[FIR-TEST] Add new testdata generated after changes in previous commit

compiler/testData/diagnostics/tests/controlStructures/ForLoopWithExtensionIteratorOnNullable.fir.kt

@@ -0,0 +1,22 @@
+// !WITH_NEW_INFERENCE
+// See also KT-7428
+class Container<K>(val k: K)
+// iterator() must be an extension, otherwise code will not compile
+operator fun <K> Container<K>.iterator(): Iterator<K> = null!!
+
+fun test() {
+    val container: Container<String>? = null
+    // Error
+    container.<!INAPPLICABLE_CANDIDATE!>iterator<!>()
+    // for extension iterator, this code compiles, but should not
+    <!INAPPLICABLE_CANDIDATE, UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for (s in container) {}<!>
+}
+class OtherContainer<K>(val k: K) {
+    operator fun iterator(): Iterator<K> = null!!
+}
+
+fun test2() {
+    val other: OtherContainer<String>? = null
+    // Error
+    <!INAPPLICABLE_CANDIDATE, UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for (s in other) {}<!>
+}