Module 'trace' has no attribute 'modname' while trying to debug in PyCharm (Python 3.6)

Question

I have Python 3.6rc1 installed from the official "pkg" bundle for Mac OS. Now, every time I'm using a "debug" run configuration in PyCharm (does not depend on a particular script), I'm getting a huge stack trace with the following error messages (thrown multiple times in a row):

Traceback (most recent call last):
  File "/Applications/PyCharm.app/Contents/helpers/pydev/_pydevd_bundle/pydevd_signature.py", line 88, in create_signature
    filename, modulename, funcname = self.file_module_function_of(frame)
  File "/Applications/PyCharm.app/Contents/helpers/pydev/_pydevd_bundle/pydevd_signature.py", line 102, in file_module_function_of
    modulename = trace.modname(filename)
AttributeError: module 'trace' has no attribute 'modname'

Using the currently latest PyCharm 2016.3. Note that I can debug using Python 2.7 or 3.5 using the same PyCharm instance without any problems.

Has anyone experienced anything like this? Is there a workaround?

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^{Posting on SO since I'm not completely sure this is actually a bug or I've misconfigured something; plus, I know that PyCharm team checks the pycharm tag here; and, it would be easier for others to find this topic here as opposed to on the PyCharm's bug tracker.}

Answer 1

There is actually a bug in the PyCharm's PyDev.Debugger, it uses the trace.modname which does not exist since Python 3.2:

def file_module_function_of(self, frame): #this code is take from trace module and fixed to work with new-style classes
    code = frame.f_code
    filename = code.co_filename
    if filename:
        modulename = trace.modname(filename)  # < HERE
    else:
        modulename = None
    # ...

Now, this particular code would only be executed if the debugger is started with the --save-signatures command-line option which is enabled by the "Collect run-time types information for code insight" Python debugger setting:

Turn the setting off and the error would go away.