Inherit Pydantic BaseModel with optional generic attributes inside a function block

Crash Report
Mypy reports INTERNAL ERROR: maximum semantic analysis iteration count reached when defining a class that inherits a pydantic BaseModel with optional generic arguments inside a function block.

Traceback

Deferral trace:
    local_mypy_debug:16
    local_mypy_debug:16
    local_mypy_debug:16
    local_mypy_debug:16
    local_mypy_debug:16
    local_mypy_debug:16
    local_mypy_debug:16
    local_mypy_debug:16
    local_mypy_debug:16
    local_mypy_debug:16
    local_mypy_debug:16
    local_mypy_debug:16
    local_mypy_debug:16
    local_mypy_debug:16
    local_mypy_debug:16
    local_mypy_debug:16
    local_mypy_debug:16
    local_mypy_debug:16
    local_mypy_debug:16
Deferral trace:
    local_mypy_debug:21
    local_mypy_debug:21
    local_mypy_debug:21
    local_mypy_debug:21
    local_mypy_debug:21
    local_mypy_debug:21
    local_mypy_debug:21
    local_mypy_debug:21
    local_mypy_debug:21
    local_mypy_debug:21
    local_mypy_debug:21
    local_mypy_debug:21
    local_mypy_debug:21
    local_mypy_debug:21
    local_mypy_debug:21
    local_mypy_debug:21
    local_mypy_debug:21
    local_mypy_debug:21
    local_mypy_debug:21
local_mypy_debug.py: error: INTERNAL ERROR: maximum semantic analysis iteration count reached
Found 1 error in 1 file (errors prevented further checking)

To Reproduce

from pydantic import BaseModel
from typing import Optional, TypeVar, Generic

T = TypeVar("T")

class ClassWithOptionalGenericAttr(BaseModel, Generic[T]):
    attr: Optional[T]

# Case 1: This passes.
class B(ClassWithOptionalGenericAttr[T]):
    pass


# Case 2: Mypy: INTERNAL ERROR: maximum semantic analysis iteration count reached
def define_inside_a_func_with_generic() -> None:
    class B(ClassWithOptionalGenericAttr[T]):
        pass

# Case 3: Mypy: INTERNAL ERROR: maximum semantic analysis iteration count reached
def define_inside_a_func_with_type() -> None:
    class B(ClassWithOptionalGenericAttr[str]):
        pass


class ClassWithNonOptionalGenericAttr(BaseModel, Generic[T]):
    attr: T

# Case 4: This passes.
def define_inside_a_func_with_non_optional() -> None:
    class B(ClassWithNonOptionalGenericAttr[T]):
        pass

Your Environment

• Mypy version used: mypy 1.8.0 (compiled: yes)
• Mypy command-line flags: python -m mypy --show-traceback local_mypy_debug.py
• Mypy configuration options from mypy.ini (and other config files):
• Python version used: 3.9.15
• Operating system and version: macOS Sonoma Version 14.3

Start with the local_mypy_debug.py reproducer and run the reported python -m mypy --show-traceback command, comparing the four class-definition cases and their semantic-analysis deferrals. Done means the reproducer no longer reaches the maximum semantic analysis iteration count, with coverage for the optional generic cases.