test for crazy interpolation inside @if

src/parse/mod.rs

@@ -545,9 +545,8 @@ impl<'a> Parser<'a> {
             self.throw_away_until_closing_curly_brace()?;
         }
 
-        self.whitespace_or_comment();
-
         loop {
+            self.whitespace_or_comment();
             if let Some(Token { kind: '@', pos }) = self.toks.peek().cloned() {
                 self.toks.peek_forward(1);
                 let ident = peek_ident_no_interpolation(self.toks, false, pos)?;

src/parse/throw_away.rs

@@ -27,10 +27,14 @@ impl<'a> Parser<'a> {
                         return Err((format!("Expected {}.", q), tok.pos).into());
                     }
                 }
-                '#' => {
+                '#' => match self.toks.peek() {
+                    Some(Token { kind: '{', .. }) => {
                         self.toks.next();
                         self.throw_away_until_closing_curly_brace()?;
                     }
+                    Some(..) => {}
+                    None => return Err(("expected \"{\".", self.span_before).into()),
+                },
                 _ => {}
             }
         }

tests/if.rs

@@ -140,6 +140,29 @@ test!(
     "@mixin foo {\n    color: red;\n}\n\n@if true {\n    a {\n        @include foo;\n    }\n}\n",
     "a {\n  color: red;\n}\n"
 );
+test!(
+    crazy_interpolation,
+    "a {
+        @if true {
+            a: #{\"#{\"\\\\}}}{{{\"}#\"};
+        }
+
+        @if false {
+            a: #{\"#{\"\\\\}}}{{{\"}#\"};
+        } @else if true {
+            b: #{\"#{\"\\\\}}}{{{\"}#\"};
+        }
+
+        @if false {
+            a: #{\"#{\"\\\\}}}{{{\"}#\"};
+        } @else if false {
+            b: #{\"#{\"\\\\}}}{{{\"}#\"};
+        } @else {
+            c: #{\"#{\"\\\\}}}{{{\"}#\"};
+        }
+    }",
+    "a {\n  a: \\}}}{{{#;\n  b: \\}}}{{{#;\n  c: \\}}}{{{#;\n}\n"
+);
 error!(
     nothing_after_escape,
     "@if \\", "Error: Expected expression."