KT-9883 prohibit using spread operator for nullable value

#KT-9883 Fixed

compiler/testData/diagnostics/tests/varargs/NullableTypeForVarargArgument.kt

@@ -0,0 +1,44 @@
+// !DIAGNOSTICS:-UNUSED_PARAMETER
+
+// KT-9883 prohibit using spread operator for nullable value
+
+// FILE: A.java
+
+public class A {
+    public void foo(int x, String ... args) {}
+    public static String[] ar;
+}
+
+
+// FILE: 1.kt
+val args: Array<String>? = null
+
+fun bar(x: Int, vararg s: String) {}
+
+fun baz(s: String) {}
+
+fun f() {
+    A().foo(1, <!SPREAD_OF_NULLABLE!>*<!>args)
+    bar(2, <!SPREAD_OF_NULLABLE!>*<!><!TYPE_MISMATCH!>args<!>)
+    baz(<!NON_VARARG_SPREAD, SPREAD_OF_NULLABLE!>*<!>args)
+}
+
+fun g(args: Array<String>?) {
+
+    if (args != null) {
+        A().foo(1, *<!DEBUG_INFO_SMARTCAST!>args<!>)
+    }
+    A().foo(1, *A.ar)
+}
+
+class B {
+    var args: Array<String>? = null
+}
+
+fun h(b: B) {
+    if (b.args != null) {
+        A().foo(1, <!SPREAD_OF_NULLABLE!>*<!><!SMARTCAST_IMPOSSIBLE!>b.args<!>)
+    }
+}
+
+

compiler/testData/diagnostics/tests/varargs/NullableTypeForVarargArgument.txt

@@ -0,0 +1,27 @@
+package
+
+public val args: kotlin.Array<kotlin.String>? = null
+public fun bar(/*0*/ x: kotlin.Int, /*1*/ vararg s: kotlin.String /*kotlin.Array<out kotlin.String>*/): kotlin.Unit
+public fun baz(/*0*/ s: kotlin.String): kotlin.Unit
+public fun f(): kotlin.Unit
+public fun g(/*0*/ args: kotlin.Array<kotlin.String>?): kotlin.Unit
+public fun h(/*0*/ b: B): kotlin.Unit
+
+public open class A {
+    public constructor A()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open fun foo(/*0*/ x: kotlin.Int, /*1*/ vararg args: kotlin.String! /*kotlin.Array<(out) kotlin.String!>!*/): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+
+    // Static members
+    public final var ar: kotlin.Array<(out) kotlin.String!>!
+}
+
+public final class B {
+    public constructor B()
+    public final var args: kotlin.Array<kotlin.String>?
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}