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refi64 opened this issue Oct 25, 2016 · 4 comments · Fixed by #2445
Closed

Internal error with generic type and alias using import * #2315

refi64 opened this issue Oct 25, 2016 · 4 comments · Fixed by #2445
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@refi64
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refi64 commented Oct 25, 2016

Dang, I'm on a bug roll today. :D

In x.py:

from y import *

notes = None  # type: G[X]
# Using the new annotation syntax `notes: G[X]` can also reproduce the crash.

y.py:

from typing import Generic, TypeVar

T = TypeVar('T')

class G(Generic[T]):
    pass

X = G[int]

Output:

ryan@DevPC-LX ~/blaze-mypy/bug master $ mypy x.py --show-traceback
x.py:1: error: INTERNAL ERROR -- please report a bug at https://github.com/python/mypy/issues
Traceback (most recent call last):
  File "/media/ryan/stuff/anaconda/bin/mypy", line 6, in <module>
    exec(compile(open(__file__).read(), __file__, 'exec'))
  File "/media/ryan/stuff/mypy/scripts/mypy", line 6, in <module>
    main(__file__)
  File "/media/stuff/anaconda/lib/python3.4/site-packages/mypy/main.py", line 38, in main
    res = type_check_only(sources, bin_dir, options)
  File "/media/stuff/anaconda/lib/python3.4/site-packages/mypy/main.py", line 79, in type_check_only
    options=options)
  File "/media/stuff/anaconda/lib/python3.4/site-packages/mypy/build.py", line 184, in build
    dispatch(sources, manager)
  File "/media/stuff/anaconda/lib/python3.4/site-packages/mypy/build.py", line 1494, in dispatch
    process_graph(graph, manager)
  File "/media/stuff/anaconda/lib/python3.4/site-packages/mypy/build.py", line 1674, in process_graph
    process_stale_scc(graph, scc)
  File "/media/stuff/anaconda/lib/python3.4/site-packages/mypy/build.py", line 1751, in process_stale_scc
    graph[id].semantic_analysis_pass_three()
  File "/media/stuff/anaconda/lib/python3.4/site-packages/mypy/build.py", line 1411, in semantic_analysis_pass_three
    self.manager.semantic_analyzer_pass3.visit_file(self.tree, self.xpath, self.options)
  File "/media/stuff/anaconda/lib/python3.4/site-packages/mypy/semanal.py", line 2871, in visit_file
    self.accept(file_node)
  File "/media/stuff/anaconda/lib/python3.4/site-packages/mypy/semanal.py", line 2875, in accept
    node.accept(self)
  File "/media/stuff/anaconda/lib/python3.4/site-packages/mypy/nodes.py", line 259, in accept
    return visitor.visit_mypy_file(self)
  File "/media/stuff/anaconda/lib/python3.4/site-packages/mypy/traverser.py", line 29, in visit_mypy_file
    d.accept(self)
  File "/media/stuff/anaconda/lib/python3.4/site-packages/mypy/nodes.py", line 815, in accept
    return visitor.visit_assignment_stmt(self)
  File "/media/stuff/anaconda/lib/python3.4/site-packages/mypy/semanal.py", line 2952, in visit_assignment_stmt
    self.analyze(s.type)
  File "/media/stuff/anaconda/lib/python3.4/site-packages/mypy/semanal.py", line 2972, in analyze
    type.accept(analyzer)
  File "/media/stuff/anaconda/lib/python3.4/site-packages/mypy/types.py", line 427, in accept
    return visitor.visit_instance(self)
  File "/media/stuff/anaconda/lib/python3.4/site-packages/mypy/typeanal.py", line 363, in visit_instance
    if not satisfies_upper_bound(arg, TypeVar.upper_bound):
  File "/media/stuff/anaconda/lib/python3.4/site-packages/mypy/subtypes.py", line 75, in satisfies_upper_bound
    return isinstance(a, Void) or is_subtype(a, upper_bound)
  File "/media/stuff/anaconda/lib/python3.4/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'
x.py:1: note: use --pdb to drop into pdb
ryan@DevPC-LX ~/blaze-mypy/bug master $
@gvanrossum
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Reproduced.

