Remove dead code from clinic.py

[erlend-aasland]

There's a bit of unused code in clinic.py. For example, the code that manipulated second_pass_replacements was removed in 2015 (commit 0759f84, gh-67688 (bpo-23500)), but the variable and a branch depending on it still persists.

Suggesting to remove all unused code in order to make clinic more readable and maintainable.

Linked PRs

• gh-104146: Remove unused 'second_pass_replacements' from clinic.py #104147
• gh-104146: Remove unused var 'parser_body_declarations' from clinic.py #104214
• gh-104146: Remove unused vars from Argument Clinic #104627
• gh-104146: Purge dead code from Argument Clinic #104680
• gh-104146: Remove unused attr 'parameter_indent' from clinic.DLParser #106358
• gh-104146: Remove dead code from Argument Clinic #107555
• gh-104146: Argument clinic: remove unused methods and variables #107608
• gh-104146: Argument clinic: Remove dead code flagged by mypy's truthy-bool check #107627
• gh-104146: Argument clinic: remove dead code highlighted by the vulture tool #107632
• gh-104146: Purge CConverter.parse_by_reference from Argument Clinic #119162

[erlend-aasland]

Encountered more unused vars in DSLParser.directive_class; reopening.

[AlexWaygood]

Running pyflakes on Tools/clinic finds a few more yet:

Tools/clinic/clinic.py:551:5: local variable 'result' is assigned to but never used
Tools/clinic/clinic.py:1341:9: local variable 'groups' is assigned to but never used
Tools/clinic/clinic.py:1431:9: local variable 'default_return_converter' is assigned to but never used
Tools/clinic/clinic.py:1529:9: local variable 'ignore_self' is assigned to but never used
Tools/clinic/clinic.py:1809:21: local variable 'input_checksum' is assigned to but never used
Tools/clinic/clinic.py:4224:9: local variable 'new' is assigned to but never used

All except maybe the last one look as though they're true positives to me, from skimming the code.

[erlend-aasland]

Running pyflakes on Tools/clinic finds a few more yet:

Let's leave this open, but I suggest we remove them when we encounter issues with them. For example, in gh-104627 I removed variables that created havoc when I added type annotations for the surrounding code.

[erlend-aasland]

OTOH, there's no harm in removing them right away. After all, the grand plan is to improve the readability and maintainability of Argument Clinic. Unused code is clutter, and it makes it harder to understand what's happening.