Replace assert with a proper error

diff --git a/Tools/clinic/clinic.py b/Tools/clinic/clinic.py
index 3d4feafd7f31862c23a9c34fb48503c478737b89..56e491168e8e3e4f380dc6dc2601c6a5dbb99a35 100755 (executable)
--- a/Tools/clinic/clinic.py
+++ b/Tools/clinic/clinic.py
@@ -2343,9 +2343,11 @@ class DSLParser:
                 fail("Badly-formed annotation for " + full_name + ": " + returns)
             try:
                 name, legacy, kwargs = self.parse_converter(module.body[0].returns)
-                assert not legacy
+                if legacy:
+                    fail("Legacy converter {!r} not allowed as a return converter"
+                         .format(name))
                 if name not in return_converters:
-                    fail("Error: No available return converter called " + repr(name))
+                    fail("No available return converter called " + repr(name))
                 return_converter = return_converters[name](**kwargs)
             except ValueError:
                 fail("Badly-formed annotation for " + full_name + ": " + returns)