Adjust function literal return type inference to avoid spurious null #4210
Conversation
This file contains 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
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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Outdated suggestions cannot be applied.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.
See dart-lang/sdk#59669 where this topic came up. Thanks to @chiholai-sanasofthk for spotting this issue!
This PR changes one item in the list of actions taken during function literal return type inference: A
return;statement only addsNullto the return type in cases where the given function literal is a non-generator.With the current version,
Nullis added to the return type also in cases like() sync* { yield 1; return; }such that this function literal gets the inferred return typeIterable<int?>. This is an unnecessary loss of typing precision because null is never actually added to the returned iterable. With this update, the inferred return type isIterable<int>.