Merge remote-tracking branch 'origin/tqtc/lts-5.15.9' into tqtc/lts-5.15-opensourcev5.15.9-lts-lgpl

Change-Id: Iaff6b55275e50d19973e1020853d8622587069f9

1 files changed, 1 insertions, 1 deletions

diff --git a/src/corelib/text/qstring.cpp b/src/corelib/text/qstring.cpp
index 3e88ab4859..8deeae47bb 100644
--- a/src/corelib/text/qstring.cpp
+++ b/src/corelib/text/qstring.cpp
@@ -12312,7 +12312,7 @@ static qsizetype qLastIndexOf(Haystack haystack0, qsizetype from,
     const auto needle = needle0.data();
     const auto *end = haystack;
     haystack += from;
-    const std::size_t sl_minus_1 = sl - 1;
+    const std::size_t sl_minus_1 = sl ? sl - 1 : 0;
     const auto *n = needle + sl_minus_1;
     const auto *h = haystack + sl_minus_1;
     std::size_t hashNeedle = 0, hashHaystack = 0;