tests: fix some -Wvolatile

C++20 deprecated compound volatile statements such as pre- and
post-increments, to stress that they're not atomic. So instead of

    volatile i;
    ~~~~;
    ++i;

you're now supposed to write

    volatile i;
    ~~~~;
    int j = i; // volatile load
    ++j;
    i = j; // volatile store

which matches more closely what hardware does.

Instead of fixing every use of volatile pre- or post-increment in this
fashion individually, and realising that probably a few more Qt
modules will have the same kind of code patterns in them, write
QtPrivate functions to do the job centrally.

Change-Id: I838097bd484ef2118c071726963f103c080d2ba5
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

2 files changed, 4 insertions, 1 deletions

diff --git a/tests/auto/corelib/tools/qsharedpointer/CMakeLists.txt b/tests/auto/corelib/tools/qsharedpointer/CMakeLists.txt
index f43b83b819..d29f203bf9 100644
--- a/tests/auto/corelib/tools/qsharedpointer/CMakeLists.txt
+++ b/tests/auto/corelib/tools/qsharedpointer/CMakeLists.txt
@@ -8,4 +8,6 @@ qt_internal_add_test(tst_qsharedpointer
         nontracked.cpp
         wrapper.cpp
         tst_qsharedpointer.cpp
+    PUBLIC_LIBRARIES
+        Qt::CorePrivate
 )
diff --git a/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp b/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
index e6e3329ed3..48464aff58 100644
--- a/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
+++ b/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
@@ -37,6 +37,7 @@
 #include <QtCore/QList>
 #include <QtCore/QMap>
 #include <QtCore/QThread>
+#include <QtCore/private/qvolatile_p.h>
 
 #include "forwarddeclared.h"
 #include "nontracked.h"
@@ -1944,7 +1945,7 @@ class ThreadData
     QAtomicInt * volatile ptr;
 public:
     ThreadData(QAtomicInt *p) : ptr(p) { }
-    ~ThreadData() { ++ptr; }
+    ~ThreadData() { QtPrivate::volatilePreIncrement(ptr); }
     void ref()
     {
         // if we're called after the destructor, we'll crash