QMultiHash::find - prevent detaching shared null

Do not detach when find(key, value) is called on an empty QMultiHash.

As a drive-by: fix return value for QMultiHash::remove() in case of
empty QMultiHash.

Task-number: QTBUG-91736
Change-Id: I1e32f359e7ee9ce8403dae79d02e0b88a20ec4a5
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
(cherry picked from commit 82499f81478032911d8f788aa28e8d780b31c973)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/src/corelib/tools/qhash.h b/src/corelib/tools/qhash.h
index 1a793e6163..bfa2da6dbd 100644
--- a/src/corelib/tools/qhash.h
+++ b/src/corelib/tools/qhash.h
@@ -1782,7 +1782,7 @@ public:
     qsizetype remove(const Key &key, const T &value)
     {
         if (isEmpty()) // prevents detaching shared null
-            return false;
+            return 0;
         detach();
 
         auto it = d->find(key);
@@ -1844,6 +1844,8 @@ public:
 
     iterator find(const Key &key, const T &value)
     {
+        if (isEmpty())
+            return end();
         detach();
         auto it = constFind(key, value);
         return iterator(it.i, it.e);