Forbidden old invokeExtension convention.

compiler/testData/diagnostics/tests/resolve/invoke/wrongInvokeExtension.kt

@@ -0,0 +1,20 @@
+class B
+
+class A {
+    operator fun B.invoke() {}
+}
+
+val B.a: () -> Int  get() = { 5 }
+
+fun test(a: A, b: B) {
+    val <!UNUSED_VARIABLE!>x<!>: Int = b.a()
+
+    b.<!INVOKE_EXTENSION_ON_NOT_EXTENSION_FUNCTION!>(a)<!>()
+
+    with(b) {
+        val <!UNUSED_VARIABLE!>y<!>: Int = a()
+        <!MISSING_RECEIVER!>(a)<!>()
+    }
+}
+
+fun <T, R> with(receiver: T, f: T.() -> R): R = receiver.f()