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miedzinski opened this issue Jun 18, 2016 · 9 comments · Fixed by #1953
Closed

Crash on starred expression (*expr within a list expression) #1722

miedzinski opened this issue Jun 18, 2016 · 9 comments · Fixed by #1953
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@gvanrossum
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bug mypy got something wrong crash

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@miedzinski
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[1, *[2, 3]]

Traceback (most recent call last):
  File "/home/dominik/.virtualenvs/mypy/bin/mypy", line 6, in <module>
    main(__file__)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/main.py", line 54, in main
    res = type_check_only(sources, bin_dir, options)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/main.py", line 102, in type_check_only
    python_path=options.python_path)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 211, in build
    dispatch(sources, manager)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 1336, in dispatch
    process_graph(graph, manager)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 1467, in process_graph
    process_stale_scc(graph, scc)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 1497, in process_stale_scc
    graph[id].type_check()
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 1316, in type_check
    manager.type_checker.visit_file(self.tree, self.xpath)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 426, in visit_file
    self.accept(d)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 476, in accept
    typ = node.accept(self)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/nodes.py", line 729, in accept
    return visitor.visit_expression_stmt(self)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 1582, in visit_expression_stmt
    self.accept(s.expr)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 476, in accept
    typ = node.accept(self)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/nodes.py", line 1434, in accept
    return visitor.visit_list_expr(self)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 2122, in visit_list_expr
    return self.expr_checker.visit_list_expr(e)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checkexpr.py", line 1251, in visit_list_expr
    e)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checkexpr.py", line 1270, in check_list_or_set_expr
    [nodes.ARG_POS] * len(items), context)[0]
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checkexpr.py", line 242, in check_call
    messages=arg_messages)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checkexpr.py", line 661, in check_argument_types
    actual + 1, i + 1, callee, context, messages)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checkexpr.py", line 686, in check_arg
    elif not is_subtype(caller_type, callee_type):
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/subtypes.py", line 49, in is_subtype
    return left.accept(SubtypeVisitor(right, type_parameter_checker))
AttributeError: 'NoneType' object has no attribute 'accept'

$ python --version
Python 3.5.0+
$ mypy --version
mypy 0.4.2
@miedzinski
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miedzinski commented Jun 18, 2016 •
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feaabde (0.4.3-dev) has the same issue, but traceback is different:

Traceback (most recent call last):
  File "/home/dominik/.virtualenvs/mypy/bin/mypy", line 6, in <module>
    main(__file__)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/main.py", line 55, in main
    res = type_check_only(sources, bin_dir, options)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/main.py", line 103, in type_check_only
    python_path=options.python_path)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 215, in build
    dispatch(sources, manager)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 1335, in dispatch
    process_graph(graph, manager)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 1466, in process_graph
    process_stale_scc(graph, scc)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 1496, in process_stale_scc
    graph[id].type_check()
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 1315, in type_check
    manager.type_checker.visit_file(self.tree, self.xpath)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 431, in visit_file
    self.accept(d)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 481, in accept
    typ = node.accept(self)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/nodes.py", line 727, in accept
    return visitor.visit_expression_stmt(self)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 1605, in visit_expression_stmt
    self.accept(s.expr)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 481, in accept
    typ = node.accept(self)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/nodes.py", line 1432, in accept
    return visitor.visit_list_expr(self)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 2150, in visit_list_expr
    return self.expr_checker.visit_list_expr(e)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checkexpr.py", line 1266, in visit_list_expr
    e)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checkexpr.py", line 1274, in check_list_or_set_expr
    tvdef = TypeVarDef('T', -1, [], self.chk.object_type())
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 2256, in object_type
    return self.named_type('builtins.object')
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 2234, in named_type
    sym = self.lookup_qualified(name)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 2324, in lookup_qualified
    n = self.modules[parts[0]]
KeyError: 'builtins'

If it's not supported, mypy should raise an error like it does for print([1, *[2, 3]]) - error: Can use starred expression only as assignment target, although aforementioned build fails with the same traceback on this (0.4.2 does not crash).

EDIT:
git build behaves just like 0.4.2 -- looks like pip install https://github.com/python/mypy/archive/master.zip builds different package than pip install git+git://github.com/python/mypy.git.

@gvanrossum gvanrossum added bug mypy got something wrong crash labels Jun 23, 2016
@gvanrossum gvanrossum added this to the 0.4.x milestone Jun 23, 2016
@gnprice gnprice changed the title Starred expressions Crash on invalid syntax resembling *-args Jul 7, 2016
@JukkaL
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JukkaL commented Jul 8, 2016

The syntax is actually valid in Python 3.5:

>>> [1, *[2, 3]]
[1, 2, 3]

@JukkaL JukkaL changed the title Crash on invalid syntax resembling *-args Crash on *expr with a list expression Jul 8, 2016
@JukkaL
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JukkaL commented Jul 8, 2016

Another try with the title :-) Not sure what the correct term for these is.

@JukkaL JukkaL changed the title Crash on *expr with a list expression Crash on *expr within a list expression Jul 8, 2016
@miedzinski
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It is called starred expression in PEP 3132.

https://www.python.org/dev/peps/pep-3132/#specification

@JukkaL JukkaL changed the title Crash on *expr within a list expression Crash on starred expression (*expr within a list expression) Jul 8, 2016
@gvanrossum gvanrossum self-assigned this Jul 27, 2016
@gvanrossum
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I'm going to make this my next Dropbox Hack Week project.

