Use wildcard type instead of whitebox cast in IsoFields#1574
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mbovel wants to merge 1 commit intooptics-dev:masterfrom
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Use wildcard type instead of whitebox cast in IsoFields#1574mbovel wants to merge 1 commit intooptics-dev:masterfrom
mbovel wants to merge 1 commit intooptics-dev:masterfrom
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Replace the `whitebox` cast (`asInstanceOf[Expr[Iso[S, Tuple]]]`) with a proper wildcard return type using `PIso[S, S, ? <: Tuple, ? <: Tuple]`. Since `IsoFields.apply` is a `transparent inline` method, the compiler still infers the precise tuple type at call sites. This avoids the unsafe cast and prepares for potential stricter macro type checking in future Scala versions. The motivation is to prepare for future stricter checks in the Scala 3 compiler. The current implementation exploits a missing check to generate an unsound cast. Note: we use `PIso` (a trait) directly instead of the `Iso` type alias (defined as `type Iso[S, A] = PIso[S, S, A, A]`) because Scala 3 cannot reduce higher-kinded type aliases applied to wildcard arguments. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Replace the
whiteboxcast (asInstanceOf[Expr[Iso[S, Tuple]]]) with a wildcard return type usingPIso[S, S, ? <: Tuple, ? <: Tuple].Since
IsoFields.applyis atransparent inlinemethod, the compiler still infers the precise tuple type at call sites. This avoids the unsafe cast and prepares for potential stricter macro type checking in future Scala versions.The motivation is to prepare for future stricter checks in the Scala 3 compiler (scala/scala3#25756). The current implementation exploits a missing check to generate an unsound cast.
Note: we use
PIso(a trait) directly instead of theIsotype alias (defined astype Iso[S, A] = PIso[S, S, A, A]) because Scala 3 cannot reduce higher-kinded type aliases applied to wildcard arguments. Is that acceptable to usePIsoinstead ofIso?