Add check for input import before running FixInput

src/libfuturize/fixes/__init__.py

@@ -50,7 +50,7 @@
     'lib2to3.fixes.fix_getcwdu',
     # 'lib2to3.fixes.fix_imports',   # called by libfuturize.fixes.fix_future_standard_library
     # 'lib2to3.fixes.fix_imports2',  # we don't handle this yet (dbm)
-    'lib2to3.fixes.fix_input',
+    # 'lib2to3.fixes.fix_input',     # Called conditionally by libfuturize.fixes.fix_input
     'lib2to3.fixes.fix_itertools',
     'lib2to3.fixes.fix_itertools_imports',
     'lib2to3.fixes.fix_filter',
@@ -86,6 +86,7 @@
     'libfuturize.fixes.fix_future_builtins',
     'libfuturize.fixes.fix_future_standard_library',
     'libfuturize.fixes.fix_future_standard_library_urllib',
+    'libfuturize.fixes.fix_input',
     'libfuturize.fixes.fix_metaclass',
     'libpasteurize.fixes.fix_newstyle',
     'libfuturize.fixes.fix_object',

src/libfuturize/fixes/fix_input.py

@@ -0,0 +1,32 @@
+"""
+Fixer for input.
+
+Does a check for `from builtins import input` before running the lib2to3 fixer.
+The fixer will not run when the input is already present.
+
+
+this:
+    a = input()
+becomes:
+    from builtins import input
+    a = eval(input())
+
+and this:
+    from builtins import input
+    a = input()
+becomes (no change):
+    from builtins import input
+    a = input()
+"""
+
+import lib2to3.fixes.fix_input
+from lib2to3.fixer_util import does_tree_import
+
+
+class FixInput(lib2to3.fixes.fix_input.FixInput):
+    def transform(self, node, results):
+
+        if does_tree_import('builtins', 'input', node):
+            return
+
+        return super(FixInput, self).transform(node, results)

tests/test_future/test_futurize.py

@@ -436,6 +436,27 @@ def test_import_builtins(self):
         """
         self.convert_check(before, after, ignore_imports=False, run=False)
 
+    def test_input_without_import(self):
+        before = """
+        a = input()
+        """
+        after = """
+        from builtins import input
+        a = eval(input())
+        """
+        self.convert_check(before, after, ignore_imports=False, run=False)
+
+    def test_input_with_import(self):
+        before = """
+        from builtins import input
+        a = input()
+        """
+        after = """
+        from builtins import input
+        a = input()
+        """
+        self.convert_check(before, after, ignore_imports=False, run=False)
+
     def test_xrange(self):
         """
         The ``from builtins import range`` line was being added to the