optimize: tuple(ob) -> PySequence_Tuple(ob)

Cython/Compiler/Optimize.py

@@ -2026,24 +2026,29 @@ class OptimizeBuiltinCalls(Visitor.NodeRefCleanupMixin,
             PyrexTypes.CFuncTypeArg("list", Builtin.list_type, None)
             ])
 
+    PySequence_Tuple_func_type = PyrexTypes.CFuncType(
+        Builtin.tuple_type,
+        [PyrexTypes.CFuncTypeArg("it", PyrexTypes.py_object_type, None)])
+
     def _handle_simple_function_tuple(self, node, function, pos_args):
-        """Replace tuple([...]) by a call to PyList_AsTuple.
+        """Replace tuple([...]) by PyList_AsTuple or PySequence_Tuple.
         """
         if len(pos_args) != 1:
             return node
         arg = pos_args[0]
         if arg.type is Builtin.tuple_type and not arg.may_be_none():
             return arg
-        if arg.type is not Builtin.list_type:
-            return node
+        if arg.type is Builtin.list_type:
             pos_args[0] = arg.as_none_safe_node(
                 "'NoneType' object is not iterable")
 
             return ExprNodes.PythonCapiCallNode(
                 node.pos, "PyList_AsTuple", self.PyList_AsTuple_func_type,
-            args = pos_args,
-            is_temp = node.is_temp
-            )
+                args=pos_args, is_temp=node.is_temp)
+        else:
+            return ExprNodes.PythonCapiCallNode(
+                node.pos, "PySequence_Tuple", self.PySequence_Tuple_func_type,
+                args=pos_args, is_temp=node.is_temp)
 
     PySet_New_func_type = PyrexTypes.CFuncType(
         Builtin.set_type, [

tests/run/tuple.pyx

@@ -114,9 +114,21 @@ def tuple_of_args_tuple(*args):
     return tuple(tuple(tuple(args)))
 
 
+@cython.test_fail_if_path_exists('//SimpleCallNode//SimpleCallNode')
+def tuple_of_object(ob):
+    """
+    >>> tuple(type(1))
+    Traceback (most recent call last):
+    TypeError: 'type' object is not iterable
+    >>> sorted(tuple(set([1, 2, 3])))
+    [1, 2, 3]
+    """
+    return tuple(ob)
+
+
 @cython.test_fail_if_path_exists(
-    '//SimpleCallNode//SimpleCallNode',
-    '//PythonCapiCallNode'
+    '//SimpleCallNode',
+    '//PythonCapiCallNode//PythonCapiCallNode'
 )
 def tuple_of_tuple_or_none(tuple x):
     """