gccrs: Prevent invalid iterator dereference

gcc/rust/ChangeLog:

	* lex/rust-lex.cc
	(Lexer::classify_keyword): Check if iterator is valid before dereferencing.

Signed-off-by: Owen Avery <powerboat9.gamer@gmail.com>

diff --git a/gcc/rust/lex/rust-lex.cc b/gcc/rust/lex/rust-lex.cc
index c910c7cf83adf897be7c1bdaad317206c6cad62d..23579e519443118b2dc8a6ae44536b3f1eb5a6a6 100644 (file)
--- a/gcc/rust/lex/rust-lex.cc
+++ b/gcc/rust/lex/rust-lex.cc
@@ -255,11 +255,12 @@ TokenId
 Lexer::classify_keyword (const std::string &str)
 {
   auto keyword = keywords.find (str);
-  auto id = keyword->second;
 
   if (keyword == keywords.end ())
     return IDENTIFIER;
 
+  auto id = keyword->second;
+
   // We now have the expected token ID of the reserved keyword. However, some
   // keywords are reserved starting in certain editions. For example, `try` is
   // only a reserved keyword in editions >=2018. The language might gain new