QCborMap: remove the optimization not to detach from non-const find()

All our tests were find() == end() or !=, which depends on the
evaluation order of the arguments to operator==(). If end() is called
first, then the detach happens before find() and all is well. But if
find() is called first, it may return end() before end() detaches.

[ChangeLog][QCborMap] Fixed a bug that could cause the iterator returned
from a failing key search with find() not to match end(). Now, every
call to find() will detach in shared QCborMaps; to avoid this, use
constFind() and constEnd().

Fixes: QTBUG-84583
Pick-to: 5.15 5.12
Change-Id: I552d244076a447ab92d7fffd161793496a8d03a8
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

1 files changed, 4 insertions, 8 deletions

diff --git a/src/corelib/serialization/qcbormap.cpp b/src/corelib/serialization/qcbormap.cpp
index f3218c680d..9179ed81b6 100644
--- a/src/corelib/serialization/qcbormap.cpp
+++ b/src/corelib/serialization/qcbormap.cpp
@@ -834,9 +834,8 @@ QCborValueRef QCborMap::operator[](const QCborValue &key)
  */
 QCborMap::iterator QCborMap::find(qint64 key)
 {
+    detach();
     auto it = constFind(key);
-    if (it != constEnd())
-        detach();
     return { d.data(), it.item.i };
 }
 
@@ -860,9 +859,8 @@ QCborMap::iterator QCborMap::find(qint64 key)
  */
 QCborMap::iterator QCborMap::find(QLatin1String key)
 {
+    detach();
     auto it = constFind(key);
-    if (it != constEnd())
-        detach();
     return { d.data(), it.item.i };
 }
 
@@ -886,9 +884,8 @@ QCborMap::iterator QCborMap::find(QLatin1String key)
  */
 QCborMap::iterator QCborMap::find(const QString & key)
 {
+    detach();
     auto it = constFind(key);
-    if (it != constEnd())
-        detach();
     return { d.data(), it.item.i };
 }
 
@@ -912,9 +909,8 @@ QCborMap::iterator QCborMap::find(const QString & key)
  */
 QCborMap::iterator QCborMap::find(const QCborValue &key)
 {
+    detach();
     auto it = constFind(key);
-    if (it != constEnd())
-        detach();
     return { d.data(), it.item.i };
 }