types overlap only if all type args match #9452
Merged
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
gvanrossum
reviewed
Sep 17, 2020
Comment on lines
339
to
341
| # Or, to use a more concrete example, List[Union[A, B]] and List[Union[B, C]] | ||
| # would be considered partially overlapping since it's possible for both lists | ||
| # to contain only instances of B at runtime. |
Member
There was a problem hiding this comment.
Looking at this example I am wondering if the original behavior wasn't intentional?
Member
Author
There was a problem hiding this comment.
The example only has a single type argument; I think the case with multiple args was just not considered.
Collaborator
There was a problem hiding this comment.
I stumbled a little on this too, unions are dealt with by the recursive call, about a hundred lines earlier in the function
JukkaL
approved these changes
Sep 18, 2020
Collaborator
JukkaL
left a comment
JukkaL
left a comment
There was a problem hiding this comment.
Looks this was an oversight in the original implementation.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
4 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Outdated suggestions cannot be applied.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.
Fixes #9451
Description
Previously, generic types were considered overlapping as soon as the first type argument matched. Now, we check all type arguments.
Test Plan
The new test failed before my change and now passes.