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This patch removes the following defaulting of type variables in type and data families: - type variables of kind RuntimeRep defaulting to LiftedRep - type variables of kind Levity defaulting to Lifted - type variables of kind Multiplicity defaulting to Many It does this by passing "defaulting options" to the `defaultTyVars` function; when calling from `tcTyFamInstEqnGuts` or `tcDataFamInstHeader` we pass options that avoid defaulting. This avoids wildcards being defaulted, which caused type families to unexpectedly fail to reduce. Note that kind defaulting, applicable only with -XNoPolyKinds, is not changed by this patch. Fixes #17536 ------------------------- Metric Increase: T12227 -------------------------
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