Compress will break calc when use 0px

[NE-SmallTown]

Hi, I'm using a loader which would set the compress option in production mode. But in the production mode, less will do this:

https://github.com/less/less.js/blob/b8140d4baad18ba732e2b322d8891a9b0ff065d5/lib/less/tree/dimension.js#L43-L54

if (context && context.compress) {
    // Zero values doesn't need a unit
    if (value === 0 && this.unit.isLength()) {   //    <<<<<<<<<<<------ see here
        output.add(strValue);
        return;
    }

    // Float values doesn't need a leading zero
    if (value > 0 && value < 1) {
        strValue = (strValue).substr(1);
    }
}

So, if I use something like:
calc(0px + 1rem + 2rem)
it will output:
calc(0 + 1rem + 2rem)
which will make the css broken in production mode.

Yea, why I don't just use calc(1rem + 2rem)? That's because this is just an example, actually I use calc(@offset - env(safe-area-inset-bottom)) in my less file(@offset will be 0 sometimes).

So, is this a bug? IMO, we could don't remove the unit(i.e. 'px') when in the calc expression but I'm not familiar with the less codebase.

[matthew-dean]

The compress option is deprecated. So I'm not sure if it's worth setting a priority for this edge case, if it will be removed eventually.

[NE-SmallTown]

Yea, but I can't control the option setting because the 3rd party loader does it. So I think fix this case may be useful

[seven-phases-max]

because the 3rd party loader does it.

Then this is a just bug in that 3rd party loader that should be fixed there. The compress option was marked as deprecated more than 3.5 years ago specifically because there's no way to fix it (simply because the way it was designed and implemented is fundamentally incompatible with the current CSS state/features).

---

Either way the solution I would propose would be just to kill this and similar lines everywhere so that no if (... context.compress) { ... branches are triggered anymore. In other words, the context.compress value should always be kept false until all the code (it's a lot) using this value is removed.

[NE-SmallTown]

Thanks for your clarification! Sure, the loader should fix this but before I just mean it will do some work to do that, but if we could fix this(as you suggested just set it to false in less codebase), the loader could just update the version and fix it later

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.