Made todo for unaddressed global iterator name bug

docs/todo.rst

@@ -5,5 +5,6 @@ TODO List
 .. todo:: Implement decorator to eliminate unused lines of code (assignments to unused values)
 .. todo:: Technically, ``x += y`` doesn't have to be the same thing as ``x = x + y``. Handle it as its own operation of the form ``x += y; return x``
 .. todo:: Support efficiently inlining simple functions, i.e. where there is no return or only one return as the last line of the function, using pure name substitution without loops, try/except, or anything else fancy
+.. todo:: Catch replacement of loop variables that conflict with globals, or throw a more descriptive error when detected. See ``test_iteration_variable``
 
 .. todolist::

tests/test_collapse_literals.py

@@ -151,6 +151,33 @@ def f2():
             for a in range(3): # failure occurs when this is interpreted as "for 0 in range(3)"
                 x = a
 
+    def test_iteration_variable(self):
+        # global glbvar  # TODO: Uncommenting should lead to a descriptive error
+        glbvar = 0
+
+        # glbvar in <locals> is recognized as in the __closure__ of f1
+        @pragma.collapse_literals
+        def f1():
+            x = glbvar
+        result = '''
+        def f1():
+            x = 0
+        '''
+        self.assertSourceEqual(f1, result)
+
+        # glbvar in <locals> is recognized as NOT in the __closure__ of f2
+        # but, if glbvar is in __globals__, it fails (and maybe should)
+        @pragma.collapse_literals
+        def f2():
+            for glbvar in range(3):
+                x = glbvar
+        result = '''
+        def f2():
+            for glbvar in range(3):
+                x = glbvar
+        '''
+        self.assertSourceEqual(f2, result)
+
     def test_conditional_erasure(self):
         @pragma.collapse_literals
         def f(y):