<===> options.yml
---
:ignore_for:
- dart-sass

<===> input.scss
@mixin spec1($decimal) {
  $decimal: unquote($decimal) * -1;
  value: $decimal;
}

@mixin spec2($decimal) {
  $decimal: -1 * unquote($decimal);
  value: $decimal;
}

@mixin spec3($decimal) {
  value: #{$decimal * -1};
}

.my-element {
  @include spec1(3);
  @include spec1(-3);
  @include spec2(5);
  @include spec2(-5);
  @include spec3(7);
  @include spec3(-7);
}
<===> output.css
.my-element {
  value: -3;
  value: 3;
  value: -5;
  value: 5;
  value: -7;
  value: 7;
}

<===> warning
DEPRECATION WARNING: Passing 3, a non-string value, to unquote()
will be an error in future versions of Sass.
        on line 2 of input.scss, in `spec1'
        from line 16 of input.scss
DEPRECATION WARNING: Passing 5, a non-string value, to unquote()
will be an error in future versions of Sass.
        on line 7 of input.scss, in `spec2'
        from line 18 of input.scss