Prevent 0 from being used to construct the identity.

sagemath · Nov 7, 2014 · c65cb5e · c65cb5e
1 parent 9121d13
commit c65cb5e
Showing 1 changed file with 9 additions and 1 deletion.
diff --git a/src/sage/groups/free_group.py b/src/sage/groups/free_group.py
@@ -811,11 +811,19 @@ def _element_constructor_(self, *args, **kwds):
             sage: F = FreeGroup(0)
             sage: F([])
             1
+
+        Check that 0 isn't considered the identity::
+
+            sage: F = FreeGroup('x')
+            sage: F(0)
+            Traceback (most recent call last):
+            ...
+            TypeError: 'sage.rings.integer.Integer' object is not iterable
         """
         if len(args)!=1:
             return self.element_class(self, *args, **kwds)
         x = args[0]
-        if x==1 or not x:
+        if x==1 or (not x and x != 0):
             return self.one()
         try:
             P = x.parent()