JS: refactor generation of functions with optional parameters. Fix #KT-7302, #KT-13888

js/js.translator/testData/box/defaultArguments/complexExpressionAsOverriddenDefaultArgument.kt

@@ -0,0 +1,42 @@
+// http://youtrack.jetbrains.com/issue/KT-4879
+// JS: extra side effect when use when in default arguments
+
+package foo
+
+var global: String = ""
+
+fun bar(): Int {
+    global += ":bar:"
+    return 100
+}
+
+fun baz() = 1
+
+open class A {
+    open fun foo(a: Int = when (baz()) { 1 -> bar(); else -> 0 }): Int = a + 1
+
+    open fun bar0(x: String = try { global } finally {}): String {
+        return "bar: ${x}"
+    }
+}
+
+class B : A() {
+    override fun foo(a: Int) = a + 2
+
+    override fun bar0(x: String) = "B.bar: $x"
+}
+
+fun box(): String {
+    global = ""
+    val b = B()
+    assertEquals(102, b.foo(100))
+    assertEquals("", global)
+
+    assertEquals(102, b.foo())
+    assertEquals(":bar:", global)
+
+    assertEquals("B.bar: q", b.bar0("q"))
+    assertEquals("B.bar: :bar:", b.bar0())
+
+    return "OK"
+}