Does not recognize __func__ of methods

seems similar to #2563, #3482, #8869, #11211, #12673 -- though those are mostly about decorated descriptors

Bug Report

simple, silly example:

class C:
    def f(self) -> None: pass

    def g(self) -> None:
        print(self.f.__func__)

C().g()

Expected Behavior

no error

Actual Behavior

$ ./.venv/bin/mypy t.py
t.py:5: error: "Callable[[], None]" has no attribute "__func__"  [attr-defined]
Found 1 error in 1 file (checked 1 source file)
$ ./.venv/bin/mypy --version
mypy 0.991 (compiled: yes)

Your Environment

• Mypy version used: 0.991
• Mypy command-line flags: N/A
• Mypy configuration options from mypy.ini (and other config files): N/A
• Python version used: 3.8.10

Start by reproducing the report with the Python snippet in t.py and the documented mypy 0.991 command. Trace how mypy infers the type of self.f and handles access to func. Done means the example type-checks without the attr-defined error while existing method and descriptor checks remain passing.