Less CSS Preprocess module not working with advagg

The diff does show it quite well; thanks for taking the time to do that :)

Thinking that inside the advagg.inc file around line 1,000 I would change this

  // Fix for things like LESS which write dynamically to the public file system.
  $scheme = file_uri_scheme($new_filename);
  if ($scheme) {
    $wrapper = file_stream_wrapper_get_instance_by_scheme($scheme);
    if ($wrapper) {
      // Use the wrappers directory path.
      $new_filename = $wrapper->getDirectoryPath() . '/' . file_uri_target($new_filename);
    }
    else {
      // If the scheme does not have a wrapper; prefix file with the scheme.
      $new_filename = $scheme . '/' . file_uri_target($new_filename);
    }
  }

to this (only top 3 lines changed)

  // Fix for things like LESS which write dynamically to the public file system.
  $scheme = file_uri_scheme($new_filename);
  $ext = strtolower(pathinfo($path, PATHINFO_EXTENSION));
  if ($scheme && $ext === 'css') {
    $wrapper = file_stream_wrapper_get_instance_by_scheme($scheme);
    if ($wrapper) {
      // Use the wrappers directory path.
      $new_filename = $wrapper->getDirectoryPath() . '/' . file_uri_target($new_filename);
    }
    else {
      // If the scheme does not have a wrapper; prefix file with the scheme.
      $new_filename = $scheme . '/' . file_uri_target($new_filename);
    }
  }

Going back to the original issue and it has to do with the .less file having more than 4095 selectors in it. Looks like I need to install the module and create a big less file to truly fix this

Can you test this out?

Looking into this more and I think it has to do with the less 3.x vs 4.x code; playing around with hook_element_info_alter now.

fairly certain that this will fix it. Think you'll have to cc all to test.

Issue was independent from #2412093: IE CSS Selectors limiter doesn't work with less module; the other changes are there to ensure that .less files are treated like css files.

I appreciate a good bug report; makes fixing it a lot simpler!

Silly testbot; patch has already been applied.

Try disabling the IE 4095 fix in advagg. I think it is related.

Any steps to reproduce the new bug?

Is the compiled less file gets deleted, could that cause the issue you've been having?

http://cgit.drupalcode.org/less/tree/less.module#n240 - Look for less_clear_css_cache();

It call this
https://api.drupal.org/api/drupal/includes!common.inc/function/drupal_de...
which will remove any file if it was modified more than 30 days ago.

This function only gets used for core's css/js aggregation. I would increase this variable. AdvAgg piggybacks on this variable; thinking it should be independent now. You can change this under Cron Options under "Delete aggregates accessed/modified more than a set time ago." should be 1 month by default.

You'd have to remove the generated less files manually in order to see if it's the issue. The function will only delete the file after it's older than 30 days.

Hmmm so it sounds like that is not the issue as the files do get regenerated.

I'll set this to needs more info for now.

Any news on this?