fix: Add loc getter on fragment documents for graphql-tag inter-compatibility

[kitten]

Summary

Unfortunately graphql-tag has several quirks, including concatenating all interpolations' source bodies and parsing them all as a whole. While it does so, it blindly uses document.loc without checking whether this property is undefined, despite it being optional.

This leads to an incompatibility since it's purposefully left out in graphql.web. However, during a gradual migration it's conceivable that gql.tada's graphql() fragments will be interpolated into graphql-tag's tag functions.

While this isn't recommended, since it's also possible to "blanket-migrate" from graphql-tag's gql function to graphql() functions from gql.tada, this would likely require codemods, so a partial migration isn't unlikely.

To solve this, we now add a loc getter, which creates a document, similar to how graphql-tag would expect it recursively. It also deduplicates documents to avoid graphql-tag receiving invalid input when a fragment is used multiple times.

Set of changes

• Add concatLocSources utility
• Add faux-loc getter on documents for fragment outputs

[changeset-bot]

🦋 Changeset detected

Latest commit: 8a29714

The changes in this PR will be included in the next version bump.

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR