QString: fix an aliasing issue in remove(QString)

Even in Qt 5, remove() can be passed an alias to *this. In Qt 6, with
the advent of substring sharing, this will become even more
pronounced. Use the same fix as was already used in QString::insert().

Change-Id: I1a0d3d99fd7dff6e727661646d2cbfdc94df2682
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
(cherry picked from commit b655734965155146290f3f3a9205243af11e42fb)
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 9 insertions, 1 deletions

diff --git a/src/corelib/text/qstring.cpp b/src/corelib/text/qstring.cpp
index 6075285c71..7534551cd6 100644
--- a/src/corelib/text/qstring.cpp
+++ b/src/corelib/text/qstring.cpp
@@ -2898,7 +2898,15 @@ static void removeStringImpl(QString &s, const T &needle, Qt::CaseSensitivity cs
 */
 QString &QString::remove(const QString &str, Qt::CaseSensitivity cs)
 {
-    removeStringImpl(*this, str, cs);
+    const auto s = reinterpret_cast<const ushort *>(str.data());
+    const std::less<const ushort *> less = {};
+    if (!less(s, d->data()) && less(s, d->data() + d->alloc)) {
+        // Part of me - take a copy
+        const QVarLengthArray<ushort> copy(s, s + str.size());
+        removeStringImpl(*this, QStringView{copy.data(), copy.size()}, cs);
+    } else {
+        removeStringImpl(*this, qToStringViewIgnoringNull(str), cs);
+    }
     return *this;
 }