Avoid erasure/preErasure issues around Any in transformIsInstanceOf

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.
scala · Sep 25, 2024 · d02d4b8 · d02d4b8
1 parent 4293a45
commit d02d4b8
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diff --git a/compiler/src/dotty/tools/dotc/transform/TypeTestsCasts.scala b/compiler/src/dotty/tools/dotc/transform/TypeTestsCasts.scala
@@ -358,7 +358,11 @@ object TypeTestsCasts {
                 report.error(em"$untestable cannot be used in runtime type tests", tree.srcPos)
                 constant(expr, Literal(Constant(false)))
               case _ =>
-                val erasedTestType = erasure(testType)
+                val erasedTestType =
+                  if testType.isAny && expr.tpe.isPrimitiveValueType then
+                    defn.AnyValType
+                  else
+                    erasure(testType)
                 transformIsInstanceOf(expr, erasedTestType, erasedTestType, flagUnrelated)
         }
 

diff --git a/tests/pos/i21544.scala b/tests/pos/i21544.scala
@@ -0,0 +1,2 @@
+class Test():
+  def m1(xs: List[Boolean]) = for (x: Any) <- xs yield x
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		class Test():
		def m1(xs: List[Boolean]) = for (x: Any) <- xs yield x