A space following a CSS escape sequence should be ignored

[andrew-skybound]

p {
  color: to-upper-case("ab\63 d");
}

Ruby sass

p {
  color: "ABCD";
}

Libsass

p {
  color: "ABC D";
}

The Ruby implementation follows the CSS specification, which allows a single space after an escape code to be ignored so that if the following character is a hexadecimal character, it will not affect the escaping.

Escaping is also handled incorrectly for unquoted strings.

p {
  color: to-upper-case(ab\63 d);
}

Ruby sass

p {
  color: ABCD;
}

Libsass

/* argument `$string` of `to-upper-case($string)` must be a string */

In this case, it appears that Libsass is parsing ab\63 d as a list of two strings, instead of a single unquoted string.

[xzyfer]

Spec added sass/sass-spec#464

[mgreter]

From https://drafts.csswg.org/css-syntax-3/

Consume as many hex digits as possible, but no more than 5. Note that this means 1-6 hex digits have been consumed in total. If the next input code point is whitespace, consume it as well.

[xzyfer]

Fixed in 3.3