Clean up our iternext handling

ie try to avoid api conversion.

src/capi/typeobject.cpp

@@ -827,7 +827,7 @@ static PyObject* slot_tp_iter(PyObject* self) noexcept {
     return PySeqIter_New(self);
 }
 
-static PyObject* slot_tp_iternext(PyObject* self) noexcept {
+/* Pyston change: static */ PyObject* slot_tp_iternext(PyObject* self) noexcept {
     STAT_TIMER(t0, "us_timer_slot_tpiternext", SLOT_AVOIDABILITY(self));
 
     static PyObject* next_str;

src/capi/typeobject.h

@@ -35,6 +35,7 @@ PyObject* mro_external(PyObject* self) noexcept;
 int type_set_bases(PyTypeObject* type, PyObject* value, void* context) noexcept;
 
 PyObject* slot_tp_richcompare(PyObject* self, PyObject* other, int op) noexcept;
+PyObject* slot_tp_iternext(PyObject* self) noexcept;
 }
 
 #endif

src/core/types.h

@@ -531,7 +531,6 @@ public:
     BoxedString* reprICAsString();
     bool nonzeroIC();
     Box* hasnextOrNullIC();
-    Box* nextIC();
 
     friend class AttrWrapper;
 };

src/runtime/capi.cpp

@@ -633,25 +633,6 @@ extern "C" int PyObject_Print(PyObject* obj, FILE* fp, int flags) noexcept {
     return internal_print(obj, fp, flags, 0);
 };
 
-extern "C" PyObject* PyIter_Next(PyObject* iter) noexcept {
-    try {
-        Box* hasnext = iter->hasnextOrNullIC();
-        if (hasnext) {
-            if (hasnext->nonzeroIC())
-                return iter->nextIC();
-            else
-                return NULL;
-        } else {
-            return iter->nextIC();
-        }
-    } catch (ExcInfo e) {
-        if (e.matches(StopIteration))
-            return NULL;
-        setCAPIException(e);
-    }
-    return NULL;
-}
-
 extern "C" int PyCallable_Check(PyObject* x) noexcept {
     if (x == NULL)
         return 0;

src/runtime/iterators.cpp

@@ -41,24 +41,11 @@ public:
     void next() override {
         STAT_TIMER(t0, "us_timer_iteratorgeneric_next", 0);
 
-        assert(iterator);
-        Box* hasnext = iterator->hasnextOrNullIC();
-        if (hasnext) {
-            if (hasnext->nonzeroIC()) {
-                value = iterator->nextIC();
-            } else {
-                *this = *end();
-            }
-        } else {
-            try {
-                value = iterator->nextIC();
-            } catch (ExcInfo e) {
-                if (e.matches(StopIteration))
-                    *this = *end();
-                else
-                    throw e;
-            }
-        }
+        Box* next = PyIter_Next(iterator);
+        if (next)
+            value = next;
+        else
+            *this = *end();
     }
 
     Box* getValue() override { return value; }

src/runtime/iterobject.cpp

@@ -132,20 +132,14 @@ bool iterwrapperHasnextUnboxed(Box* s) {
     RELEASE_ASSERT(s->cls == iterwrapper_cls, "");
     BoxedIterWrapper* self = static_cast<BoxedIterWrapper*>(s);
 
-    static BoxedString* next_str = static_cast<BoxedString*>(PyString_InternFromString("next"));
-    Box* next;
-    try {
-        next = callattr(self->iter, next_str, CallattrFlags({.cls_only = true, .null_on_nonexistent = false }),
-                        ArgPassSpec(0), NULL, NULL, NULL, NULL, NULL);
-    } catch (ExcInfo e) {
-        if (e.matches(StopIteration)) {
-            self->next = NULL;
-            return false;
-        }
-        throw e;
-    }
+    Box* next = PyIter_Next(self->iter);
     self->next = next;
-    return true;
+    if (!next) {
+        if (PyErr_Occurred() && !PyErr_ExceptionMatches(PyExc_StopIteration))
+            throwCAPIException();
+        PyErr_Clear();
+    }
+    return next != NULL;
 }
 
 Box* iterwrapperHasnext(Box* s) {

src/runtime/types.cpp

@@ -238,9 +238,38 @@ Box* BoxedClass::callHasnextIC(Box* obj, bool null_on_nonexistent) {
                     ArgPassSpec(0), nullptr, nullptr, nullptr, nullptr, nullptr);
 }
 
+extern "C" PyObject* PyIter_Next(PyObject* iter) noexcept {
+    if (iter->cls->tp_iternext != slot_tp_iternext) {
+        PyObject* result;
+        result = (*iter->cls->tp_iternext)(iter);
+        if (result == NULL && PyErr_Occurred() && PyErr_ExceptionMatches(PyExc_StopIteration))
+            PyErr_Clear();
+        return result;
+    }
+
+    try {
+        Box* hasnext = iter->hasnextOrNullIC();
+        if (hasnext) {
+            if (hasnext->nonzeroIC())
+                return iter->cls->callNextIC(iter);
+            else
+                return NULL;
+        } else {
+            return iter->cls->callNextIC(iter);
+        }
+    } catch (ExcInfo e) {
+        if (!e.matches(StopIteration))
+            setCAPIException(e);
+        return NULL;
+    }
+}
+
 Box* BoxedClass::callNextIC(Box* obj) {
     assert(obj->cls == this);
 
+    // This would work, but it would have been better to just call tp_iternext
+    assert(this->tp_iternext == slot_tp_iternext);
+
     auto ic = next_ic.get();
     if (!ic) {
         ic = new CallattrIC();
@@ -303,11 +332,6 @@ Box* Box::hasnextOrNullIC() {
     return this->cls->callHasnextIC(this, true);
 }
 
-Box* Box::nextIC() {
-    return this->cls->callNextIC(this);
-}
-
-
 std::string builtinStr("__builtin__");
 
 extern "C" BoxedFunctionBase::BoxedFunctionBase(CLFunction* f)