Fix reference leak in the Py2.x __Pyx_ReleaseBuffer() implementation for types...

Fix reference leak in the Py2.x __Pyx_ReleaseBuffer() implementation for types with an overridden __releasebuffer__ method.

Closes #1638.

CHANGES.rst

@@ -14,6 +14,11 @@ Bugs fixed
 
 * ``cython.view.array`` was missing ``.__len__()``.
 
+* Extension types with a ``.pxd`` override for their ``__releasebuffer__`` slot
+  (e.g. as provided by Cython for the Python ``array.array`` type) could leak
+  a reference to the buffer owner on release, thus not freeing the memory.
+  (Github issue #1638)
+
 * Invalid C code in generators (declaration after code).
   (Github issue #1801)
 

Cython/Utility/Buffer.c

@@ -128,14 +128,15 @@ static void __Pyx_ReleaseBuffer(Py_buffer *view) {
         return;
     }
 
+    if ((0));
     {{for type_ptr, getbuffer, releasebuffer in types}}
       {{if releasebuffer}}
-        if (PyObject_TypeCheck(obj, {{type_ptr}})) { {{releasebuffer}}(obj, view); return; }
+        else if (PyObject_TypeCheck(obj, {{type_ptr}})) {{releasebuffer}}(obj, view);
       {{endif}}
     {{endfor}}
 
-    Py_DECREF(obj);
     view->obj = NULL;
+    Py_DECREF(obj);
 }
 
 #endif /*  PY_MAJOR_VERSION < 3 */