2 files changed, 59 insertions, 8 deletions

diff --git a/Lib/lib2to3/fixes/fix_next.py b/Lib/lib2to3/fixes/fix_next.py
index 9791333..9f1861e 100644
--- a/Lib/lib2to3/fixes/fix_next.py
+++ b/Lib/lib2to3/fixes/fix_next.py
@@ -28,15 +28,19 @@ class FixNext(fixer_base.BaseFix):
                      any* > >
     |
     global=global_stmt< 'global' any* 'next' any* >
-    |
-    mod=file_input< any+ >
     """
 
     order = "pre" # Pre-order tree traversal
 
     def start_tree(self, tree, filename):
         super(FixNext, self).start_tree(tree, filename)
-        self.shadowed_next = False
+
+        n = find_binding('next', tree)
+        if n:
+            self.warning(n, bind_warning)
+            self.shadowed_next = True
+        else:
+            self.shadowed_next = False
 
     def transform(self, node, results):
         assert results
@@ -69,11 +73,6 @@ class FixNext(fixer_base.BaseFix):
         elif "global" in results:
             self.warning(node, bind_warning)
             self.shadowed_next = True
-        elif mod:
-            n = find_binding('next', mod)
-            if n:
-                self.warning(n, bind_warning)
-                self.shadowed_next = True
 
 
 ### The following functions help test if node is part of an assignment
diff --git a/Lib/lib2to3/fixes/fix_set_literal.py b/Lib/lib2to3/fixes/fix_set_literal.py
new file mode 100644
index 0000000..414b1df
--- /dev/null
+++ b/Lib/lib2to3/fixes/fix_set_literal.py
@@ -0,0 +1,52 @@
+"""
+Optional fixer to transform set() calls to set literals.
+"""
+
+# Author: Benjamin Peterson
+
+from lib2to3 import fixer_base, pytree
+from lib2to3.fixer_util import token, syms
+
+
+
+class FixSetLiteral(fixer_base.BaseFix):
+
+    explicit = True
+
+    PATTERN = """power< 'set' trailer< '('
+                     (atom=atom< '[' (items=listmaker< any ((',' any)* [',']) >
+                                |
+                                single=any) ']' >
+                     |
+                     atom< '(' items=testlist_gexp< any ((',' any)* [',']) > ')' >
+                     )
+                     ')' > >
+              """
+
+    def transform(self, node, results):
+        single = results.get("single")
+        if single:
+            # Make a fake listmaker
+            fake = pytree.Node(syms.listmaker, [single.clone()])
+            single.replace(fake)
+            items = fake
+        else:
+            items = results["items"]
+
+        # Build the contents of the literal
+        literal = [pytree.Leaf(token.LBRACE, "{")]
+        literal.extend(n.clone() for n in items.children)
+        literal.append(pytree.Leaf(token.RBRACE, "}"))
+        # Set the prefix of the right brace to that of the ')' or ']'
+        literal[-1].set_prefix(items.get_next_sibling().get_prefix())
+        maker = pytree.Node(syms.dictsetmaker, literal)
+        maker.set_prefix(node.get_prefix())
+
+        # If the original was a one tuple, we need to remove the extra comma.
+        if len(maker.children) == 4:
+            n = maker.children[2]
+            n.remove()
+            maker.children[-1].set_prefix(n.get_prefix())
+
+        # Finally, replace the set call with our shiny new literal.
+        return maker