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INTERNAL ERROR on match-case statement
Bug Report
The following causes an INTERNAL ERROR
. The issue seems to be related to the usage of match-case.
https://mypy-play.net/?mypy=master&python=3.12&flags=show-traceback&gist=7ccec270743b3e26d66d211839e82e64
To Reproduce
from typing import Self, Protocol, overload
from collections.abc import Sequence
class Encoder(Protocol):
def __call__(self, u, /): ...
def simplify(self) -> "Encoder":
return self
class Chain(Encoder, Sequence[Encoder]):
encoders: list[Encoder]
def __init__(self, *encoders: Encoder):
self.encoders = list(encoders)
def __len__(self) -> int:
return len(self.encoders)
@overload
def __getitem__(self, index: int) -> Encoder: ...
@overload
def __getitem__(self, index: slice) -> Self: ...
def __getitem__(self, index, /):
return self.encoders[index]
def __call__(self, x):
for encoder in self.encoders:
x = encoder(x)
return x
def simplify(self) -> Encoder | Self:
match self:
case [encoder]:
return encoder.simplify()
case _:
cls = type(self)
return cls(*(e.simplify() for e in self.encoders))
# The equivalent code below works...
# if len(self)==1:
# return self.encoders[0].simplify()
# cls = type(self)
# return cls(*(e.simplify() for e in self.encoders))
Actual Behavior
main.py:33: error: INTERNAL ERROR -- Please try using mypy master on GitHub:
https://mypy.readthedocs.io/en/stable/common_issues.html#using-a-development-mypy-build
If this issue continues with mypy master, please report a bug at https://github.com/python/mypy/issues
version: 1.11.0+dev.0570f71f000489c94021d956662ab3373f7296bc
main.py:33: : note: please use --show-traceback to print a traceback when reporting a bug
Full Traceback
Traceback (most recent call last):
File "<frozen runpy>", line 198, in _run_module_as_main
File "<frozen runpy>", line 88, in _run_code
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/__main__.py", line 37, in <module>
console_entry()
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/__main__.py", line 15, in console_entry
main()
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/main.py", line 100, in main
res, messages, blockers = run_build(sources, options, fscache, t0, stdout, stderr)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/main.py", line 182, in run_build
res = build.build(sources, options, None, flush_errors, fscache, stdout, stderr)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/build.py", line 192, in build
result = _build(
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/build.py", line 266, in _build
graph = dispatch(sources, manager, stdout)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/build.py", line 2942, in dispatch
process_graph(graph, manager)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/build.py", line 3340, in process_graph
process_stale_scc(graph, scc, manager)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/build.py", line 3441, in process_stale_scc
graph[id].type_check_first_pass()
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/build.py", line 2310, in type_check_first_pass
self.type_checker().check_first_pass()
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checker.py", line 481, in check_first_pass
self.accept(d)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checker.py", line 589, in accept
stmt.accept(self)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/nodes.py", line 1142, in accept
return visitor.visit_class_def(self)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checker.py", line 2340, in visit_class_def
self.accept(defn.defs)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checker.py", line 589, in accept
stmt.accept(self)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/nodes.py", line 1223, in accept
return visitor.visit_block(self)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checker.py", line 2802, in visit_block
self.accept(s)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checker.py", line 589, in accept
stmt.accept(self)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/nodes.py", line 787, in accept
return visitor.visit_func_def(self)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checker.py", line 1000, in visit_func_def
self._visit_func_def(defn)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checker.py", line 1004, in _visit_func_def
self.check_func_item(defn, name=defn.name)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checker.py", line 1077, in check_func_item
self.check_func_def(defn, typ, name, allow_empty)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checker.py", line 1309, in check_func_def
self.accept(item.body)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checker.py", line 589, in accept
stmt.accept(self)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/nodes.py", line 1223, in accept
return visitor.visit_block(self)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checker.py", line 2802, in visit_block
self.accept(s)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checker.py", line 589, in accept
stmt.accept(self)
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/nodes.py", line 1607, in accept
return visitor.visit_match_stmt(self)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checker.py", line 5107, in visit_match_stmt
pattern_types = [self.pattern_checker.accept(p, subject_type) for p in s.patterns]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checkpattern.py", line 129, in accept
result = o.accept(self)
^^^^^^^^^^^^^^
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/patterns.py", line 93, in accept
return visitor.visit_sequence_pattern(self)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checkpattern.py", line 335, in visit_sequence_pattern
new_type = self.construct_sequence_child(current_type, new_inner_type)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checkpattern.py", line 756, in construct_sequence_child
assert isinstance(proper_type, Instance)
AssertionError:
main.py:33: error: INTERNAL ERROR -- Please try using mypy master on GitHub:
https://mypy.readthedocs.io/en/stable/common_issues.html#using-a-development-mypy-build
Please report a bug at https://github.com/python/mypy/issues
version: 1.11.0+dev.0570f71f000489c94021d956662ab3373f7296bc
main.py:33: : note: use --pdb to drop into pdb
Your Environment
https://mypy-play.net/?mypy=master&python=3.12&flags=show-traceback&gist=7ccec270743b3e26d66d211839e82e64
Some of the traceback (from mypy-play):
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checker.py", line 5107, in visit_match_stmt
pattern_types = [self.pattern_checker.accept(p, subject_type) for p in s.patterns]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checkpattern.py", line 129, in accept
result = o.accept(self)
^^^^^^^^^^^^^^
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/patterns.py", line 93, in accept
return visitor.visit_sequence_pattern(self)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checkpattern.py", line 335, in visit_sequence_pattern
new_type = self.construct_sequence_child(current_type, new_inner_type)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/checkpattern.py", line 756, in construct_sequence_child
assert isinstance(proper_type, Instance)
AssertionError
Looks like a missed case in the match implementation.