Simple and reliable method to retrieve qualified name of the current function

Question

I'd like to retrieve qualified name like function or class property __qualname__ for the current function. inspect.stack() provides only simple unqualified name.

So I'm looking for a trick to calculate qualified name from available introspection info. I recoursed to trial-and-error in absence of python's internal representation knowledge and still could not figure the method. Python naturally calculates qualified names, so all required information are already available but I don't know where to find it.

I searched on the stackoverflow site and had found few solutions each incurring a drawback.

Check frame's locals

The method was proposed by @Aran-Fey in #42322828. Just scan stack locals for the first occurred __qualname__

def retrieveQualifiedName():
    f = inspect.currentframe()
    while f:
        if '__qualname__' in f.f_locals:
            return f.f_locals['__qualname__']
        f = f.f_back
    return None

It works good for classes nested in other classes directly but fails when there is a function in between.

good for

class A:
    class B: pass

bad for

class A:
    def a(self):
        class B: pass
        return B()

Offload all work to the 'executing' library

@Alex Hall suggested in #12190238 to use third-party introspection library executing

import executing
def retrieveQualifiedName():
    f = inspect.currentframe().f_back.f_back
    return executing.Source.executing(f).code_qualname()

The library calculates qualified name pretty reliably, but two things make me search for another solution.

First using third-party dependency complicates support. I could not just write a simple python script, I need to use full project definition and build artefacts. I would like to avoid it if possible.

Second the executing library parses source code to infer qualified name causing excess processing. I would like to extract qualified name from information already available to the interpreter.