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GeezerVison is showing github.com — gh-151128: Improve SyntaxError message for cross language keywords by zang-langyan · Pull Request #151129 · python/cpython

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zang-langyan commented Jun 9, 2026

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zang-langyan added 2 commits

June 9, 2026 15:58


          pythongh-151128 Improve SyntaxError message for match

ba55af2


          suggestion does not compute full match distance

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Jun 9, 2026

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Jun 9, 2026

Improve SyntaxError message for match #151128

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serhiy-storchaka commented Jun 9, 2026

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I do not think that it is needed to add 'switch' to keywords.

Even if we only add one special case, it is worth to write more general code which will allow to add more keywords in future. See #146407 as example.

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zang-langyan commented Jun 9, 2026

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I do not think that it is needed to add 'switch' to keywords.

Even if we only add one special case, it is worth to write more general code which will allow to add more keywords in future. See #146407 as example.

Thank you for the reference, it is really a good example. I will look into it.

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          add cross language keyword hints list as a general implementation

3a2926f

zang-langyan requested review from lysnikolaou and pablogsal as code owners

June 9, 2026 12:59

zang-langyan changed the title ~~gh-151128: Improve SyntaxError message for match~~ gh-151128: Improve SyntaxError message for cross language keywords

Jun 9, 2026


          trim trailing whitespace

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Jun 10, 2026

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Lib/traceback.py Outdated

Comment on lines +1890 to +1891

		hint = _CROSS_LANGUAGE_KEYWORD_HINTS.get(wrong_name)
		return hint

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serhiy-storchaka reviewed

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You can split this on two features -- for keywords and for operators.

Anyway, it needs a NEWS entry, a What's New entry, and tests.

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Grammar/python.gram Outdated

		\| a=expression ':=' expression {
		RAISE_SYNTAX_ERROR_KNOWN_LOCATION(
		a, "cannot use assignment expressions with %s", _PyPegen_get_expr_name(a)) }
		\| a=expression '&''&' b=expression {

serhiy-storchaka Jun 10, 2026

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Nice. This is actually a different feature. You can even open a separate issue and PR for this (if there is no already open). Anyway, this is a nice improvement.

I suggest to add also cases for <> ("not equal" in Pascal and Python 2), "=<", "=>" and "=!" (typo in "<=", ">=" and "!="), "===" ("is" in JavaScript and PHP).

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IvyXu420 Jun 11, 2026

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Actually there is already a PR for improving SyntaxError message of && and ||: #150906

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zang-langyan Jun 11, 2026

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Thank you for review, great suggestion, I will add those~

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serhiy-storchaka Jun 11, 2026

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Then let's focus on keywords in this PR.

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IvyXu420 reviewed

Jun 11, 2026

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Lib/traceback.py Outdated

		suggestion = _suggestions._generate_suggestions(keyword.kwlist + keyword.softkwlist, wrong_name)
		if suggestion:
		matches.append(suggestion)
		matches.extend(difflib.get_close_matches(wrong_name, keyword.kwlist, n=max_matches, cutoff=0.5))

IvyXu420 Jun 11, 2026

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Suggested change

	matches.extend(difflib.get_close_matches(wrong_name, keyword.kwlist, n=max_matches, cutoff=0.5))
	matches.extend(difflib.get_close_matches(wrong_name, keyword.kwlist+keyword.softkwlist, n=max_matches, cutoff=0.5))

Maybe we should add softkwlist here too?

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serhiy-storchaka mentioned this pull request

Jun 11, 2026

gh-146495: Improve SyntaxError message for && and || operators #150906

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Aniketsy mentioned this pull request

Jun 11, 2026

Improve SyntaxError suggestions for common operator typos and cross-language mistakes #151303

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          focus on keyword suggestion

f3cdecc

zang-langyan requested a review from serhiy-storchaka

June 11, 2026 16:23


          remove trailing whitespace

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Jun 11, 2026

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Could you please add also tests for soft keywords? And document this change in the NEWS entry.

Why aliases for None were removed? Were there issues with them?

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zang-langyan commented Jun 11, 2026 •

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Could you please add also tests for soft keywords? And document this change in the NEWS entry.

Why aliases for None were removed? Were there issues with them?

Sure, I will add the tests for soft keywords.

I removed the aliases for None because I realized that names like Null, nil, etc. don't work well for keyword syntax detection. I can't think of a situation where these tokens would be correctly identified as keywords. Any suggestions?

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          add test for soft keywords

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serhiy-storchaka commented Jun 11, 2026

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You are right. Maybe they can be handled where NameError is handed.

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serhiy-storchaka reviewed

Jun 11, 2026

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Lib/test/test_traceback.py Resolved

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Lib/traceback.py Resolved

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Lib/traceback.py

		max_matches = 3
		matches = []

		hint = _get_cross_language_keyword_hint(wrong_name)

edvilme Jun 11, 2026

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Suggested change

	hint = _get_cross_language_keyword_hint(wrong_name)
	hint = _CROSS_LANGUAGE_KEYWORD_HINTS.get(wrong_name)

If it is only used once, and is marked as a "private" method, I would suggest calling the body directly

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zang-langyan Jun 12, 2026

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Not sure about this. I still think a get method looks nicer..

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zang-langyan added 2 commits

June 12, 2026 11:36


          add tests for keyword lazy and add void as another crosslang case

9e13d74


          remove whitespace

896dd06

zang-langyan requested a review from serhiy-storchaka

June 15, 2026 17:33

serhiy-storchaka approved these changes

Jun 15, 2026

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LGTM. 👍

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bedevere-app Bot added awaiting merge and removed awaiting review labels

Jun 15, 2026

serhiy-storchaka merged commit 5ea1e90 into python:main

Jun 15, 2026

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bedevere-app Bot removed the awaiting merge label

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philthompson10 pushed a commit to philthompson10/cpython that referenced this pull request

Jun 17, 2026


          pythongh-151128: Improve SyntaxError message for cross language keywo…

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…rds (pythonGH-151129)

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zang-langyan commented Jun 9, 2026

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zang-langyan commented Jun 11, 2026 •

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