parse selectors that grow larger from interpolation

src/selector/mod.rs

@@ -285,13 +285,7 @@ impl Selector {
 
         let mut sel_toks = Vec::new();
 
-        let mut current_pos = 0;
+        sel_toks.extend(string.chars().map(|x| Token::new(span, x)));
-        sel_toks.extend(string.chars().map(|x| {
-            let len = x.len_utf8() as u64;
-            let tok = Token::new(span.subspan(current_pos, current_pos + len), x);
-            current_pos += len;
-            tok
-        }));
 
         let mut iter = sel_toks.into_iter().peekmore();
 

tests/selectors.rs

@@ -512,3 +512,11 @@ test!(
     "\\61 {\n    color: red;\n}\n",
     "a {\n  color: red;\n}\n"
 );
+/// this checks for a bug in which the selector
+/// contents get longer as a result of interpolation,
+/// which interferes with span information.
+test!(
+    selector_span_gets_larger,
+    "$a: aaaaaaaaaaa;\n\n#{$a} {\n    color: foo;\n}\n",
+    "aaaaaaaaaaa {\n  color: foo;\n}\n"
+);