Introduce FirForLoopChecker

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

@@ -1,22 +0,0 @@
-// !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<!UNSAFE_CALL!>.<!>iterator()
-    // for extension iterator, this code compiles, but should not
-    <!UNSAFE_CALL!>for (s in container) {}<!>
-}
-class OtherContainer<K>(val k: K) {
-    operator fun iterator(): Iterator<K> = null!!
-}
-
-fun test2() {
-    val other: OtherContainer<String>? = null
-    // Error
-    <!UNSAFE_CALL!>for (s in other) {}<!>
-}

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

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // !WITH_NEW_INFERENCE
 // See also KT-7428
 class Container<K>(val k: K)

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

@@ -1,7 +1,7 @@
 
 fun foo1() = <!EXPRESSION_EXPECTED!>while (b()) {}<!>
 
-fun foo2() = <!UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for (i in 10) {}<!>
+fun foo2() = for (i in <!ITERATOR_MISSING!>10<!>) {}
 
 fun foo3() = when (b()) {
     true -> 1

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

@@ -8,7 +8,7 @@ class It {
 }
 
 fun test(c: Coll?) {
-  <!UNSAFE_CALL!>for (x in c) {}<!>
+  for (x in <!ITERATOR_ON_NULLABLE!>c<!>) {}
 
   if (c != null) {
     for(x in c) {}

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

@@ -8,5 +8,5 @@ class It {
 }
 
 fun test() {
-  <!UNSAFE_CALL, UNSAFE_CALL!>for (x in Coll()) {}<!>
+  for (x in <!HAS_NEXT_FUNCTION_NONE_APPLICABLE!>Coll()<!>) {}
 }