Summary

When an AttributeError on a builtin type (list, str, dict) has no
Levenshtein-based suggestion, check a static table of common method names
from other languages.

Before:

>>> [1, 2, 3].push(4)
AttributeError: 'list' object has no attribute 'push'

After:

>>> [1, 2, 3].push(4)
AttributeError: 'list' object has no attribute 'push'. Did you mean '.append' instead of '.push'?

Discourse discussion

Discussed at https://discuss.python.org/t/106632 (420 views, 25 likes, 15 posts, 3 core devs).

Design decisions from the thread:

• Flat table per @pf_moore (post 14, 4 likes):

  "the table can simply map the method name and object type onto a suggestion. So add on a list is mapped straight to 'did you mean to use a set?' No need to check whether add is a set method - you know it is already."

• list.add() suggests set, not append per @Storchaka (post 8):

  "It can also mean that you passed a list instead of set. Changing 'add' to 'append' will not fix the error, it will introduce yet one error."

  Reinforced by @tjreedy (post 12):

  "When a method exists for another, related, Python class, I think it better to suggest the other class rather than assume a foreign language match."

• Scope guardrails per @dr_carlos (post 3): only add entries backed by real confusion evidence, not just because methods are similar.

• Static table for builtins only (Option 1) - community consensus. 11 entries covering JavaScript, Java, C#, and Ruby.

Verification

Before (system Python 3.13, no cross-language hints):

>>> [1, 2, 3].push(4)
AttributeError: 'list' object has no attribute 'push'

>>> 'hello'.toUpperCase()
AttributeError: 'str' object has no attribute 'toUpperCase'

>>> {}.keySet()
AttributeError: 'dict' object has no attribute 'keySet'

>>> [].add(1)
AttributeError: 'list' object has no attribute 'add'

After (this PR):

>>> [1, 2, 3].push(4)
AttributeError: 'list' object has no attribute 'push'. Did you mean '.append' instead of '.push'?

>>> 'hello'.toUpperCase()
AttributeError: 'str' object has no attribute 'toUpperCase'. Did you mean '.upper' instead of '.toUpperCase'?

>>> {}.keySet()
AttributeError: 'dict' object has no attribute 'keySet'. Did you mean '.keys' instead of '.keySet'?

>>> [].add(1)
AttributeError: 'list' object has no attribute 'add'. Did you mean to use a set? Sets have an .add() method

Levenshtein still takes priority (trim->strip, indexOf->index already work and are not in the table). Only exact builtin types are matched - subclasses are not affected.

Changes

• Lib/traceback.py: Added _CROSS_LANGUAGE_HINTS dict (11 entries), _get_cross_language_hint() function, and a 4-line fallback hook in TracebackException.__init__ that runs only when Levenshtein found nothing.
• Lib/test/test_traceback.py: 15 test cases covering all entries, priority ordering, unknown attrs, and subclass exclusion.
• Misc/NEWS.d/: NEWS entry.

Evidence

Fixes #146406

• Issue: Add cross-language method suggestions for builtin AttributeError #146406