Is it a really issue if you ask Autoprefixer to remove old prefix? ;)

@ai How to preserve -webkit-box-orient?

Add any flexbox 2009 browser to browserslist in your package.json.

Thank you

@ai This still happens even if I add remove: false to the options.

Are you sure that it does from Autoprefixer? Maybe some other tool (like minification in webpack’s css-loader) change file too?

tested out with css-loader remain the same version, Autoprefixer is the only factor remains that causing this

Oh, I was passing remove:false to postcss-cssnext. Passing it on to autoprefixer results in -webkit-box-orient not being removed.

var postcss = require('postcss');

var css = postcss([
  require('postcss-cssnext')({
    browsers: 'chrome >= 42, safari >= 8',
    features: {
      autoprefixer: {remove: false}
    }
  })
]).process(`
.foo {
  display: -webkit-box;
  -webkit-box-orient: vertical;
  -webkit-box-align: stretch;
}`).css;

console.log(css);

I thought the behavior of the (default) remove:true option was to only remove outdated rules if the modern rule was specified too. So that display:-webkit-flex;display:flex; -> display:flex; if possible, but display:-webkit-flex; alone would remain as display:-webkit-flex;. This case still seems to be the same. The -webkit-box-orient rules uniquely being stripped unconditionally is surprising to me, and I wonder if it really is intended or best given that it doesn't seem any other rules are treated like that.

Disabling the remove option or adding a flexbox 2009 browser to browsers list are both fairly coarse workarounds for this type of scenario. Any interest in adding an option to opt-out of removal at the rule level?

Extra option is not a solution, because most of developers will not read docs.

If you want to fix it, send a PR removing this hack
https://github.com/postcss/autoprefixer/blob/master/lib/processor.coffee#L133

@ai thanks - will do

Possibly helpful for anyone reading up on this thread and problem, least intrusive option to prevent the removal of the line in question is to just disable the autoprefixer for this line/section

    /* autoprefixer: off */
    -webkit-box-orient: vertical;
    /* autoprefixer: on */

@Lars-Weber best option is just add old Safari to browserslist config