Fix inline class coercion in default parameter values

#KT-27358

compiler/testData/codegen/box/inlineClasses/defaultConstructorParameterValuesOfInlineClassType.kt

@@ -0,0 +1,15 @@
+// !LANGUAGE: +InlineClasses
+// IGNORE_BACKEND: JVM_IR
+
+inline class Z(val z: Int)
+
+class Test(val z: Z = Z(42)) {
+    fun test() = z.z
+}
+
+fun box(): String {
+    if (Test().test() != 42) throw AssertionError()
+    if (Test(Z(123)).test() != 123) throw AssertionError()
+
+    return "OK"
+}

compiler/testData/codegen/box/inlineClasses/defaultInterfaceFunParameterValuesOfInlineClassType.kt

@@ -0,0 +1,24 @@
+// !LANGUAGE: +InlineClasses
+// IGNORE_BACKEND: JVM_IR
+
+inline class Z(val z: Int)
+
+interface ITest {
+    fun testDefault(z: Z = Z(42)) = z.z
+
+    fun testOverridden(z: Z = Z(42)): Int
+}
+
+class Test : ITest {
+    override fun testOverridden(z: Z) = z.z
+}
+
+fun box(): String {
+    if (Test().testDefault() != 42) throw AssertionError()
+    if (Test().testDefault(Z(123)) != 123) throw AssertionError()
+
+    if (Test().testOverridden() != 42) throw AssertionError()
+    if (Test().testOverridden(Z(123)) != 123) throw AssertionError()
+
+    return "OK"
+}

compiler/testData/codegen/box/inlineClasses/defaultParameterValuesOfInlineClassType.kt

@@ -0,0 +1,13 @@
+// !LANGUAGE: +InlineClasses
+// IGNORE_BACKEND: JVM_IR
+
+inline class Z(val z: Int)
+
+fun test(z: Z = Z(42)) = z.z
+
+fun box(): String {
+    if (test() != 42) throw AssertionError()
+    if (test(Z(123)) != 123) throw AssertionError()
+
+    return "OK"
+}

compiler/testData/codegen/box/inlineClasses/defaultParameterValuesOfInlineClassTypeBoxing.kt

@@ -0,0 +1,29 @@
+// !LANGUAGE: +InlineClasses
+// IGNORE_BACKEND: JVM_IR
+
+interface IFoo {
+    fun foo(): String
+}
+
+inline class Z(val z: Int) : IFoo {
+    override fun foo() = z.toString()
+}
+
+fun testNullable(z: Z? = Z(42)) = z!!.z
+
+fun testAny(z: Any = Z(42)) = (z as Z).z
+
+fun testInterface(z: IFoo = Z(42)) = z.foo()
+
+fun box(): String {
+    if (testNullable() != 42) throw AssertionError()
+    if (testNullable(Z(123)) != 123) throw AssertionError()
+
+    if (testAny() != 42) throw AssertionError()
+    if (testAny(Z(123)) != 123) throw AssertionError()
+
+    if (testInterface() != "42") throw AssertionError()
+    if (testInterface(Z(123)) != "123") throw AssertionError()
+
+    return "OK"
+}