Fix optional argument resolution in cwrap

tools/cwrap/functions.py

@@ -63,24 +63,24 @@ static PyObject * THPTensor_(${name})(THPTensor *self, PyObject *args)
         calls add some overhead).
         """
         impl = ''
-        prev_arg_count = -1
+        prev_option = None
         for option in sorted(self.options, key=lambda o: o.num_required_args()):
             num_args = option.num_required_args()
-            if num_args > prev_arg_count:
+            prev_num_args = prev_option.num_required_args() if prev_option else -1
+            if num_args > prev_num_args:
                 # Nothing to close if it's the first option
-                if prev_arg_count != -1 and prev_arg_count < math.inf:
+                if prev_num_args != -1 and prev_option.check_argcount():
                     impl += '  }\n'
-                if num_args < math.inf:
+                if option.check_argcount():
                     impl += Template('  if (_argcount == $numargs) {') \
                                 .substitute({'numargs': num_args})
-                prev_arg_count = num_args
-            else:
-                impl += '    PyErr_Clear();'
             impl += '\n    {'
             impl += option.generate()
             impl += '    }\n'
+            impl += '    PyErr_Clear();'
+            prev_option = option
         # Close last argcount block
-        if prev_arg_count < math.inf:
+        if prev_option.check_argcount():
             impl += '  }\n'
         return impl
 
@@ -107,6 +107,7 @@ static PyObject * THPTensor_(${name})(THPTensor *self, PyObject *args)
         for option, optional_args in zip(self.options, self.optional_args):
             if not optional_args:
                 resolved_options.append(option)
+                continue
             # Generate options with all possible configurations of optional args
             for enabled_bits in product((True, False), repeat=len(optional_args)):
                 new_option = option.copy()

tools/cwrap/options.py

@@ -128,6 +128,9 @@ class Option(object):
         """
         return argcount(self)
 
+    def check_argcount(self):
+        return True
+
     def _library_state_macro(self, argstr):
         return 'LIBRARY_STATE' if argstr else 'LIBRARY_STATE_NOARGS'
 
@@ -206,5 +209,11 @@ class LongArgsTHOption(THOption):
             arg_idx += 1
         return init
 
+    def check_argcount(self):
+        return False
+
     def num_required_args(self):
-        return math.inf
+        # TODO: this is an ugly hack
+        # LONG_ARG options have to be sorted decreasingly w.r.t. number of arguments
+        # (ones with larger counts are more specific)
+        return 100000 - argcount(self)

torch/csrc/utils.cpp

@@ -34,11 +34,12 @@ int THPUtils_getCallable(PyObject *arg, PyObject **result) {
 }
 
 THLongStorage * THPUtils_getLongStorage(PyObject *args, int ignore_first) {
+// TODO: error messages
   long value;
 
   Py_ssize_t length = PyTuple_Size(args);
   if (length < ignore_first+1)
-      return NULL;
+    throw std::logic_error("Provided too few arguments");
 
   // Maybe there's a LongStorage
   PyObject *first_arg = PyTuple_GET_ITEM(args, ignore_first);
@@ -53,7 +54,7 @@ THLongStorage * THPUtils_getLongStorage(PyObject *args, int ignore_first) {
   for (Py_ssize_t i = ignore_first; i < length; ++i) {
     PyObject *arg = PyTuple_GET_ITEM(args, i);
     if (!THPUtils_getLong(arg, &value))
-        return NULL;
+        throw std::invalid_argument("Expected a numeric argument");
     result->data[i-ignore_first] = value;
   }
   return result.release();