Schema build runs forever on main

[samuelcolvin]

Initial Checks

• I confirm that I'm using Pydantic V2

Description

Run the below code and building the schema runs forever.

Oddly it doesn't if:

• you remove Ham from the union, still takes a long time but not forever
• move the definition of DiscUnion to the end of the file, in this case it's very fast
• use 2.4.2

Example Code

from __future__ import annotations as _annotations

from pydantic import BaseModel


class Foo(BaseModel):
    f: DiscUnion


class Bar(BaseModel):
    b: DiscUnion


class Spam(BaseModel):
    s: DiscUnion


class Egg(BaseModel):
    e: DiscUnion


class Ham(BaseModel):
    h: DiscUnion


DiscUnion = Foo | Bar | Spam | Egg | Ham


class Final(BaseModel):
    d: DiscUnion

Python, Pydantic & OS Version

Using current main da2173ed6d7065d1f89236824403bf758b86f20d