--experimental-string-processing crash on string + % {

[JelleZijlstra]

% cat legacy.py                                   

def _legacy_listen_examples():
    text += (
        "    \"listen for the '%(event_name)s' event\"\n"
        "\n    # ... (event logic logic logic) ...\n"
        % {
            "since": since,
        }
    )
% black --experimental-string-processing legacy.py
error: cannot format legacy.py: Apparently, old parentheses do NOT exist?!
Oh no! 💥 💔 💥
1 file failed to reformat.

Minified from a file in sqlalchemy that we originally found this crash on.

The crash is in the StringParenWrapper class in trans.py, which apparently doesn't know how to handle the parentheses enclosing the string + % {. I spent some time looking at it but I'm not sure what the best solution is.

[ichard26]

What even... apparently I opened the label selection menu at the worse time ever that I cleared the labels... AHHH

[JelleZijlstra]

@bbugyi200 would you still be interested in fixing this one? Right now it's the only --experimental-string-processing crash we're aware of.

[bbugyi200]

@JelleZijlstra Thanks for tagging me. The follownig PR should fix this crash: #2283

[JelleZijlstra]

Thank you! I really appreciate you helping out with all of these issues.