placeholder-shown selector should not be merged

CSSO automatically merges blocks with identical properties even when :placeholder-shown, :-ms-input-placeholder, :-moz-placeholder-shown are used as selectors.

Those vendor prefixed selectors are typically generated by autoprefixer (cf https://github.com/postcss/autoprefixer/issues/1311 )

But actually browsers ignores the blocks when a unrecognized selector is present.

Faulty behaviour encountered on

• chromium 81.0.4044.138 (Official Build) Built on Ubuntu , running on Ubuntu 18.04 (64-bit)
• mozilla firefox 76.0.1 (64bit) for ubuntu

For example, given two text inputs with different ids

#input1:placeholder-shown {
  background-color: green; /* applied */
}

#input1:-ms-input-placeholder {
  background-color: green;
}

#input2:placeholder-shown, #input2:-ms-input-placeholder {
  background-color: green; /* ignored */
}

related codepen : https://codepen.io/agka/pen/vYNMeBq

Possibly related to #383

Known workaround is to set restructure to false but it kinda defeats the purpose of the optimizer

[lahmatiy]

I believe it fixed in https://github.com/css/csso/commit/ba7952c7f457600f3cf7f9c844ea1509ffb89468 and will be shipped in next version.

[lahmatiy]

@agka Thank you for the report, I’ve created an issue – #450