[libcxx][lit] Simplify parsing of trailing executor arguments

[arichardson]

Summary

Adding a positional argparse.ONE_OR_MORE arguments will correctly remove
the "--" separator after --env and parse only the command. This also has
the advantage that misspelled flags raise an argparse error rather than
silently being added to the command to be executed.

I discovered this while adding a new commandline option to ssh.py to allow
passing additional arguments to the scp/ssh commands since this is required
for our CHERI CI where we need to pass -F <custom_config_file> to each
ssh/scp command to set various arguments such as the localhost port, usage
of controlmaster, etc. to speed up connections to our emulated QEMU systems.

[ldionne]

That's a nice cleanup! Only a nitpick.

libcxx/utils/run.py

25–26

No need for the comment anymore.

[arichardson]

remove unnecessary code now that argparse checks that at least one command argument is present

[ldionne]

Do you have commit access? If not, please specify the Author Name <[e-mail]> I should use.

[arichardson]

In D84096#2162313, @ldionne wrote:

Do you have commit access? If not, please specify the Author Name <[e-mail]> I should use.

Yes, I do. Will commit shortly.

[arichardson]

I noticed that llvm/libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.timedmutex.requirements/thread.timedmutex.class/lock.pass.cpp failed after my commit, but it seems to me that this test (and all the others in that directory) should not be assuming that the wait will be less than x milliseconds. I believe I worked around this in our CHERI fork by increasing the timeout for slow emulated systems, but that could still fail in some cases.

libcxx/utils/run.py

 import subprocess
 import sys
 
 
 def main():
     parser = argparse.ArgumentParser()
     parser.add_argument('--execdir', type=str, required=True)
     parser.add_argument('--codesign_identity', type=str, required=False, default=None)
     parser.add_argument('--env', type=str, nargs='*', required=False, default=dict())
-    (args, remaining) = parser.parse_known_args(sys.argv[1:])
-
-    if len(remaining) < 2:
-        sys.stderr.write('Missing actual commands to run')
-        exit(1)
-    commandLine = remaining[1:] # Skip the '--'
+    parser.add_argument("command", nargs=argparse.ONE_OR_MORE)
+    args = parser.parse_args()
+    commandLine = args.command
 
     # Do any necessary codesigning.
     if args.codesign_identity:
         exe = commandLine[0]
         rc = subprocess.call(['xcrun', 'codesign', '-f', '-s', args.codesign_identity, exe], env={})
         if rc != 0:
             sys.stderr.write('Failed to codesign: ' + exe)
             return rc

libcxx/utils/ssh.py

 
 
 def main():
     parser = argparse.ArgumentParser()
     parser.add_argument('--host', type=str, required=True)
     parser.add_argument('--execdir', type=str, required=True)
     parser.add_argument('--codesign_identity', type=str, required=False, default=None)
     parser.add_argument('--env', type=str, nargs='*', required=False, default=dict())
-    (args, remaining) = parser.parse_known_args(sys.argv[1:])
-
-    if len(remaining) < 2:
-        sys.stderr.write('Missing actual commands to run')
-        return 1
-
-    commandLine = remaining[1:] # Skip the '--'
+    parser.add_argument("command", nargs=argparse.ONE_OR_MORE)
+    args = parser.parse_args()
+    commandLine = args.command
 
     ssh = lambda command: ['ssh', '-oBatchMode=yes', args.host, command]
     scp = lambda src, dst: ['scp', '-q', '-oBatchMode=yes', src, '{}:{}'.format(args.host, dst)]
 
     # Create a temporary directory where the test will be run.
     # That is effectively the value of %T on the remote host.
     tmp = subprocess.check_output(ssh('mktemp -d /tmp/libcxx.XXXXXXXXXX'), universal_newlines=True).strip()