Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.3.14)
// Compass (v1.0.1)
// ----

/*
  LINE 20 - CHECKING & SETTING MAPS FAILS IN 3.4.x
*/

$mixin-denominator-numbers:               (1 2 3) !default;
$_percentage-class-instances:             () !default;

@mixin generate-percentage-classes() {
  @each $denominator in $mixin-denominator-numbers {
      
    $selector: ".u-#{$denominator * 100}pc";
    
    @if (map-has-key($_percentage-class-instances, $selector)) {
      $_percentage-class-instances: map-merge($_percentage-class-instances, ($selector: 2));
    }
    @else {
      $_percentage-class-instances: map-merge($_percentage-class-instances, ($selector: 1));
    }
    
    @if (map-get($_percentage-class-instances, $selector) == 1) {
      #{$selector} {
        width: percentage($denominator);
      }
    }
  }
}

@include generate-percentage-classes();

SassMeister-output.css

/*
  LINE 20 - CHECKING & SETTING MAPS FAILS IN 3.4.x
*/
.u-100pc {
  width: 100%;
}

.u-200pc {
  width: 200%;
}

.u-300pc {
  width: 300%;
}