parser: Fix crash on non-ASCII char literals

If the given char literal was not an ASCII one, there was the chance for
the character iterator to mess things up. Hence, when checking the
closing single quote, it might encounter a None value.

This is simply mitigated my moving the check of ASCII alphanumeric
before checking for the closing quote.

Fixes: b1623996c76f ("Add support for character literals")

Signed-off-by: Miquel Sabaté Solà <mikisabate@gmail.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/lib/xixanta/src/parser.rs b/lib/xixanta/src/parser.rs
index 9c67587..19b4530 100644
--- a/lib/xixanta/src/parser.rs
+++ b/lib/xixanta/src/parser.rs
@@ -789,14 +789,14 @@ impl Parser {
         let del = chars.next().unwrap();
         let ch = chars.next().unwrap();
 
-        if del != '\'' || chars.next().unwrap() != '\'' {
-            return Err(self.parser_error("bad character literal"));
-        }
         if !ch.is_ascii_alphanumeric() {
             return Err(self.parser_error(
                 "only alphanumeric ASCII characters are allowed on character literals",
             ));
         }
+        if del != '\'' || chars.next().unwrap() != '\'' {
+            return Err(self.parser_error("bad character literal"));
+        }
 
         Ok(PNode {
             node_type: NodeType::Literal,