xonsh default shell doesn't accept sh syntax

[eugenesvk]

If I set xonsh as my default login shell in WSL2, then I can't use wslbridge2 anymore due to incompatible syntax (the bridge only prepares the sh-syntax command), instead I get the following error:

Backend CommandLine: "C:\WINDOWS\System32\wsl.exe" /bin/sh -c 'exec "$(wslpath -u '\''C:\path\to\wslbridge2-backend'\'')" --login --show --cols 120 --rows 30 -060266 -149859 -359317 -- /home/linuxbrew/.linuxbrew/bin/xonsh'

Traceback

X=/home/linuxbrew/.linuxbrew/Cellar/xonsh/0.10.1/libexec/lib/python3.9/site-packages (shortened for readability)

Traceback (most recent call last):
    _failback_to_other_shells(args, err)    run_code_with_cache(
  File "X/xonsh/__amalgam__.py", line 3328, in run_code_with_cache
    tree = self.parser.parse(
  File "X/xonsh/parsers/base.py", line 523, in parse
    tree = self.parser.parse(input=s, lexer=self.lexer, debug=debug_level)
  File "X/xonsh/ply/ply/yacc.py", line 335, in parse
    return self.parseopt_notrack(input, lexer, debug, tracking, tokenfunc)
  File "X/xonsh/ply/ply/yacc.py", line 1203, in parseopt_notrack
    tok = call_errorfunc(self.errorfunc, errtoken, self)
  File "X/xonsh/ply/ply/yacc.py", line 194, in call_errorfunc
    r = errorfunc(token)
  File "X/xonsh/parsers/base.py", line 3459, in p_error
    self._parse_error(msg, self.currloc(lineno=p.lineno, column=p.lexpos))
  File "X/xonsh/parsers/base.py", line 650, in _parse_error
    raise_parse_error(msg, loc, self.xonsh_code, self.lines)
  File "X/xonsh/parsers/base.py", line 238, in raise_parse_error
    raise err

SyntaxError: 080d92d8c20c62294b20abf38050b6da:1:0: ('code: /',)
/bin/sh -c 'exec "$(wslpath -u '\''C:\path\to\wslbridge2-backend'\'')" --login --show --cols 120 --rows 30 -060266 -149859 -359317 -- /home/linuxbrew/.linuxbrew/bin/xonsh'
^

The proper command for this should be something like (newline-split for readability)

"C:\WINDOWS\System32\wsl.exe"
/bin/sh -c
@("exec '{bridge}' {args}".format(
  bridge=$(wslpath -u r"C:\path\to\wslbridge2-backend").rstrip(),
  args="--show --cols 120 --rows 30 -060266 -149859 -359317 -- /home/linuxbrew/.linuxbrew/bin/xonsh"
  ) )

I'll submit a PR shortly that introduces the new syntax either via the less convenient command-flag or via the auto-detection of the default shell via grep "^$(id -un)": /etc/passwd
(I bypassed the appendWslArg function as there is no need to escape the quotes, and I don't understand how relevant the other corrections are :))

[Biswa96]

xonsh default shell doesn't accept sh syntax

Isn't this a problem of xonsh?

[eugenesvk]

xonsh default shell doesn't accept sh syntax

Isn't this a problem of xonsh?

of course not, why would you expect it to accept incorrect syntax?

[Biswa96]

If you don't mind I would like to investigate on this. I am not against this. I want to just explore things first.

[eugenesvk]

Sure thing, maybe you'll find out a nifty trick to make xonsh accept the syntax (with a few more '\'' ;) )!

I think it's mainly the $(wslpath -u substitution that breaks it, so maybe if you do the path conversion internally and switch \ to / it'll be fine, at least
"C:\WINDOWS\System32\wsl.exe" /bin/sh -c 'exec "/mnt/c/path/to/wslbridge2-backend" --help'
doesn't throw any syntax errors and shows teh help message