False positive errors with anonymous and inline declaration of namedtuple types
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Description
Bug Report
Mypy raises false positive errors with anonymous and inline declaration of namedtuple types.
To Reproduce
from collections import namedtuple
dim = namedtuple("Dimension", ["x", "y"])(2, 3)
This should be equivalent to the following, which mypy gets correct:
from collections import namedtuple
Dimension = namedtuple("Dimension", ["x", "y"])
dim = Dimension(2, 3)
(Example taken from here: https://stackoverflow.com/a/26405216)
Expected Behavior
No error raised.
Actual Behavior
$ mypy namedtuple.py
namedtuple.py:3: error: Too many arguments for "tuple" [call-arg]
namedtuple.py:3: error: Argument 1 to "tuple" has incompatible type "int"; expected "Iterable[Any]" [arg-type]
Found 2 errors in 1 file (checked 1 source file)
My Environment
$ mypy --version
mypy 1.7.1 (compiled: yes)
$ python --version
Python 3.11.6
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the report with namedtuple.py and the inline anonymous declaration shown in the issue, then compare it with the separate Dimension declaration. Trace mypy's handling of collections.namedtuple calls. Done means the inline form produces no false-positive errors while the existing separate-declaration example remains correct.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- devtools
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Clearly specified
- Newbie friendliness
- 35/100