interpolation of strings in idents is literal

src/utils.rs

@@ -525,9 +525,10 @@ pub(crate) fn eat_ident<I: Iterator<Item = Token>>(
         if kind == &'{' {
             toks.next();
             text.push_str(
-                &parse_interpolation(toks, scope, super_selector)?
-                    .node
-                    .to_css_string(span)?,
+                &match parse_interpolation(toks, scope, super_selector)?.node {
+                    Value::Ident(s, ..) => s,
+                    v => v.to_css_string(span)?,
+                },
             );
         } else {
             return Err(("Expected identifier.", *pos).into());

src/value/mod.rs

@@ -165,14 +165,10 @@ impl Value {
                 let mut buf = String::with_capacity(string.len());
                 for c in string.chars() {
                     match c {
-                        // TODO: figure out what is going on here
-                        // This is adapted from the original dart-sass
-                        // code, but in the spec tests it seems that
-                        // newlines are not actually treated like this.
-                        // '\n' => {
-                        //     buf.push(' ');
-                        //     after_newline = true;
-                        // }
+                        '\n' => {
+                            buf.push(' ');
+                            after_newline = true;
+                        }
                         ' ' => {
                             if !after_newline {
                                 buf.push(' ');

tests/interpolation.rs

@@ -53,3 +53,8 @@ test!(
     "a {\n  color: \"#{#{\"\\a\"}}\";\n}\n",
     "a {\n  color: \"\\a\";\n}\n"
 );
+test!(
+    interpolated_quoted_newline,
+    "a {\n  color: #{\"\\a\"};\n}\n",
+    "a {\n  color:  ;\n}\n"
+);