@gvanrossum gvanrossum added this to the 0.4.x milestone Oct 25, 2016
@davire
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davire commented Nov 8, 2016

Another example that raises the issue without generic type:

file ex2a.py

from typing import Dict

Row = Dict[str, int]

file ex2.py

from ex2a import *

def do_something(dic: Row) -> None:
    pass

results in :

mypy --show-traceback ex2.py 
ex2.py:1: error: INTERNAL ERROR -- please report a bug at https://github.com/python/mypy/issues
Traceback (most recent call last):
  File "/usr/local/bin/mypy", line 6, in <module>
    main(__file__)
  File "/usr/local/lib/python3.5/site-packages/mypy/main.py", line 38, in main
    res = type_check_only(sources, bin_dir, options)
  File "/usr/local/lib/python3.5/site-packages/mypy/main.py", line 79, in type_check_only
    options=options)
  File "/usr/local/lib/python3.5/site-packages/mypy/build.py", line 181, in build
    dispatch(sources, manager)
  File "/usr/local/lib/python3.5/site-packages/mypy/build.py", line 1470, in dispatch
    process_graph(graph, manager)
  File "/usr/local/lib/python3.5/site-packages/mypy/build.py", line 1650, in process_graph
    process_stale_scc(graph, scc)
  File "/usr/local/lib/python3.5/site-packages/mypy/build.py", line 1723, in process_stale_scc
    graph[id].semantic_analysis_pass_three()
  File "/usr/local/lib/python3.5/site-packages/mypy/build.py", line 1406, in semantic_analysis_pass_three
    self.manager.semantic_analyzer_pass3.visit_file(self.tree, self.xpath, self.options)
  File "/usr/local/lib/python3.5/site-packages/mypy/semanal.py", line 2770, in visit_file
    self.accept(file_node)
  File "/usr/local/lib/python3.5/site-packages/mypy/semanal.py", line 2774, in accept
    node.accept(self)
  File "/usr/local/lib/python3.5/site-packages/mypy/nodes.py", line 216, in accept
    return visitor.visit_mypy_file(self)
  File "/usr/local/lib/python3.5/site-packages/mypy/traverser.py", line 29, in visit_mypy_file
    d.accept(self)
  File "/usr/local/lib/python3.5/site-packages/mypy/nodes.py", line 507, in accept
    return visitor.visit_func_def(self)
  File "/usr/local/lib/python3.5/site-packages/mypy/semanal.py", line 2785, in visit_func_def
    self.analyze(fdef.type)
  File "/usr/local/lib/python3.5/site-packages/mypy/semanal.py", line 2871, in analyze
    type.accept(analyzer)
  File "/usr/local/lib/python3.5/site-packages/mypy/types.py", line 639, in accept
    return visitor.visit_callable_type(self)
  File "/usr/local/lib/python3.5/site-packages/mypy/typeanal.py", line 381, in visit_callable_type
    arg_type.accept(self)
AttributeError: 'NoneType' object has no attribute 'accept'
ex2.py:1: note: use --pdb to drop into pdb

@davire
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davire commented Nov 8, 2016

Note that in the previous example, if you replace from ex2a import * with from ex2a import Row, the internal error disappears.

@gvanrossum
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I'm thinking the issue has to do with "import *" mistreating certain types and aliases.

@gvanrossum gvanrossum changed the title Internal error with generic type and alias across modules Internal error with generic type and alias using import * Nov 8, 2016
@refi64 refi64 mentioned this issue Nov 11, 2016
Closed
@ilevkivskyi ilevkivskyi mentioned this issue Nov 13, 2016
Merged
gvanrossum pushed a commit that referenced this issue Nov 14, 2016
@ilevkivskyi @gvanrossum
Fix crashes with import * (#2445)
19629d5 
Fixes #2315
Fixes #2172

There were reported some crashes of mypy when using import * and type aliases (only two above issues seem to be still open, others are closed as duplicates).

It looks like this is because visit_import_all in semanal.py does not copy type_override for imported nodes (visit_import_from does, so that the crashes reported happen only with import *).

I added few tests based on (extended) examples discussed in bug reports. Since the reason is clear and the fix is straightforward (one line) I think more sophisticated tests are not required.
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Fix crashes with import * and aliases ilevkivskyi/mypy
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@davire @refi64 @gvanrossum