Windows: backslashes passed to subprocess are unnecessarily unescaped.

Please provide the following information. The more we know about your system and use case, the more easily and likely we can help.

Description of the problem / feature request / question:

I am running the generated .exe file of a py_binary, which is a data deps of another py_test. The backslashes in the arguments passed to the .exe file end up unnecessarily unescaped in the py_binary.

If possible, provide a minimal example to reproduce the problem:

BUILD:

py_binary(
    name = "sub",
    srcs = ["sub.py"],
)
py_test(
    name = "main",
    srcs = ["main.py"],
    data = [":sub"],
)

main.py:

import os
import subprocess
import unittest
class MainTest(unittest.TestCase):
  def testMain(self):
    test_srcdir = os.getenv('TEST_SRCDIR')
    with open(os.path.join(test_srcdir, 'MANIFEST'), 'r') as f:
      for line in f:
        tokens = line.strip().split(' ')
        if len(tokens) == 2 and tokens[0] == '__main__/sub.exe':
          sub_path = tokens[1]
          break
    subprocess.check_call([sub_path, r'path\to\dir'])
if __name__ == '__main__':
  unittest.main()

sub.py:

import sys
if sys.argv[1] != r'path\to\dir':
  raise RuntimeError('Unexpected sys.argv[1]: {}\n'.format(sys.argv[1]))

bazel test :main fails, because sys.argv[1] is actually r'path\\to\\dir' instead of r'path\to\dir'.

Environment info

• Operating System: Windows Server 2016

• Bazel version (output of bazel info release): release 0.7.0

[meteorcloudy]

Just sent a fix to review: https://bazel-review.googlesource.com/#/c/bazel/+/26710/

[meteorcloudy]

@yilei Sorry for the delay. @laszlocsomor Sure, I can take over. 😉