Avoid erasure/preErasure issues around Any in transformIsInstanceOf #21647
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The testType Any is erased to Object, but the expr type Int isn't erased to Integer, so then it fails as Int !<: Object. We avoid the problem by feeding in AnyVal, leading to a (possibly elided) non-null test only.
sjrd
requested changes
Sep 30, 2024
Comment on lines
362
to
363
| if testType.isAny && expr.tpe.isPrimitiveValueType then | ||
| defn.AnyValType |
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Isn't that going to trigger with the same issue with any other type that erases to Object? Like ... AnyVal itself?
There's supposed to already be logic in transformIsInstanceOf to avoid a type test when expr.tpe <:< testType:
scala3/compiler/src/dotty/tools/dotc/transform/TypeTestsCasts.scala
Lines 259 to 261 in 9961e70
The problem is that it tests on erased types, instead of the original types. Addressing that at the root should be more robust, shouldn't it?
sjrd
reviewed
Nov 1, 2024
| class Test(): | ||
| def m1(xs: List[Boolean]) = for (x: Any) <- xs yield x | ||
| def m2(xs: List[Boolean]) = for (x: AnyVal) <- xs yield x | ||
| def m3(xs: List[Boolean]) = for (x: Matchable) <- xs yield x |
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A few more suggestions for tests:
def m1(xs: List[AnyVal]) = for (x: Any) <- xs yield x
def m1(xs: List[AnyVal]) = for (x: Matchable) <- xs yield x
def m1(xs: List[Matchable]) = for (x: Any) <- xs yield x
def m1(xs: List[Any]) = for (x: Any) <- xs yield x
sjrd
approved these changes
Nov 2, 2024
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The testType Any is erased to Object, but the expr type Int isn't erased
to Integer, so then it fails as Int
!<:Object. We avoid the problem byfeeding in AnyVal, leading to a (possibly elided) non-null test only.
Fixes #21544