QString::lastIndexOf: fix off-by-one for zero length matches

Otherwise, it would report that lastIndexOf of an empty pattern
in an empty string doesn't exist. Next commit adds extensive autotests;
for now, disable a broken autotest (which already features a comment
about why it's broken).

Change-Id: I9a0e5c0142007f81f5cf93e356c8bd82f00066f7
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit be83ff65c424cff1036e7da19d6175826d9f7ed9)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/src/corelib/text/qstring.cpp b/src/corelib/text/qstring.cpp
index f88aad1654..102658e7e9 100644
--- a/src/corelib/text/qstring.cpp
+++ b/src/corelib/text/qstring.cpp
@@ -4263,13 +4263,13 @@ qsizetype QString::lastIndexOf(const QRegularExpression &re, qsizetype from, QRe
         return -1;
     }
 
-    qsizetype endpos = (from < 0) ? (size() + from + 1) : (from + 1);
+    qsizetype endpos = (from < 0) ? (size() + from + 1) : (from);
     QRegularExpressionMatchIterator iterator = re.globalMatch(*this);
     qsizetype lastIndex = -1;
     while (iterator.hasNext()) {
         QRegularExpressionMatch match = iterator.next();
         qsizetype start = match.capturedStart();
-        if (start < endpos) {
+        if (start <= endpos) {
             lastIndex = start;
             if (rmatch)
                 *rmatch = std::move(match);