Use only safe css optimizations

[hashrocketeer]

OptimizeCSSAssetsPlugin uses a number of optimizations,
see this list.
The optimization in particular that caused us harm was
the
zindex
optimization which compresses zindex numbers (100, 200 -> 1, 2) for all
css that is processed by webpack. Not all css in a Rails app is
processed by webpack. The asset pipeline can still process stylesheets
in addition to css that is included into the code itself.

Including this css optimization into the framework was a breaking change
for us.

Co-authored-by: Chris Erin chris.erin@gmail.com
Co-authored-by: Ryan Messner rpmessner@gmail.com

[gauravtiwari]

Thanks @hashrocketeer

Makes sense, seems like option safe is removed now from the plugin: NMFR/optimize-css-assets-webpack-plugin@784677f

We might have to do something like this:

const safeParser = require('postcss-safe-parser');

new OptimizeCssAssetsPlugin({
        cssProcessorOptions: { 
          parser: safeParser,
          discardComments: {
            removeAll: true
          }
        }
      })

Could you please investigate and update the PR (if you have time)?

[chriserin]

@gauravtiwari yeah thanks for the update. I've been looking through both cssnano and OptimizeCssAssetsPlugin, but nothing jumps out to me. I'll keep looking, I have seen threads where people talk about zindex being turned off by default in cssnano but that's not the case.

[gauravtiwari]

@chriserin Hey! have you found anything on this?