Report error if fun interface method has JVM name getFunctionDelegate

This is needed so that it wouldn't clash with the corresponding member
from the kotlin/jvm/internal/FunctionAdapter interface, which all fun
interface wrappers will implement to get proper equals/hashCode. The
workaround is to rename the fun interface method.

 #KT-33455

compiler/testData/diagnostics/tests/funInterface/functionDelegateClashOnJvm.fir.kt

@@ -0,0 +1,32 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun interface F1 {
+    val functionDelegate: Function<*>? get() = null
+    fun invoke()
+}
+
+fun interface F2 {
+    fun getFunctionDelegate(): Function<*>? = null
+    fun invoke()
+}
+
+fun interface F3 {
+    val getFunctionDelegate: Function<*>? get() = null
+    fun invoke()
+}
+
+fun interface F4 {
+    fun functionDelegate(): Function<*>? = null
+    fun invoke()
+}
+
+fun interface F5 {
+    val functionDelegate: Any? get() = null
+    fun invoke()
+}
+
+fun interface F6 {
+    val String.functionDelegate: Function<*>? get() = null
+    fun getFunctionDelegate(x: Any?): Function<*>? = null
+    fun invoke()
+}

compiler/testData/diagnostics/tests/funInterface/functionDelegateClashOnJvm.kt

@@ -0,0 +1,32 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun interface F1 {
+    val <!FUNCTION_DELEGATE_MEMBER_NAME_CLASH!>functionDelegate<!>: Function<*>? get() = null
+    fun invoke()
+}
+
+fun interface F2 {
+    fun <!FUNCTION_DELEGATE_MEMBER_NAME_CLASH!>getFunctionDelegate<!>(): Function<*>? = null
+    fun invoke()
+}
+
+fun interface F3 {
+    val getFunctionDelegate: Function<*>? get() = null
+    fun invoke()
+}
+
+fun interface F4 {
+    fun functionDelegate(): Function<*>? = null
+    fun invoke()
+}
+
+fun interface F5 {
+    val <!FUNCTION_DELEGATE_MEMBER_NAME_CLASH!>functionDelegate<!>: Any? get() = null
+    fun invoke()
+}
+
+fun interface F6 {
+    val String.functionDelegate: Function<*>? get() = null
+    fun getFunctionDelegate(x: Any?): Function<*>? = null
+    fun invoke()
+}

compiler/testData/diagnostics/tests/funInterface/functionDelegateClashOnJvm.txt

@@ -0,0 +1,50 @@
+package
+
+public fun interface F1 {
+    public open val functionDelegate: kotlin.Function<*>?
+    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 abstract fun invoke(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public fun interface F2 {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open fun getFunctionDelegate(): kotlin.Function<*>?
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public abstract fun invoke(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public fun interface F3 {
+    public open val getFunctionDelegate: kotlin.Function<*>?
+    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 abstract fun invoke(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public fun interface F4 {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open fun functionDelegate(): kotlin.Function<*>?
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public abstract fun invoke(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public fun interface F5 {
+    public open val functionDelegate: kotlin.Any?
+    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 abstract fun invoke(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public fun interface F6 {
+    public open val kotlin.String.functionDelegate: kotlin.Function<*>?
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open fun getFunctionDelegate(/*0*/ x: kotlin.Any?): kotlin.Function<*>?
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public abstract fun invoke(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}