Revert dataflow changes, extract actual iterator function

Author: tamasvajk

java/kotlin-extractor/src/main/kotlin/KotlinFileExtractor.kt

@@ -1347,6 +1347,23 @@ open class KotlinFileExtractor(
         return result
     }
 
+    private fun findTopLevelFunctionOrWarn(functionFilter: String, type: String, warnAgainstElement: IrElement): IrFunction? {
+
+        val fn = pluginContext.referenceFunctions(FqName(functionFilter))
+            .firstOrNull { it.owner.parentClassOrNull?.fqNameWhenAvailable?.asString() == type }
+            ?.owner
+
+        if (fn != null) {
+            if (fn.parentClassOrNull != null) {
+                extractExternalClassLater(fn.parentAsClass)
+            }
+        } else {
+            logger.errorElement("Couldn't find JVM intrinsic function $functionFilter in $type", warnAgainstElement)
+        }
+
+        return fn
+    }
+
     val javaLangString by lazy {
         val result = pluginContext.referenceClass(FqName("java.lang.String"))?.owner
         result?.let { extractExternalClassLater(it) }
@@ -1860,6 +1877,11 @@ open class KotlinFileExtractor(
                         }
                     }
                 }
+                isFunction(target, "kotlin", "(some array type)", { isArrayType(it) }, "iterator") && c.origin == IrStatementOrigin.FOR_LOOP_ITERATOR -> {
+                    findTopLevelFunctionOrWarn("kotlin.jvm.internal.iterator", "kotlin.jvm.internal.ArrayIteratorKt", c)?.let { iteratorFn ->
+                        extractRawMethodAccess(iteratorFn, c, callable, parent, idx, enclosingStmt, listOf(c.dispatchReceiver), null, null, listOf((c.dispatchReceiver!!.type as IrSimpleType).arguments.first().typeOrNull!!))
+                    }
+                }
                 isFunction(target, "kotlin", "(some array type)", { isArrayType(it) }, "get") && c.origin == IrStatementOrigin.GET_ARRAY_ELEMENT -> {
                     val id = tw.getFreshIdLabel<DbArrayaccess>()
                     val type = useType(c.type)

java/ql/lib/semmle/code/java/dataflow/internal/DataFlowPrivate.qll

@@ -205,11 +205,6 @@ private predicate canContainBool(Type t) {
   any(BooleanType b).(RefType).getASourceSupertype+() = t
 }
 
-private predicate isArray(Type t) {
-  t instanceof Array or
-  t.(RefType).getSourceDeclaration().hasQualifiedName("kotlin", "Array")
-}
-
 /**
  * Holds if `t1` and `t2` are compatible, that is, whether data can flow from
  * a node of type `t1` to a node of type `t2`.
@@ -226,9 +221,6 @@ predicate compatibleTypes(Type t1, Type t2) {
     erasedHaveIntersection(e1, e2)
     or
     canContainBool(e1) and canContainBool(e2)
-    or
-    // Make java array and `kotlin.Array` types compatible.
-    isArray(e1) and isArray(e2)
   )
 }
 

java/ql/lib/semmle/code/java/frameworks/KotlinStdLib.qll

@@ -5,6 +5,9 @@ private import semmle.code.java.dataflow.ExternalFlow
 
 private class KotlinStdLibSummaryCsv extends SummaryModelCsv {
   override predicate row(string row) {
-    row = ["kotlin;Array;false;iterator;();;Argument[-1].ArrayElement;ReturnValue.Element;value"]
+    row =
+      [
+        "kotlin.jvm.internal;ArrayIteratorKt;false;iterator;(Object[]);;Argument[0].ArrayElement;ReturnValue.Element;value"
+      ]
   }
 }