mypy does not recognize collections within collections

[Koraxtu]

Diagnostic Data

• Python version (& distribution if applicable, e.g., Anaconda): 3.10
• Type of virtual environment used (e.g., conda, venv, virtualenv, etc.): venv
• Operating system (and version): Windows 10, current version
• Version of tool extension you are using: current version of Mypy from a fresh install, no modifications

Behaviour

Expected Behavior

For no errors to be found.

Actual Behavior

I got an error and this is it:
"Sequence[Collection[str]]" has no attribute "append"Mypyattr-defined
(function) append: Any

Reproduction Steps:

1. Create a new python file
2. Create a collection that has another collection within that python file (eg: python list that contains a dictionary that contains a list)
3. Write code that uses any built-in method on an double-nested collection

Example:

stores = [
    {
        "name": "My Store",
        "items": [
            {
                "name": "Chair",
                "price": 15.99
            }
        ]
    }
]

for store in stores:
    if store["name"] == "pie":
        new_item = {"name": "request_data", "price": "price"}
        store["items"].append(new_item)

On line 16 of the example, Mypy detects an error with using the append method on the list within stores[0]["items"], aka store["items"]. But store["items"] is a list and can use the append method, this code runs without issue.

Logs:

Click here for detailed logs

2024-06-15 00:12:13.849 [info] file:///c%3A/...etc.../app.py : c:\Users\...etc...\app.py:34:13:34:33: error: "Sequence[Collection[str]]" has no attribute "append" [attr-defined]

Extra Details

Other Python extensions: isort, Pylance, Python Debugger, Python
Project structure (square brackets represent folders):
[pycache]
[.mypy_cache]
[.venv]
app.py

[karthiknadig]

This extension is a thin wrapper around mypy. This should be filed on https://github.com/python/mypy/issues