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Assertion error when running tests on Python 3.6 compiled in debug mode

Hi,

I'm trying to run the numpy test suite on the development version of Python 3.6 with Python compiled in debug mode, but I had two issues:

  • Cython doesn't work on Python 3.6 anymore: http://bugs.python.org/issue26519
  • _convert_from_dict() function of numpy/core/src/multiarray/descriptor.c calls directly or indirectly PyObject_GetItem() with an exception set, it's no more allowed in debug mode, since PyObject_GetItem() may clear the current exception.

Following patch (incomplete, see the FIXME) works around assertion errors raised by the test suite:

diff --git a/numpy/core/src/multiarray/descriptor.c b/numpy/core/src/multiarray/descriptor.c
index 03a4654..f9fd714 100644
--- a/numpy/core/src/multiarray/descriptor.c
+++ b/numpy/core/src/multiarray/descriptor.c
@@ -977,7 +977,10 @@ _convert_from_dict(PyObject *obj, int align)
      * Use PyMapping_GetItemString to support dictproxy objects as well.
      */
     names = Borrowed_PyMapping_GetItemString(obj, "names");
-    descrs = Borrowed_PyMapping_GetItemString(obj, "formats");
+    if (names)
+        descrs = Borrowed_PyMapping_GetItemString(obj, "formats");
+    else
+        descrs = NULL;
     if (!names || !descrs) {
         Py_DECREF(fields);
         PyErr_Clear();
@@ -985,8 +988,11 @@ _convert_from_dict(PyObject *obj, int align)
     }
     n = PyObject_Length(names);
     offsets = Borrowed_PyMapping_GetItemString(obj, "offsets");
+    if (!offsets) {
+        PyErr_Clear();
+    }
     titles = Borrowed_PyMapping_GetItemString(obj, "titles");
-    if (!offsets || !titles) {
+    if (!titles) {
         PyErr_Clear();
     }

@@ -1080,6 +1086,8 @@ _convert_from_dict(PyObject *obj, int align)
                         "with align=True",
                         (int)offset, (int)newdescr->alignment);
                 ret = NPY_FAIL;
+                /* FIXME: fix ref leaks! ind, tup, ... */
+                goto fail;
             }
             else if (offset + newdescr->elsize > totalsize) {
                 totalsize = offset + newdescr->elsize;

IMHO this function must be rewritten to handle exceptions differently: give up earlier. See also the issue #7360 which is a similar issue, but in a different C function of numpy (ufunc_generic_call).