python / python/mypy

Error context for string interpolation may be wrong

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#7,528 1 comment 0 reactions 0 assignees View on GitHub

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priority-0-high topic-error-reporting topic-usability
Dominant language
Python
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Description

If there are multiple replacements like '%s, %s' % (one, other), many errors (e.g. wrong replacement type) are reported with the tuple expression as the location. It would be better to set specific item as the error context as the current way can be quite misleading if one uses, --show-column-numbers, or --pretty, or one has a multi-line interpolation.

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  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the multi-replacement interpolation case and compare the reported location with and without --show-column-numbers and --pretty, including a multi-line expression. Trace the interpolation error-reporting path and add coverage showing that each replacement error points to its specific item rather than the tuple expression.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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