fix GetIteratorNode when the __iter__ method returns None (this fixes GR-10392)

- add new test to test_iter to check for cases when the iter is exhausted in a try/except block

Author: cosminbasca

graalpython/com.oracle.graal.python.test/src/tests/test_iterator.py

@@ -100,3 +100,16 @@ def test_iter():
 
 def test_zip_no_args():
     assert list(zip(*[])) == []
+
+
+def test_iter_try_except():
+    it = iter(range(3))
+    exit_via_break = False
+    while 1:
+        try:
+            next(it)
+        except StopIteration:
+            exit_via_break = True
+            break
+
+    assert exit_via_break

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/control/GetIteratorNode.java

@@ -25,6 +25,9 @@
  */
 package com.oracle.graal.python.nodes.control;
 
+import static com.oracle.graal.python.nodes.SpecialMethodNames.__GETITEM__;
+import static com.oracle.graal.python.nodes.SpecialMethodNames.__ITER__;
+import static com.oracle.graal.python.nodes.SpecialMethodNames.__NEXT__;
 import static com.oracle.graal.python.runtime.exception.PythonErrorType.TypeError;
 
 import com.oracle.graal.python.builtins.objects.PNone;
@@ -41,7 +44,6 @@
 import com.oracle.graal.python.builtins.objects.range.PRange;
 import com.oracle.graal.python.builtins.objects.type.PythonClass;
 import com.oracle.graal.python.nodes.PNode;
-import com.oracle.graal.python.nodes.SpecialMethodNames;
 import com.oracle.graal.python.nodes.argument.CreateArgumentsNode;
 import com.oracle.graal.python.nodes.attributes.LookupAttributeInMRONode;
 import com.oracle.graal.python.nodes.call.CallDispatchNode;
@@ -162,16 +164,16 @@ public Object doGeneric(Object value,
                     @Cached("create()") CreateArgumentsNode createArgs,
                     @Cached("create()") IsIteratorObjectNode isIteratorObjectNode) {
         PythonClass clazz = getClass(value);
-        Object attrObj = getattributeProfile.profile(lookupAttrMroNode.execute(clazz, SpecialMethodNames.__ITER__));
-        if (attrObj != PNone.NO_VALUE) {
-            Object iterObj = dispatchGetattribute.executeCall(attrObj, createArgs.execute(new Object[]{value}), PKeyword.EMPTY_KEYWORDS);
+        Object attrObj = getattributeProfile.profile(lookupAttrMroNode.execute(clazz, __ITER__));
+        if (attrObj != PNone.NO_VALUE && attrObj != PNone.NONE) {
+            Object iterObj = dispatchGetattribute.executeCall(attrObj, createArgs.execute(value), PKeyword.EMPTY_KEYWORDS);
             if (isIteratorObjectNode.execute(iterObj)) {
                 return iterObj;
             } else {
                 throw nonIterator(iterObj);
             }
         } else {
-            Object getItemAttrObj = lookupGetitemAttrMroNode.execute(clazz, SpecialMethodNames.__GETITEM__);
+            Object getItemAttrObj = lookupGetitemAttrMroNode.execute(clazz, __GETITEM__);
             if (getItemAttrObj != PNone.NO_VALUE) {
                 return factory().createSequenceIterator(value);
             }
@@ -206,7 +208,7 @@ boolean doPIterator(@SuppressWarnings("unused") PBuiltinIterator it) {
         boolean doPIterator(Object it,
                         @Cached("create()") GetClassNode getClassNode,
                         @Cached("create()") LookupAttributeInMRONode lookupAttributeNode) {
-            return lookupAttributeNode.execute(getClassNode.execute(it), SpecialMethodNames.__NEXT__) != PNone.NO_VALUE;
+            return lookupAttributeNode.execute(getClassNode.execute(it), __NEXT__) != PNone.NO_VALUE;
         }
 
         public static IsIteratorObjectNode create() {

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/datamodel/IsIterableNode.java

@@ -38,6 +38,7 @@
  */
 package com.oracle.graal.python.nodes.datamodel;
 
+import static com.oracle.graal.python.nodes.SpecialMethodNames.__GETITEM__;
 import static com.oracle.graal.python.nodes.SpecialMethodNames.__ITER__;
 import static com.oracle.graal.python.nodes.SpecialMethodNames.__NEXT__;
 
@@ -57,8 +58,11 @@
 public abstract class IsIterableNode extends PDataModelEmulationNode {
     @Child private HasInheritedAttributeNode hasNextNode = HasInheritedAttributeNode.create(__NEXT__);
     @Child private LookupInheritedAttributeNode getIterNode = LookupInheritedAttributeNode.create();
+    @Child private LookupInheritedAttributeNode getGetItemNode = LookupInheritedAttributeNode.create();
+    @Child private IsCallableNode isCallableNode = IsCallableNode.create();
 
     private final ConditionProfile profileIter = ConditionProfile.createBinaryProfile();
+    private final ConditionProfile profileGetItem = ConditionProfile.createBinaryProfile();
     private final ConditionProfile profileNext = ConditionProfile.createBinaryProfile();
 
     @Specialization
@@ -104,11 +108,17 @@ public boolean isIterable(@SuppressWarnings("unused") PZip zip) {
     @Specialization
     public boolean isIterable(Object object) {
         Object iterMethod = getIterNode.execute(object, __ITER__);
-        if (profileIter.profile(iterMethod != PNone.NO_VALUE)) {
-            return iterMethod != PNone.NONE;
+        if (profileIter.profile(iterMethod != PNone.NO_VALUE && iterMethod != PNone.NONE)) {
+            return true;
         } else {
-            return profileNext.profile(hasNextNode.execute(object));
+            Object getItemMethod = getGetItemNode.execute(object, __GETITEM__);
+            if (profileGetItem.profile(getItemMethod != PNone.NO_VALUE)) {
+                return true;
+            } else if (isCallableNode.execute(object)) {
+                return profileNext.profile(hasNextNode.execute(object));
+            }
         }
+        return false;
     }
 
     public static IsIterableNode create() {