Fix isInstanceOf[Array[?]] returning true on non-Array #12103
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Before this commit, the `MultiArrayOf(elem, ndims)` extractor used to
strip wildcards from the element type, this was surprising since it does
not match what the `ArrayOf(elem)` extractor does, and lead to a bug in
`TypeTestCasts.interceptTypeApply` which contains the following code:
case defn.MultiArrayOf(elem, ndims) if isGenericArrayElement(elem, isScala2 = false) =>
`isGenericArrayElement` returns false for `Any` but true for
`_ >: Nothing <: Any`, so the stripped wildcard means that this case was
skipped, resulting in:
x.isInstanceOf[Array[?]]
being erased to:
x.isInstanceOf[Object]
instead of:
scala.runtime.ScalaRunTime.isArray(x, 1)
Fixed by tweaking `MultiArrayOf` to keep any final wildcard around like
`ArrayOf` does.
|
Milestoned to 3.0.0-RC3 since a bug in isInstanceOf seems pretty critical to me. |
sjrd
requested changes
Apr 15, 2021
| val str: Any = "" | ||
| assert(!str.isInstanceOf[Array[?]]) | ||
| assert(!str.isInstanceOf[Array[Array[?]]]) | ||
| assert(!str.isInstanceOf[Array[? <: Array[?]]]) |
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Also add positive tests? I.e., tests for which isInstanceOf returns true.
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That file already checks case x: Array[_] in various situations
sjrd
approved these changes
Apr 15, 2021
smarter
added
the
backport:accepted
smarter
added
backport:done
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Before this commit, the
MultiArrayOf(elem, ndims)extractor used tostrip wildcards from the element type, this was surprising since it does
not match what the
ArrayOf(elem)extractor does, and lead to a bug inTypeTestCasts.interceptTypeApplywhich contains the following code:isGenericArrayElementreturns false forAnybut true for_ >: Nothing <: Any, so the stripped wildcard means that this case wasskipped, resulting in:
being erased to:
instead of:
Fixed by tweaking
MultiArrayOfto keep any final wildcard around likeArrayOfdoes.