CPlusPlus: Fix finding end of raw string literal

The employed algorithm lacked proper backtracking, potentially causing us
to miss the delimiter altogether.

Change-Id: I7993c3c27d034925bd884e192779c85c54be9ec4
Reviewed-by: hjk <hjk@qt.io>

1 files changed, 9 insertions, 9 deletions

diff --git a/src/libs/3rdparty/cplusplus/Lexer.cpp b/src/libs/3rdparty/cplusplus/Lexer.cpp
index deafe432b6..62a95f455a 100644
--- a/src/libs/3rdparty/cplusplus/Lexer.cpp
+++ b/src/libs/3rdparty/cplusplus/Lexer.cpp
@@ -838,16 +838,16 @@ void Lexer::scanRawStringLiteral(Token *tok, unsigned char hint)
 
 bool Lexer::scanUntilRawStringLiteralEndPrecise()
 {
-    int matchLen = 0;
+    QByteArray slidingWindow;
+    slidingWindow.reserve(_expectedRawStringSuffix.size());
     while (_yychar) {
-        if (_yychar == _expectedRawStringSuffix.at(matchLen)) {
-            if (++matchLen == _expectedRawStringSuffix.length()) {
-                _expectedRawStringSuffix.clear();
-                yyinp();
-                return true;
-            }
-        } else {
-            matchLen = 0;
+        slidingWindow.append(_yychar);
+        if (slidingWindow.size() > _expectedRawStringSuffix.size())
+            slidingWindow.removeFirst();
+        if (slidingWindow == _expectedRawStringSuffix) {
+            _expectedRawStringSuffix.clear();
+            yyinp();
+            return true;
         }
         yyinp();
     }