# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1486243583 -3600
# Node ID b7334adb7dec68d7ffc81d5960cc67898b976929
# Parent  0495cc21f241dd3bb0e446240a51a7cd83addd06
Handle situations where a global accidentally refers to a built-in module.

diff -r 0495cc21f241 -r b7334adb7dec importer.py
--- a/importer.py	Sat Feb 04 18:10:20 2017 +0100
+++ b/importer.py	Sat Feb 04 22:26:23 2017 +0100
@@ -444,6 +444,13 @@
 
                     if provider and provider != module.name:
 
+                        # Handle built-in modules accidentally referenced by
+                        # names.
+
+                        if provider == "__builtins__" and found.has_kind("<module>"):
+                            raise ProgramError("Name %s, used by %s, refers to module %s." %
+                                               (found.leaf(), module.name, found.get_origin()))
+
                         # Record the provider dependency.
 
                         module.required.add(provider)
diff -r 0495cc21f241 -r b7334adb7dec referencing.py
--- a/referencing.py	Sat Feb 04 18:10:20 2017 +0100
+++ b/referencing.py	Sat Feb 04 22:26:23 2017 +0100
@@ -3,7 +3,7 @@
 """
 Reference abstractions.
 
-Copyright (C) 2016 Paul Boddie <paul@boddie.org.uk>
+Copyright (C) 2016, 2017 Paul Boddie <paul@boddie.org.uk>
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -187,6 +187,15 @@
 
         return self.get_name().rsplit(".", 1)[0]
 
+    def leaf(self):
+
+        "Return the leafname of the reference's origin."
+
+        if not self.get_origin():
+            return None
+
+        return self.get_origin().rsplit(".", 1)[-1]
+
     def ancestors(self):
 
         """