DEPRECATION WARNING: Passing a string to call() is deprecated and will be illegal in Sass 4.0. Use call(get-function("output-isolation")) instead.

[architarious]

If you've upgraded to Sass 3.5.0 or higher you're likely getting this warning every time you try to compile something using the grid-span mixin. More information for why this warning exists is available in the Sass Changelog and in this article.

In order to get rid of it you need to wrap the function call with get-function().

Go to lines 58 through 64 on singulairtygs/_api.scss and change:

@if $Direction == 'both' or $From == 'left' or ($Direction == 'rtl' and $From == 'opposite') {
      $Left: call('output-#{$output-style}', map-merge($Span-Map, ('direction': left)));
    }
@if $Direction == 'both' or $From == 'right' or ($Direction == 'ltr' and $From == 'opposite') {
      $Right: call('output-#{$output-style}', map-merge($Span-Map, ('direction': right)));
 }

to

@if $Direction == 'both' or $From == 'left' or ($Direction == 'rtl' and $From == 'opposite') {
      $Left: call(get-function('output-#{$output-style}'), map-merge($Span-Map, ('direction': left)));
    }
 @if $Direction == 'both' or $From == 'right' or ($Direction == 'ltr' and $From == 'opposite') {
      $Right: call(get-function('output-#{$output-style}'), map-merge($Span-Map, ('direction': right)));
   }

[altrugon]

It seems like this project has been abandoned by its author, technology moves fast so it's understandable.

Here is my solution which will work on every npm install.

1. Install patch-package.
   npm i patch-package
2. Edit the singulairtygs/_api.scss as mentioned by @architarious on the description of this issue and save that file.
3. Add the postinstall script to your package.json as followed:

"scripts": {
  "postinstall": "patch-package"
 }

4. Create the patch by running the following command:
   npm run postinstall singularitygs
5. Once the command has been finished you should have a patches folder, inside it is your patch.
6. Since postinstall is an NPM script it will apply your patch after every npm install, the only thing left is add it to your repo and commit it.

If you need extra test before committing, delete node_modules and run npm install, then check the patch has been applied to the file.

[scottkellum]

Keeping this open and locked so that others can see