SCL-23859: show kind mismatch error for existential types

Author: Alex1005a

scala/scala-impl/src/org/jetbrains/plugins/scala/annotator/element/ScParameterizedTypeElementAnnotator.scala

@@ -139,11 +139,10 @@ object ScParameterizedTypeElementAnnotator extends ElementAnnotator[ScParameteri
       (arg, param) <- args.zip(params)
       argTy        <- getType(arg).toOption
       range        = if (isForContextBound) annotationRange else arg.getTextRange
-      if !argTy.is[ScExistentialArgument, ScExistentialType] &&
-        !argIsDesignatedToTypeVariable(arg) &&
+      if !argIsDesignatedToTypeVariable(arg) &&
         !KindProjectorUtil.syntaxIdsFor(arg).contains(arg.getText)
     } {
-      checkBounds(range, argTy, param, substitute)
+      if(!argTy.is[ScExistentialArgument, ScExistentialType]) checkBounds(range, argTy, param, substitute)
       checkHigherKindedType(range, argTy, param, substitute)
     }
   }

scala/scala-impl/test/org/jetbrains/plugins/scala/annotator/ScGenericCallAnnotatorTest.scala

@@ -60,6 +60,10 @@ class ScGenericCallAnnotatorTest extends SimpleTestCase {
     assertMessages(messages("testHk[HkArg]"))(
       Error("HkArg", "Type constructor HkArg does not conform to CC[X >: B <: B, _]")
     )
+
+    assertMessages(messages("class Test[X, Y]; testHk[Test[_, _]]"))(
+      Error("Test[_, _]", "Expected type constructor CC[X >: B <: B, _]")
+    )
   }
 
   def testTypeConstructorParameter(): Unit = {

scala/scala-impl/test/org/jetbrains/plugins/scala/annotator/ScParameterizedTypeElementAnnotatorTest.scala

@@ -227,6 +227,19 @@ class ScParameterizedTypeElementAnnotatorTest_scala_2 extends ScParameterizedTyp
     ))
   }
 
+  def testExistentialTypeKindMismatch(): Unit = {
+    assertMessages(messages(
+      """
+        |class Option[A]
+        |class TestClass[F[_]]
+        |
+        |def test: TestClass[Option[_]] = ???
+        |""".stripMargin
+    ))(
+      Error("Option[_]", "Expected type constructor F[_]")
+    )
+  }
+
   def testUnresolved(): Unit = {
     assertNothing(messages(
       """