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Two crashes on recursive named tuples #3340
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This was referenced Jul 7, 2017
JukkaL
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Sep 27, 2017
Forward references didn't work with anything apart from classes, for example this didn't work: ``` x: A A = NamedTuple('A', [('x', int)]) ``` The same situation was with `TypedDict`, `NewType`, and type aliases. The root problem is that these synthetic types are neither detected in first pass, nor fixed in third pass. In certain cases this can lead to crashes (first six issues below are various crash scenarios). This fixes these crashes by applying some additional patches after third pass. Here is the summary of the PR: * New simple wrapper type `ForwardRef` with only one field `link` is introduced (with updates to type visitors) * When an unknown type is found in second pass, the corresponding `UnboundType` is wrapped in `ForwardRef`, it is given a "second chance" in third pass. * After third pass I record the "suspicious" nodes, where forward references and synthetic types have been encountered and append patches (callbacks) to fix them after third pass. Patches use the new visitor `TypeReplacer` (which is the core of this PR). Fixes #3340 Fixes #3419 Fixes #3674 Fixes #3685 Fixes #3799 Fixes #3836 Fixes #3881 Fixes #867 Fixes #2241 Fixes #2399 Fixes #1701 Fixes #3016 Fixes #3054 Fixes #2762 Fixes #3575 Fixes #3990
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While working on #3322 I have found two more crashes:
crashes with
RecursionError
andcrashes with
AssertionError
injoin_instances_via_supertype
. I didn't tryTypedDict
but most probably it will have similar problems.There is actually a fundamental question here: what should be the
join(N, M)
? @JukkaL do you have any ideas? One possible option would be to detect recursive joins and just returnobject
for them (maybe alsoUninhabitedType
for recursive meets).The text was updated successfully, but these errors were encountered: