Add a test for escaping of backslashes in list expansion

pylib/gyp/input.py

 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 from compiler.ast import Const
 from compiler.ast import Dict
 from compiler.ast import Discard
 from compiler.ast import List
 from compiler.ast import Module
 from compiler.ast import Node
@@ skipping 718 matching lines @@
 
       if expand_to_list:
         # Expanding in list context.  It's guaranteed that there's only one
         # replacement to do in |input_str| and that it's this replacement.  See
         # above.
         if isinstance(replacement, list):
           # If it's already a list, make a copy.
           output = replacement[:]
         else:
           # Split it the same way sh would split arguments.
-          output = shlex.split(str(replacement))
+          output = shlex.split(str(replacement).replace('\\', '\\\\'))

[Mark Mentovai, 2011/12/14 17:53:54]

Are you sure that this is right? Seems perverse. The backslash is very special
and this doesn’t account for all possibilities, like backslashes inside
single-quoted strings.
['ab', 'c', 'd\\e']
['a\\b', 'c', 'd\\\\e']

That’s kind of weird, don’t you agree?

[tony, 2011/12/14 18:41:39]

Backslash is only special when being passed to a command line.  This is just
variable expansion.  Shouldn't the special handling of backslash in single
quotes be handled when executing the command?

It's more weird that we escape backslash in list expansion, but not in non-list
expansion.

       else:
         # Expanding in string context.
         encoded_replacement = ''
         if isinstance(replacement, list):
           # When expanding a list into string context, turn the list items
           # into a string in a way that will work with a subprocess call.
           #
           # TODO(mark): This isn't completely correct.  This should
           # call a generator-provided function that observes the
           # proper list-to-argument quoting rules on a specific
@@ skipping 1596 matching lines @@
     ValidateRunAsInTarget(target, target_dict, build_file)
     ValidateActionsInTarget(target, target_dict, build_file)
 
   # Generators might not expect ints.  Turn them into strs.
   TurnIntIntoStrInDict(data)
 
   # TODO(mark): Return |data| for now because the generator needs a list of
   # build files that came in.  In the future, maybe it should just accept
   # a list, and not the whole data dict.
   return [flat_list, targets, data]