@gvanrossum
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FWIW I can't repro the crash with the example as given, but this crashes (with a different traceback again):

(1, *(2, 3))

Anyway, the plan is to make it actually work.

@miedzinski
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Just installed mypy from PyPI and it produces the same traceback.

(mypy) dominik@ubuntu:/tmp$ python -V
Python 3.5.2
(mypy) dominik@ubuntu:/tmp$ apt-cache policy python3.5
python3.5:
  Installed: 3.5.2-2~16.01
  Candidate: 3.5.2-2~16.01
  Version table:
 *** 3.5.2-2~16.01 500
        500 http://pl.archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     3.5.1-10 500
        500 http://pl.archive.ubuntu.com/ubuntu xenial/main amd64 Packages
(mypy) $ mypy -V
mypy 0.4.3
(mypy) dominik@ubuntu:/tmp$ echo '[1, *[2, 3]]' > main.py
(mypy) dominik@ubuntu:/tmp$ mypy main.py
Traceback (most recent call last):
    main(__file__)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/main.py", line 40, in main
    res = type_check_only(sources, bin_dir, options)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/main.py", line 81, in type_check_only
    options=options)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 177, in build
    dispatch(sources, manager)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 1323, in dispatch
    process_graph(graph, manager)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 1461, in process_graph
    process_stale_scc(graph, scc)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 1538, in process_stale_scc
    graph[id].type_check()
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 1301, in type_check
    manager.type_checker.visit_file(self.tree, self.xpath)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 152, in visit_file
    self.accept(d)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 201, in accept
    typ = node.accept(self)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/nodes.py", line 737, in accept
    return visitor.visit_expression_stmt(self)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 1333, in visit_expression_stmt
    self.accept(s.expr)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 201, in accept
    typ = node.accept(self)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/nodes.py", line 1445, in accept
    return visitor.visit_list_expr(self)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 1859, in visit_list_expr
    return self.expr_checker.visit_list_expr(e)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checkexpr.py", line 1283, in visit_list_expr
    e)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checkexpr.py", line 1303, in check_list_or_set_expr
    [nodes.ARG_POS] * len(items), context)[0]
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checkexpr.py", line 253, in check_call
    messages=arg_messages)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checkexpr.py", line 677, in check_argument_types
    actual + 1, i + 1, callee, context, messages)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checkexpr.py", line 702, in check_arg
    elif not is_subtype(caller_type, callee_type):
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/subtypes.py", line 51, in is_subtype
    return left.accept(SubtypeVisitor(right, type_parameter_checker))
AttributeError: 'NoneType' object has no attribute 'accept'

*** INTERNAL ERROR ***

main.py:1: error: Internal error -- please report a bug at https://github.com/python/mypy/issues

NOTE: you can use "mypy --pdb ..." to drop into the debugger when this happens.

(1, *(2, 3)) crashes with different traceback:

(mypy) dominik@ubuntu:/tmp$ echo '(1, *(2, 3))' > main.py
(mypy) dominik@ubuntu:/tmp$ mypy main.py
Traceback (most recent call last):
  File "/home/dominik/.virtualenvs/mypy/bin/mypy", line 6, in <module>
    main(__file__)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/main.py", line 40, in main
    res = type_check_only(sources, bin_dir, options)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/main.py", line 81, in type_check_only
    options=options)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 177, in build
    dispatch(sources, manager)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 1323, in dispatch
    process_graph(graph, manager)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 1461, in process_graph
    process_stale_scc(graph, scc)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 1538, in process_stale_scc
    graph[id].type_check()
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/build.py", line 1301, in type_check
    manager.type_checker.visit_file(self.tree, self.xpath)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 152, in visit_file
    self.accept(d)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 201, in accept
    typ = node.accept(self)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/nodes.py", line 737, in accept
    return visitor.visit_expression_stmt(self)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 1333, in visit_expression_stmt
    self.accept(s.expr)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 201, in accept
    typ = node.accept(self)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/nodes.py", line 1477, in accept
    return visitor.visit_tuple_expr(self)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checker.py", line 1865, in visit_tuple_expr
    return self.expr_checker.visit_tuple_expr(e)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/checkexpr.py", line 1324, in visit_tuple_expr
    fallback_item = join.join_type_list(items)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/join.py", line 358, in join_type_list
    joined = join_types(joined, t)
  File "/home/dominik/.virtualenvs/mypy/lib/python3.5/site-packages/mypy/join.py", line 73, in join_types
    return t.accept(TypeJoinVisitor(s))
AttributeError: 'NoneType' object has no attribute 'accept'

*** INTERNAL ERROR ***

main.py:1: error: Internal error -- please report a bug at https://github.com/python/mypy/issues

NOTE: you can use "mypy --pdb ..." to drop into the debugger when this happens.

@gvanrossum
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Yeah, I can repro it with 0.4.3 too. It seems something happened since the release of 0.4.3 that made that particular crash disappear.

@gvanrossum
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Related: #704. PEP 448 defines this new syntax.

@gvanrossum gvanrossum mentioned this issue Jul 28, 2016
Merged
gvanrossum added a commit that referenced this issue Jul 29, 2016
@gvanrossum
Support star expressions in lists, tuples, sets (#1953)
da0576e 
This fixes #1722 and addresses most of #704 (but doesn't close it, because of {**x}).
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Support star expressions in lists, tuples, sets python/mypy
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@JukkaL @gvanrossum @miedzinski