Intersection types are no more allowed in signatures #KT-10244 Fixed

compiler/testData/diagnostics/tests/implicitIntersection.kt

@@ -0,0 +1,23 @@
+// See KT-10244: no intersection types in signatures
+open class B
+interface A
+interface C
+
+// Error!
+fun <!IMPLICIT_INTERSECTION_TYPE!>foo<!>(b: B) = if (b is A && b is C) b else null
+
+// Ok: given explicitly
+fun gav(b: B): A? = if (b is A && b is C) <!DEBUG_INFO_SMARTCAST!>b<!> else null
+
+class My(b: B) {
+    // Error!
+    val <!IMPLICIT_INTERSECTION_TYPE!>x<!> = if (b is A && b is C) b else null
+    // Ok: given explicitly
+    val y: C? = if (b is A && b is C) <!DEBUG_INFO_SMARTCAST!>b<!> else null
+}
+
+fun bar(b: B): String {
+    // Ok: local variable
+    val tmp = if (b is A && b is C) b else null
+    return tmp.toString()
+}