cmd/shfmt: --list exit code

[sdavids]

$ mkdir /tmp/test && cd "$_"
$ echo 'readonly  a=1' >test.sh
$ shfmt -d test.sh
diff test.sh.orig test.sh
--- test.sh.orig
+++ test.sh
@@ -1,1 +1,1 @@
-readonly  a=1
+readonly a=1
$ echo $?
1
$ shfmt -l test.sh
test.sh
$ echo $?
0

-l/--list should also return 1.

If you consider it a breaking API change you might want to introduce --set-exit-if-changed like google-java-format.

[sdavids]

The use case would be:

shfmt --list $PWD >/dev/null

vs .

shfmt --diff $PWD >/dev/null

in a Git pre-commit hook.

Currently only shfmt --diff $PWD >/dev/null works.

With --list the workaround would be something like:

diff="$(shfmt --list $PWD)"
if [ -z "${diff}" ]; then
  exit 0
else
  exit 1
fi

---

--list is faster than --diff and produces less I/O to throw away.

[mvdan]

There is some precedent with --diff using status codes; the diff tool does so, and gofmt -d will start doing this too very soon.

There is less precedent with --list that I'm aware of, and I'm a bit worried about breaking users with the reasonable use case of listing unformatted files, but who don't want to treat the presence of them as a failure. They likely are still interested in existing failures such as invalid syntax, so ignoring the status code entirely is not a good solution.

Personally, I think the "is empty" solution is good enough. It's pretty easy to do in shell and other programming languages.

[mvdan]

I'm going to close this as "won't fix" for now given the reasoning I gave above.