From 1fcea5fb03ffe701c8eac1575cac64afd49f9e8f Mon Sep 17 00:00:00 2001
From: chrchr-github <78114321+chrchr-github@users.noreply.github.com>
Date: Tue, 7 Feb 2023 22:36:42 +0100
Subject: [PATCH] Don't crash on C++23 code (#4771)

---
 lib/tokenlist.cpp     | 2 +-
 test/testtokenize.cpp | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/lib/tokenlist.cpp b/lib/tokenlist.cpp
index 87cd9b9dc..0e72ce2c6 100644
--- a/lib/tokenlist.cpp
+++ b/lib/tokenlist.cpp
@@ -1598,7 +1598,7 @@ static Token * createAstAtToken(Token *tok, bool cpp)
                 semicolon2->astOperand2(state3.op.top());
             semicolon1->astOperand2(semicolon2);
         } else {
-            if (!cpp || !Token::simpleMatch(state2.op.top(), ":"))
+            if (!cpp || state2.op.empty() || !Token::simpleMatch(state2.op.top(), ":"))
                 throw InternalError(tok, "syntax error", InternalError::SYNTAX);
 
             semicolon1->astOperand2(state2.op.top());
diff --git a/test/testtokenize.cpp b/test/testtokenize.cpp
index 01be951e3..edd8a00a7 100644
--- a/test/testtokenize.cpp
+++ b/test/testtokenize.cpp
@@ -434,6 +434,7 @@ private:
         TEST_CASE(noCrash4);
         TEST_CASE(noCrash5); // #10603
         TEST_CASE(noCrash6); // #10212
+        TEST_CASE(noCrash7);
 
         // --check-config
         TEST_CASE(checkConfiguration);
@@ -7357,6 +7358,12 @@ private:
                                              "struct c<a<e, d...>, true> {};\n"));
     }
 
+    void noCrash7() {
+        ASSERT_THROW(tokenizeAndStringify("void g() {\n"// TODO: don't throw
+                                          "    for (using T = int; (T)false;) {}\n" // C++23 P2360R0: Extend init-statement to allow alias-declaration
+                                          "}\n"), InternalError);
+    }
+
     void checkConfig(const char code[]) {
         errout.str("");