Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.3.4)
// Compass (v1.0.0.alpha.18)
// ----

// in module A
.featureA {
  %placeholderA {
    content: 'A';
  }
}

.featureB .thing {
    @extend %placeholderA;
}

SassMeister-output.css

.featureA .featureB .thing, .featureB .featureA .thing {
  content: 'A';
}