/python-dev.python.org/ > Message archived at > https://mail.python.org/archives/list/python-dev@python.org/message/K2LD2L5RF2ZFUYEXQ3Z5U4TY5QBRFPCQ/ > Code of Conduct: http://python.org/psf/codeofconduct/ >
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