From 66d16b51f0822ae9945e0baa393543a7163614b5 Mon Sep 17 00:00:00 2001
From: Simon Martin <simartin@users.noreply.github.com>
Date: Sat, 10 Feb 2018 14:39:57 +0100
Subject: [PATCH] Ticket #8352: Properly detect AST cycles. (#1060)

---
 lib/token.cpp        | 8 ++++----
 test/testgarbage.cpp | 6 ++++++
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/lib/token.cpp b/lib/token.cpp
index 71e320908..24a80d055 100644
--- a/lib/token.cpp
+++ b/lib/token.cpp
@@ -1078,13 +1078,13 @@ std::string Token::stringifyList(bool varid) const
 
 void Token::astOperand1(Token *tok)
 {
-    const Token* const root = tok;
     if (_astOperand1)
         _astOperand1->_astParent = nullptr;
     // goto parent operator
     if (tok) {
+        std::set<Token*> visitedParents;
         while (tok->_astParent) {
-            if (tok->_astParent == this || tok->_astParent == root) // #6838/#6726 avoid hang on garbage code
+            if (!visitedParents.insert(tok->_astParent).second) // #6838/#6726/#8352 avoid hang on garbage code
                 throw InternalError(this, "Internal error. Token::astOperand1() cyclic dependency.");
             tok = tok->_astParent;
         }
@@ -1095,14 +1095,14 @@ void Token::astOperand1(Token *tok)
 
 void Token::astOperand2(Token *tok)
 {
-    const Token* const root = tok;
     if (_astOperand2)
         _astOperand2->_astParent = nullptr;
     // goto parent operator
     if (tok) {
+        std::set<Token*> visitedParents;
         while (tok->_astParent) {
             //std::cout << tok << " -> " << tok->_astParent ;
-            if (tok->_astParent == this || tok->_astParent == root) // #6838/#6726 avoid hang on garbage code
+            if (!visitedParents.insert(tok->_astParent).second) // #6838/#6726 avoid hang on garbage code
                 throw InternalError(this, "Internal error. Token::astOperand2() cyclic dependency.");
             tok = tok->_astParent;
         }
diff --git a/test/testgarbage.cpp b/test/testgarbage.cpp
index ed809834c..ba993ed4a 100644
--- a/test/testgarbage.cpp
+++ b/test/testgarbage.cpp
@@ -1253,6 +1253,12 @@ private:
                                "b[i + 3] = a[i] * {}"), InternalError); // Don't hang (#5787)
 
         checkCode("START_SECTION([EXTRA](bool isValid(const String &filename)))"); // Don't crash (#5991)
+
+        // #8352
+        ASSERT_THROW(checkCode("else return % name5 name2 - =name1 return enum | { - name3 1 enum != >= 1 >= ++ { { || "
+                               "{ return return { | { - name3 1 enum != >= 1 >= ++ { name6 | ; ++}}}}}}}"), InternalError);
+        ASSERT_THROW(checkCode("else return % name5 name2 - =name1 return enum | { - name3 1 enum != >= 1 >= ++ { { || "
+                               "{ return return { | { - name3 1 enum != >= 1 >= ++ { { || ; ++}}}}}}}}"), InternalError);
     }
 
     void templateSimplifierCrashes() {