Compute statement hashability from underlying query fragment #245
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We currently depend directly on the hashability of `Statement` in the various fetch property wrappers, but this conformance has been found to be problematic and so we should remove it. We can make this change today, though, before removing it, by computing the hashability of a statement from its query fragment data.
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We made `Statement: Hashable` for convenience in holding onto statements in a shared key for SQLiteData, but that isn't really necessary, since we can always call out to the underlying query fragment to get a hashable value. This conformance unfortunately can cause bugs, including `==` resolving to the equality operator when a query operator was expected. Another bug is that `@Table @Selection` types conform to `Statement`, and this equatable implementation was preferred over the default synthesized version, making `Table` values equatable strictly by the underlying query, which meant `@Ephemeral` fields weren't taken into account at all. With 0.20.0, all `@Table` applications introduced a `Statement` conformance, and so this issue becomes much more widespread. While this change can break SQLiteData if someone upgrades StructuredQueries before upgrading SQLiteData with the changes from pointfreeco/sqlite-data#245.
stephencelis
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Oct 8, 2025
mbrandonw
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Oct 8, 2025
stephencelis
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Oct 8, 2025
* `Statement` shouldn't inherit from `Hashable` We made `Statement: Hashable` for convenience in holding onto statements in a shared key for SQLiteData, but that isn't really necessary, since we can always call out to the underlying query fragment to get a hashable value. This conformance unfortunately can cause bugs, including `==` resolving to the equality operator when a query operator was expected. Another bug is that `@Table @Selection` types conform to `Statement`, and this equatable implementation was preferred over the default synthesized version, making `Table` values equatable strictly by the underlying query, which meant `@Ephemeral` fields weren't taken into account at all. With 0.20.0, all `@Table` applications introduced a `Statement` conformance, and so this issue becomes much more widespread. While this change can break SQLiteData if someone upgrades StructuredQueries before upgrading SQLiteData with the changes from pointfreeco/sqlite-data#245. * fix
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We currently depend directly on the hashability of
Statementin the various fetch property wrappers, but this conformance has been found to be problematic and so we should remove it. We can make this change today, though, before removing it, by computing the hashability of a statement from its query fragment data.