BUG: iter: Fix 0-size edge case with trivial iteration macros

4 files changed, 25 insertions, 4 deletions

diff --git a/numpy/core/src/multiarray/dtype_transfer.c b/numpy/core/src/multiarray/dtype_transfer.c
index 084683f96..8fdcd8a5d 100644
--- a/numpy/core/src/multiarray/dtype_transfer.c
+++ b/numpy/core/src/multiarray/dtype_transfer.c
@@ -17,8 +17,8 @@
 
 #define NPY_LOWLEVEL_BUFFER_BLOCKSIZE  128
 
-#define DTYPE_TRANSFER_REFTRACE(x, y)
-/*#define DTYPE_TRANSFER_REFTRACE printf*/
+#define DTYPE_TRANSFER_REFTRACE(...)
+/*#define DTYPE_TRANSFER_REFTRACE(...) printf(__VA_ARGS__)*/
 
 /*
  * Returns a transfer function which DECREFs any references in src_type.
diff --git a/numpy/core/src/multiarray/lowlevel_strided_loops.h b/numpy/core/src/multiarray/lowlevel_strided_loops.h
index 6e17e3fd7..1a6482398 100644
--- a/numpy/core/src/multiarray/lowlevel_strided_loops.h
+++ b/numpy/core/src/multiarray/lowlevel_strided_loops.h
@@ -330,6 +330,7 @@ PyArray_TransferStridedToNDim(npy_intp ndim,
                     npy_intp size1 = PyArray_SIZE(arr1); \
                     npy_intp size2 = PyArray_SIZE(arr2); \
                     count = size1 > size2 ? size1 : size2; \
+                    if (size1 == 0 || size2 == 0) count = 0; \
                     data1 = PyArray_BYTES(arr1); \
                     data2 = PyArray_BYTES(arr2); \
                     stride1 = (size1 == 1 ? 0 : \
@@ -374,6 +375,7 @@ PyArray_TransferStridedToNDim(npy_intp ndim,
                     npy_intp size3 = PyArray_SIZE(arr3); \
                     count = size1 > size2 ? size1 : size2; \
                     if (size3 > count) count = size3; \
+                    if (size1 == 0 || size2 == 0 || size2 == 0) count = 0; \
                     data1 = PyArray_BYTES(arr1); \
                     data2 = PyArray_BYTES(arr2); \
                     data3 = PyArray_BYTES(arr3); \
diff --git a/numpy/core/src/umath/ufunc_object.c b/numpy/core/src/umath/ufunc_object.c
index 2e52f568f..d1ef4dae4 100644
--- a/numpy/core/src/umath/ufunc_object.c
+++ b/numpy/core/src/umath/ufunc_object.c
@@ -43,8 +43,15 @@
 
 #define USE_USE_DEFAULTS 1
 
-/*#define NPY_UFUNC_DBG_PRINTF(...) printf(__VA_ARGS__)*/
+/********************/
+#if 0
+#define NPY_UFUNC_DBG_PRINTF(...) printf(__VA_ARGS__)
+#else
 #define NPY_UFUNC_DBG_PRINTF(...)
+#endif
+
+#define USE_NEW_ITERATOR_GENFUNC 1
+/********************/
 
 /* ---------------------------------------------------------------- */
 
@@ -5336,9 +5343,12 @@ static struct PyMethodDef ufunc_methods[] = {
     {"outer",
         (PyCFunction)ufunc_outer,
         METH_VARARGS | METH_KEYWORDS, NULL},
-    {"f", /* old generic call */
+    {"of", /* old generic call */
         (PyCFunction)ufunc_generic_call,
         METH_VARARGS | METH_KEYWORDS, NULL},
+    {"nf", /* new generic call */
+        (PyCFunction)ufunc_generic_call_iter,
+        METH_VARARGS | METH_KEYWORDS, NULL},
     {NULL, NULL, 0, NULL}           /* sentinel */
 };
 
@@ -5564,7 +5574,11 @@ NPY_NO_EXPORT PyTypeObject PyUFunc_Type = {
     0,                                          /* tp_as_sequence */
     0,                                          /* tp_as_mapping */
     0,                                          /* tp_hash */
+#if USE_NEW_ITERATOR_GENFUNC 
     (ternaryfunc)ufunc_generic_call_iter,       /* tp_call */
+#else
+    (ternaryfunc)ufunc_generic_call,            /* tp_call */
+#endif
     (reprfunc)ufunc_repr,                       /* tp_str */
     0,                                          /* tp_getattro */
     0,                                          /* tp_setattro */
diff --git a/numpy/core/tests/test_regression.py b/numpy/core/tests/test_regression.py
index 06055b2cd..04fd9210e 100644
--- a/numpy/core/tests/test_regression.py
+++ b/numpy/core/tests/test_regression.py
@@ -1441,5 +1441,10 @@ class TestRegression(TestCase):
         a = a.byteswap().newbyteorder()
         assert_equal(a.nonzero()[0], [1]) # [0] if nonzero() ignores swap
 
+    def test_empty_mul(self):
+        a = np.array([1.])
+        a[1:1] *= 2
+        assert_equal(a, [1.])
+
 if __name__ == "__main__":
     run_module_suite()