Fix #7048: Check for splice stability #8097
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nicolasstucki
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| { | ||
| val s = '{Option.empty[${T}]} | ||
| val r = '{identity($s)} // works | ||
| val r2 = '{identity(${s: Expr[Option[T]]})} // error // error |
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It's not obvious why this is not accepted by the check.
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32 | val r2 = '{identity[Option[T]](${s: Expr[Option[T]]})} // error // error
| ^^^^^^^^^^^^^^^^^^^^^
| (Test.this.given_Type_T : => quoted.Type[Test.this.T]) is not stable
All these can be fixed by making the given stable
val getT: Type[T] = T // need this to avoid getting `null`
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Added an extra test for it
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Why it has to be stable?
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Type splices require a stable prefix to be correctly encoded. It also avoids having to deal with side effects in the transformation performed in ReifyQuotes. Most code receives the quoted type as a parameter and hence is stable.
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It's a restriction in TASTy? This is unprecedented in Scala, as usually only the path in types needs to be stable.
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This is a path in a type. A type that is inferred and then healed.
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