stdlib: turn singleton type var warning into error #8556
Merged
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
Singleton type variables in an union type do not make sense from
Dialyzer's point of view. The following example is ill-typed:
```erlang
-spec run_test(Opts) -> term()
when Opts :: {join_specs, Bool} | {test, Bool}.
```
But this cannot be ever checked by Dialyzer as the type variable `Bool`
is in a union and used a single time. Dialyzer cannot check that the
`Bool` set of values passed to `join_specs` will be the same set of
values as the ones passed in the `Bool` type variable in the `test`
branch. Thus, an error follows.
kikofernandez
added
team:VM
CT Test Results 2 files 95 suites 35m 29s ⏱️ Results for commit 68665cc. ♻️ This comment has been updated with latest results. To speed up review, make sure that you have read Contributing to Erlang/OTP and that all checks pass. See the TESTING and DEVELOPMENT HowTo guides for details about how to run test locally. Artifacts// Erlang/OTP Github Action Bot |
bjorng
approved these changes
Jun 17, 2024
kikofernandez
deleted the
kiko/stdlib/turn-warning-singleton-typevar-into-error/OTP-19125
branch
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Outdated suggestions cannot be applied.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.
Singleton type variables in an union type do not make sense from Dialyzer's point of view. The following example is ill-typed:
But this cannot be ever checked by Dialyzer as the type variable
Boolis in a union and used a single time. Dialyzer cannot check that theBoolset of values passed tojoin_specswill be the same set of values as the ones passed in theBooltype variable in thetestbranch. Thus, an error follows.