Merge pull request #73 from scala/backport-lts-3.3-21647

Backport "Avoid erasure/preErasure issues around Any in transformIsInstanceOf" to 3.3 LTS

Author: tgodzik

compiler/src/dotty/tools/dotc/transform/TypeTestsCasts.scala

@@ -250,7 +250,8 @@ object TypeTestsCasts {
             else foundClasses.exists(check)
           end checkSensical
 
-          if (expr.tpe <:< testType) && inMatch then
+          val tp = if expr.tpe.isPrimitiveValueType then defn.boxedType(expr.tpe) else expr.tpe
+          if tp <:< testType && inMatch then
             if expr.tpe.isNotNull then constant(expr, Literal(Constant(true)))
             else expr.testNotNull
           else {

tests/pos/i21544.scala

@@ -0,0 +1,13 @@
+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
+
+  def v1(xs: List[AnyVal])    = for (x: Any) <- xs yield x
+  def v2(xs: List[AnyVal])    = for (x: AnyVal) <- xs yield x
+  def v3(xs: List[AnyVal])    = for (x: Matchable) <- xs yield x
+
+  def t1(xs: List[Matchable]) = for (x: Any) <- xs yield x
+  def t2(xs: List[Matchable]) = for (x: Matchable) <- xs yield x
+
+  def a1(xs: List[Any])       = for (x: Any) <- xs yield x