Should error on selector with invalid quote mark

[xzyfer]

Discovered from #2080

Sass

$prefix: "";
$suffix: bar;
$class: $prefix#{"-"}#{$suffix};

#{$class} {
  foo: bar;
}

LibSass 3.3.6

""-bar {
  foo: bar;
}

Ruby Sass 3.4.21

Invalid CSS after "": expected selector, was """-bar"

Spec added sass/sass-spec#912

[xzyfer]

A work around for this is Interpolating $prefix because interpolation should always return an unquoted string.

$class: #{$prefix}#{"-"}#{$suffix};

Produces

-bar {
  foo: bar;
}

[xzyfer]

@nex3 can you please confirm what the expected output of this is? I'm getting contradicting results from Ruby Sass 3.4, 3.5, and 4.

$prefix: "";
$suffix: bar;
$class: $prefix#{"-"}#{$suffix};

#{$class} {
  foo: bar;
}

[nex3]

It depends if you're using the 3.X interpolation parsing scheme or the 4.0 scheme. Under 3.X, $prefix#{"-"}#{suffix} converts $prefix to a string (in this case, the unquoted string containing two double quote characters) and concatenates it with the string -bar. Under 4.0, the fact that the $prefix variable is next to #{"-"}#{$suffix} doesn't matter, so it's instead parsed as a list containing two values: an empty quoted string and the unquoted string -bar.

Don't forget I wrote up a whole thing about interpolation parsing in sass/sass#1778.