Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.9)
// Compass (v1.0.1)
// ----

$m : '.m-foo';

// Currently

#{$m} {
  color: blue;
  #{$m}__bar {
    color: red;
  }
}

// With Sass 3.4

#{$m} {
  color: blue;
  &__bar {
    color: red;
    &-baz {
      color: green;
    }
  }
}

SassMeister-output.css

.m-foo {
  color: blue;
}
.m-foo .m-foo__bar {
  color: red;
}

.m-foo {
  color: blue;
}
.m-foo__bar {
  color: red;
}
.m-foo__bar-baz {
  color: green;
}