🚀 Flag to suppress the non-zero exit code

[SigmaSquadron]

Hi! I'm using delta as a diff viewer for Jujutsu, and jj warns the user if the diff program exits in a non-zero exit code. Would it be acceptable to add a flag to suppress the exit code when there is a diff?

[th1000s]

What command do you or jj call, and what input does it get? Diffs usually return a non-zero exit code, maybe adding || true to it can help?

[SigmaSquadron]

jj calls it with something along the lines of delta <flags> <dir1> <dir2> There must be some weird shell escaping, quoting or word splitting (or lack thereof) going on, because || true is parsed as a directory name:

$ jj diff
delta> error: unexpected argument '||' found
delta>
delta> Usage: delta [OPTIONS] [MINUS_FILE] [PLUS_FILE]

Here's the jj log when delta is called normally:

$ jj diff --debug
INFO run_command:cmd_diff: jj_cli::merge_tools::external: Invoking the external diff generator: cmd="/nix/store/jaiid8gc746wsmf48pgaxc0x0j2xy8l5-delta-0.18.2/bin/delta" "--color-only" "--diff-so-fancy" "--navigate" "--side-by-side" "--line-numbers" "/tmp/jj-diff-4GBaTW/left" "/tmp/jj-diff-4GBaTW/right"
INFO run_command:cmd_diff: jj_cli::merge_tools::external: The external diff generator exited: cmd="/nix/store/jaiid8gc746wsmf48pgaxc0x0j2xy8l5-delta-0.18.2/bin/delta" "--color-only" "--diff-so-fancy" "--navigate" "--side-by-side" "--line-numbers" "/tmp/jj-diff-4GBaTW/left" "/tmp/jj-diff-4GBaTW/right" exit_status=ExitStatus(unix_wait_status(256))
Warning: Tool exited with exit status: 1 (run with --debug to see the exact invocation)

[th1000s]

I see, jj doesn't do simple shell invocation, you would have to write you own wrapper, like delta "$@"; true in e.g. delta_jj.sh

Also, the comment here in merge_tools/external.rs and the debug output somewhat disagree:

    // Non-zero exit code isn't an error. For example, the traditional diff command
    // will exit with 1 if inputs are different.

And delta specifically does 0 / 1 / 2 for same / different / actually-an-error.

Is is only in the debug output, or does this bubble up to the shell?

[SigmaSquadron]

The Warning: Tool exited with exit status: 1 (run with --debug to see the exact invocation) message does appear without --debug. Could be that this is a configuration issue with jj somehow.

[th1000s]

Okay, in this case the jj diff handling is still incomplete, as the comment there suggests. This warning should only be printed on >= 2 exit status. Plain git diff --no-index or even diff -u have the same exit status as delta. Please file an issue there :)

[tschundler]

jj has a config to ignore certain error codes on call to diff visualizer:

[ui]
diff-formatter = "delta"

[merge-tools.delta]
diff-expected-exit-codes = [0, 1]

(for anyone else landing here)