OneOf Inhabitability#4564
Open
jbellenger wants to merge 5 commits into
Open
Conversation
|
@jbellenger is attempting to deploy a commit to the The GraphQL Foundation Team on Vercel. A member of the Team first needs to authorize it. |
jbellenger
force-pushed
the
jbellenger-oneof-inhabitability
branch
from
64e8899 to
bd3e1bf
Compare
benjie
reviewed
Feb 26, 2026
Member
benjie
left a comment
benjie
left a comment
There was a problem hiding this comment.
Great tests! (It's 10:30pm so I've not tried to review the code... 😅)
jbellenger
force-pushed
the
jbellenger-oneof-inhabitability
branch
from
bd3e1bf to
ba19546
Compare
benjie
added
the
spec RFC
martinbonnin
reviewed
Mar 9, 2026
Rework the circular references validation to detect input object types that cannot be provided a finite value. This covers: - Self-recursive OneOf types (e.g. input A @OneOf { a: A }) - Mixed OneOf/non-OneOf cycles with no escape path - Standard non-null circular references (existing behavior preserved) Rename algorithms to match spec terminology: - InputObjectHasUnbreakableCycle (was InputObjectCanBeProvidedAFiniteValue) - InputFieldTypeHasUnbreakableCycle (was FieldTypeCanBeProvidedAFiniteValue)
yaacovCR
force-pushed
the
jbellenger-oneof-inhabitability
branch
from
ba19546 to
c5a600f
Compare
- add memoization to improve validation performance - graceful handling of empty oneof defintions - add missing test coverage
Update error reporting for uninhabited cycles to match the previous implementation, which would report 1 error per distinct cycle. Also, update the errors to use the spec language "cannot be provided a finite value"
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
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.
This PR implements the validation described at graphql/graphql-spec#1211
More discussion is at the link above, but the core issue is around uninhabited OneOf types -- the property that a type can be defined in a way that a value cannot be generated for it.
The simplest example of an uninhabited type is this recursive OneOf:
While this type definition is currently valid by the rules of OneOf types and circular input types, it violates the spirit of the Circular References because it does not allow construction of a finite value.
This PR updates the existing cycle validation to consider OneOf types. I've tried to follow the existing conventions, though I'm also new here and might have missed something. Any feedback on style or substance is welcome.