bad_var now fails on single None

theano/gof/tests/test_utils.py

 import theano
 from theano.gof.utils import give_variables_names, unique
 
-def test_variables_with_names():
+def test_give_variables_names():
     x = theano.tensor.matrix('x')
     y = x + 1
     z = theano.tensor.dot(x, y)
@@ -9,3 +9,12 @@ def test_variables_with_names():
     give_variables_names(variables)
     assert all(var.name for var in variables)
     assert unique([var.name for var in variables])
+
+def test_give_variables_names_small():
+    x = theano.tensor.matrix('x')
+    y = theano.tensor.dot(x, x)
+    fgraph = theano.FunctionGraph((x,), (y,))
+    give_variables_names(fgraph.variables)
+    assert all(var.name for var in fgraph.variables)
+    assert unique([var.name for var in fgraph.variables])
+

theano/gof/utils.py

@@ -344,7 +344,7 @@ def give_variables_names(variables):
     """ Gives unique names to an iterable of variables. Modifies input."""
     names = map(lambda var: var.name, variables)
     h = hist(names)
-    bad_var = lambda var: h[var.name] > 1
+    bad_var = lambda var: not var.name or h[var.name] > 1
 
     for i, var in enumerate(filter(bad_var, variables)):
         var.name = (var.name or "") + "_%d"%i