Give useful message if can't infer TypeVar-based type for attribute #3651
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Require a type annotation if the inferred attribute type includes a type variable with values. Fix #2697 by giving a better error message. Fixing type inference would be much more complicated. This partial fix should be fine as the issue seems to arise pretty rarely. Mypy processes methods of a generic class that has a type variable with values by type checking the methods multiple times, once for each type variable value. This implementation detects if different type checking passes infer a different type for an attribute. The extra data structure for storing inferred attibute types helps with with fine-grained incremental checking.
ilevkivskyi
approved these changes
Jul 18, 2017
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Require a type annotation if the inferred attribute type includes a
type variable with values.
Fix #2697 by giving a better error message. Fixing type inference
would be much more complicated. This partial fix should be fine as the
issue seems to arise pretty rarely.
Mypy processes methods of a generic class that has a type variable
with values by type checking the methods multiple times, once for each
type variable value. This implementation detects if different type
checking passes infer a different type for an attribute.
The extra data structure for storing inferred attibute types helps
with with fine-grained incremental checking.