adding --outputStyle compressed leads to semantically different css

[maxwellium]

in a mixin

@mixin flex($grow: 1, $shrink: null, $basis: null) {
  -webkit-box-flex: $grow;
  -webkit-flex: $grow $shrink $basis;
  -moz-box-flex: $grow;
  -moz-flex: $grow $shrink $basis;
  -ms-flex: $grow $shrink $basis;
  flex: $grow $shrink $basis;
}

the null params get parsed as they should producing this:

[flex] {
-webkit-flex: 1;
-moz-flex: 1;
-ms-flex: 1;
flex: 1;
}

when adding the outputStyle compressed flags however, the following output is returned

[flex] {
-webkit-flex: 1nullnull;
-moz-flex: 1nullnull;
-ms-flex: 1nullnull;
flex: 1nullnull;
}

[am11]

This would need to be fixed in libsass.

[maxwellium]

right. raised there sass/libsass#487

[am11]

👍