[Feature request] Add support for checking format

[amiralies]

This would be useful to add an option either to bsc or bsb to check if files are correctly formated for rescript and reason syntax.
It can take a glob or grab files directly from sources in bsconfig. This is super useful to check format in CI.

prior art:

cargo fmt -- --check # Rust
prettier --check # Prettier
scalafmt --check # Scala

[stale]

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[dfalling]

I would love for this to happen, please don't close it bot. This feels like a pretty basic feature for a formatter.

I do this currently in my project with this script:

#!/bin/bash

files=`ls src/**/*.res src/*.res`
errors=false
for file in $files
do
  current=`cat $file`
  linted=`echo "${current}" | ./node_modules/.bin/rescript format -stdin .res`
  diff=`diff <(echo $current) <(echo $linted)`

  if [ ${#diff} -gt 0 ]
  then
    echo "ERROR: $file doesn't pass lint"
    errors=true
  fi
done

if $errors
then
  exit 1
else
  echo "All files pass linting!"
fi

[cristianoc]

This shouldn't be hard to do. PRs welcome.

[TheSpyder]

@dfalling while we wait for a fix, there's a much easier way to achieve CI failures for unformatted code - if you're in a git project:

• rescript format -all
• git diff --quiet || ((echo "Formatting check failed on the following files:"; git status --porcelain); false)

I've been using this technique for years, I just rely on git to tell me if files changed after formatting every file :)

[dfalling]

@TheSpyder oh nice trick! Have you ever hit issues where the formatter somehow broke the code for future CI steps? It's been years for me since I've had an issue so I imagine this is quite safe.

[TheSpyder]

@dfalling no, my builds fail the moment the formatter has made any changes :)

Given that I format on save, if there was an issue where the CI formatter broke the code I'm sure it would get picked up locally before trying to build with the new compiler version.

[github-actions]

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[tsnobip]

got fixed by #5760