Infinite recursion error if a field has the same name as its type

[guillaume-alliander]

Initial Checks

• I confirm that I'm using Pydantic V2

Description

If a field has the same name as its type, and is defined with Field(), then a RecursionError happens,

In the example below:

• this is true with pydantic dataclass or BaseModel
• using the default python dataclass, this does not happen
• if =Field() is not given, this does not happen
• it seems to only happen if the type of the field is another Pydantic object (int: int or Path:Path with from pathlib import Path are both fine)

The given snippet is enough to blow python up.

My expectation would be to see "42" if I add:

o=Other(Thing=Thing(i=42))
print(o.Thing.i)

Which is the case if I use python's dataclasses.

Example Code

# from dataclasses import dataclass # works
from pydantic import Field
from pydantic.dataclasses import dataclass  # blows up


@dataclass
class Thing:
    i:int

@dataclass
class Other:
    Thing: Thing=Field() # Works if Field is no present

Python, Pydantic & OS Version

python -c "import pydantic.version; print(pydantic.version.version_info())"                                                             0s - 11:48:19
             pydantic version: 2.5.0
        pydantic-core version: 2.14.1
          pydantic-core build: profile=release pgo=true
                 install path: /home/gui/.conda/envs/pycgmes10/lib/python3.10/site-packages/pydantic
               python version: 3.10.11 (main, Apr 20 2023, 19:02:41) [GCC 11.2.0]
                     platform: Linux-5.10.102.1-microsoft-standard-WSL2-x86_64-with-glibc2.35
             related packages: pyright-1.1.335 typing_extensions-4.8.0 mypy-1.5.1

[Viicos]

Duplicate of: #7327 (you will find explanation and related issues here).
I'll take a look to see if it's possible to have a better error message here as this issue comes up pretty often.

[sydney-runkle]

I'm wondering if it makes sense to have a "common mistakes" section of the docs that highlights issues like this one that we see pop up more than once a month.

[sydney-runkle]

Marking as fixed by #8243