Value is not calculated for css --variables about less.js HOT 2 CLOSED

Maybe this bug should be about lack of documentation then? I tried to look this up and found nothing.

from less.js.

This is by design and not a bug. For example, let's say you had this:

.test {
  --width: 20px + foo({ 40: 'px' });
}

What should Less do with this? The value you have for --width is 100% perfectly valid, and you could be intending to evaluate it as JavaScript, so it couldn't throw an error as an invalid expression. Instead, you have to evaluate it before-hand:

.test {
  @width: 20px + 40px;
  --width: @width;
}

Less evaluating at-rules in custom properties has its own add-in side-effects / bugs, but that's what is currently supported.

from less.js.