Merge pull request #12 from dls-controls/fix-python-3.7

Fix python 3.7

.travis.yml

@@ -1,13 +1,12 @@
 sudo: false
+dist: xenial
 language: python
 python:
   - "2.7"
-  - "3.3"
   - "3.4"
   - "3.5"
   - "3.6"
-
-
+  - "3.7"
 
 # Get epics base
 addons:

context/_coroutine.c

@@ -85,9 +85,15 @@ static void *coroutine_wrapper(void *action_, void *arg_)
 
     /* Also reset the exception state in case it's non NULL at this point.  We
      * don't own these pointers at this point, coroutine_switch does. */
+#if PY_VERSION_HEX >= 0x03070000
+    /* In Python 3.7 the exec info moved. */
+    thread_state->exc_state = (_PyErr_StackItem) { };
+    thread_state->exc_info = &thread_state->exc_state;
+#else
     thread_state->exc_type = NULL;
     thread_state->exc_value = NULL;
     thread_state->exc_traceback = NULL;
+#endif
 
     /* Call the given action with the passed argument. */
     PyObject *action = *(PyObject **)action_;
@@ -102,9 +108,15 @@ static void *coroutine_wrapper(void *action_, void *arg_)
      *    All these pointers really are defunct, because as soon as we return
      * coroutine_switch will replace all these values. */
     Py_XDECREF(thread_state->frame);
+#if PY_VERSION_HEX >= 0x03070000
+    Py_XDECREF(thread_state->exc_state.exc_type);
+    Py_XDECREF(thread_state->exc_state.exc_value);
+    Py_XDECREF(thread_state->exc_state.exc_traceback);
+#else
     Py_XDECREF(thread_state->exc_type);
     Py_XDECREF(thread_state->exc_value);
     Py_XDECREF(thread_state->exc_traceback);
+#endif
 
     return result;
 }
@@ -148,9 +160,14 @@ static PyObject *coroutine_switch(PyObject *Self, PyObject *args)
          * this then we get confusion about the lifetime of exception state
          * between coroutines.  The most obvious problem is that the exception
          * isn't properly cleared on function return. */
+#if PY_VERSION_HEX >= 0x03070000
+        _PyErr_StackItem exc_state = thread_state->exc_state;
+        _PyErr_StackItem *exc_info = thread_state->exc_info;
+#else
         PyObject *exc_type = thread_state->exc_type;
         PyObject *exc_value = thread_state->exc_value;
         PyObject *exc_traceback = thread_state->exc_traceback;
+#endif
 
         /* Switch to new coroutine.  For the duration arg needs an extra
          * reference count, it'll be accounted for either on the next returned
@@ -165,9 +182,14 @@ static PyObject *coroutine_switch(PyObject *Self, PyObject *args)
         thread_state->recursion_depth = recursion_depth;
 
         /* Restore the exception state. */
+#if PY_VERSION_HEX >= 0x03070000
+        thread_state->exc_state = exc_state;
+        thread_state->exc_info = exc_info;
+#else
         thread_state->exc_type = exc_type;
         thread_state->exc_value = exc_value;
         thread_state->exc_traceback = exc_traceback;
+#endif
         return result;
     }
     else