From f81cbe9fec1a1edb526d48a8fbe41aa88b2de85d Mon Sep 17 00:00:00 2001
From: Hans Dembinski <hans.dembinski@gmail.com>
Date: Fri, 24 Mar 2017 21:33:01 +0100
Subject: [PATCH] fix bug for conversion of uninitialized histogram

---
 src/python/histogram.cpp     | 10 ++++------
 test/python_suite_test.py.in | 11 +++++++++++
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/src/python/histogram.cpp b/src/python/histogram.cpp
index 34c66824..19226a64 100644
--- a/src/python/histogram.cpp
+++ b/src/python/histogram.cpp
@@ -272,7 +272,7 @@ struct storage_access {
   static
   python::object
   array_interface(dynamic_histogram<>& self) {
-    const auto& b = self.storage_.buffer_;
+    auto& b = self.storage_.buffer_;
     if (b.type_.id_ == 5) {
       // PyErr_SetString(PyExc_KeyError, "cannot convert multiprecision storage to numpy array");
       // python::throw_error_already_set();
@@ -280,11 +280,9 @@ struct storage_access {
       return python::object();
     }
 
-    if (!b.ptr_) {
-      // PyErr_SetString(PyExc_KeyError, "cannot convert empty histogram");
-      // python::throw_error_already_set();
-      // workaround: for some reason, exception is ignored here
-      return python::object();
+    if (b.type_.id_ == 0) {
+      // buffer not created yet, do that now
+      b.template initialize<uint8_t>();
     }
 
     python::dict d;
diff --git a/test/python_suite_test.py.in b/test/python_suite_test.py.in
index 80cd37bd..396a96b8 100755
--- a/test/python_suite_test.py.in
+++ b/test/python_suite_test.py.in
@@ -645,6 +645,17 @@ class histogramtest(unittest.TestCase):
         self.assertTrue(numpy.all(c == r))
         self.assertTrue(numpy.all(v == r))
 
+    @unittest.skipUnless(have_numpy, "requires build with numpy-support")
+    def test_numpy_conversion_4(self):
+        a = histogram(integer_axis(0, 1, uoflow=False))
+        a1 = numpy.asarray(a)
+        self.assertEqual(a1.dtype, numpy.uint8)
+        self.assertEqual(a1.shape, (2,))
+
+        b = histogram()
+        b1 = numpy.asarray(b)
+        self.assertEqual(b1, 0)
+
     @unittest.skipUnless(have_numpy, "requires build with numpy-support")
     def test_bad_numpy_conversion(self):
         a = histogram(integer_axis(0, 0))