New type inference processes `itertools.groupby` key as `Any`

Bug Report

Given code like:

import itertools

for grouper, members in itertools.groupby('aBcD', key=lambda x: x.isupper()):
    reveal_type(grouper)
    reveal_type(members)

Running mypy at 1.6.1 without arguments or on any more recent version with --old-type-inference results in the expected output:

$ mypy demo.py --old-type-inference
demo.py:4: note: Revealed type is "builtins.bool"
demo.py:5: note: Revealed type is "typing.Iterator[builtins.str]"
Success: no issues found in 1 source file

However on more recent versions without --old-type-inference we get:

$ mypy demo.py 
demo.py:4: note: Revealed type is "Any"
demo.py:5: note: Revealed type is "typing.Iterator[builtins.str]"
Success: no issues found in 1 source file

Original case

In my original use-case, the grouper key was a tuple which I was spraying into a function call:

    for source, errors_group in itertools.groupby(errors, key=lambda x: x.source):
            messages = [x.message for x in errors_group]
            report_errors(*source, messages)

mypy was previously happy with that, however since the change to process the grouper key as Any I now get errors:

sr/comp/validation.py:113:13: error: Too many arguments for "report_errors"  [call-arg]

Your Environment

• Mypy version used: bisected to 93d4cb0a2ef1723ce92f39ae61fe6a0c010eb90b being the commit which introduced the change (from which I then tested --old-type-inference); I realise that commit doesn't introduce the new inference logic, though I haven't chased beyond that commit
• Mypy command-line flags: none required
• Mypy configuration options from mypy.ini (and other config files): none required
• Python version used: 3.10

Führe zunächst die Reproduktion in demo.py sowohl mit als auch ohne --old-type-inference aus und untersuche anschließend die Änderung rund um den Commit 93d4cb0a2ef1723ce92f39ae61fe6a0c010eb90b. Als erledigt gilt die Aufgabe, wenn der Schlüssel von itertools.groupby als builtins.bool offengelegt wird, während die Elemente typing.Iterator[builtins.str] bleiben, ohne den im ursprünglichen Fall gezeigten Aufruf mit Tupel-Schlüssel zu beeinträchtigen.