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Crash with forward reference in NamedTuple #3315
Description
Found this testing my production codebase against mypy master:
(venv) jelle@devjelle:~/mypy$ cat testnt.py
from typing import NamedTuple
class A(NamedTuple):
b: 'B'
x: int
class B:
pass
(venv) jelle@devjelle:~/mypy$ python -m mypy --show-traceback testnt.py
testnt.py:3: error: INTERNAL ERROR -- please report a bug at https://github.com/python/mypy/issues version: 0.510-dev-09e7b124b82dae1207d9eac6805b64a98290015c
Traceback (most recent call last):
File "/home/jelle/ans/venv64/lib/python3.6/runpy.py", line 193, in _run_module_as_main
"__main__", mod_spec)
File "/home/jelle/ans/venv64/lib/python3.6/runpy.py", line 85, in _run_code
exec(code, run_globals)
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/__main__.py", line 5, in <module>
main(None)
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/main.py", line 46, in main
res = type_check_only(sources, bin_dir, options)
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/main.py", line 93, in type_check_only
options=options)
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/build.py", line 188, in build
graph = dispatch(sources, manager)
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/build.py", line 1595, in dispatch
process_graph(graph, manager)
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/build.py", line 1838, in process_graph
process_stale_scc(graph, scc, manager)
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/build.py", line 1931, in process_stale_scc
graph[id].semantic_analysis()
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/build.py", line 1495, in semantic_analysis
self.manager.semantic_analyzer.visit_file(self.tree, self.xpath, self.options)
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/semanal.py", line 257, in visit_file
self.accept(d)
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/semanal.py", line 3279, in accept
node.accept(self)
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/nodes.py", line 749, in accept
return visitor.visit_class_def(self)
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/semanal.py", line 617, in visit_class_def
with self.analyze_class_body(defn) as should_continue:
File "/home/jelle/ans/venv64/lib/python3.6/contextlib.py", line 82, in __enter__
return next(self.gen)
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/semanal.py", line 629, in analyze_class_body
if self.analyze_namedtuple_classdef(defn):
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/semanal.py", line 819, in analyze_namedtuple_classdef
defn.name, items, types, default_items)
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/semanal.py", line 2053, in build_namedtuple_typeinfo
fallback = self.named_type('__builtins__.tuple', [join.join_type_list(types)])
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/join.py", line 388, in join_type_list
joined = join_types(joined, t)
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/join.py", line 88, in join_types
return t.accept(TypeJoinVisitor(s))
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/types.py", line 411, in accept
return visitor.visit_instance(self)
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/join.py", line 141, in visit_instance
return join_instances(t, self.s)
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/join.py", line 295, in join_instances
return join_instances_via_supertype(s, t)
File "/home/jelle/mypy/venv/lib/python3.6/site-packages/mypy/join.py", line 314, in join_instances_via_supertype
assert best is not None
AssertionError:
testnt.py:3: note: use --pdb to drop into pdb
Haven't tried yet to minimize this further. Hopefully we can get this fixed before the release.
Edit: this also repros with TypedDict:
from mypy_extensions import TypedDict
X = TypedDict('X', {'b': 'B', 'c': int})
class B: pass
Activity
JelleZijlstra commentedon May 4, 2017
Reverting #3305 fixes it (cc @ilevkivskyi).
gvanrossum commentedon May 4, 2017
Thanks for testing! We should get to this one way or another before the release. @JukkaL.
ilevkivskyi commentedon May 4, 2017
My PR surfaced the bug already present in
TypedDict, we need to postpone the join in fallback instance argument until third pass, since MROs are not yet calculated. I will take a look at this now.ilevkivskyi commentedon May 4, 2017
OK, I have fixed these two crashes and also three crashes from #3308 (for both class and functional syntax, total nine crash scenarios). I will now add tests and make a PR.
The point is that "synthetic" types were sometimes ignored in the third pass, now they are correctly processed.
JukkaL commentedon May 4, 2017
I'm working on a quick fix that just uses
Anyin the fallback for named tuples. The TypedDict issue is also present in the previous release, I think, so it's less urgent. (Also TypedDict is not even documented yet.)JukkaL commentedon May 4, 2017
Created a separate issue for the TypedDict crash so that these can be tracked independently (#3319).
Remove use of join during semantic analysis
Fix crash caused by forward reference in NamedTuple (#3320)