&& support

Source

.foo {
    &&_bar:hover {
        color: red;
    }
}

Result

Invalid CSS after "&": expected "{", was "&_bar:hover"

"&_bar:hover" may only be used at the beginning of a compound selector.

Expected

.foo.foo_bar:hover {
    color: red;
}

[cimmanon]

You can already do this.

.foo {
    &#{&}_bar:hover {
        color: red;
    }
}

[LiHongxiang1993]

.foo { &#{&}_bar:hover { color: red; } }
worked for me! wonderful!