From 9883f888501d50239272635398ca4d6dd0087354 Mon Sep 17 00:00:00 2001
From: Thiago Macieira <thiago.macieira@intel.com>
Date: Wed, 7 Aug 2024 15:28:51 -0700
Subject: [PATCH] QDebug: cast the QFlags value to the right-sized unsigned
 type (1/2)

This change fixes three problems in the non-Q_ENUM overload. First, the
printing of the sign bit for a signed flag. This is correct, but
unexpected:
  QFlags(0x1|0x2|-0x80000000)
By using unsigned types, we'll print instead:
  QFlags(0x1|0x2|0x80000000)

Second, shifting into the sign bit is UB, so we remove the problem by
not having a sign bit at all.

Third, this provides an out-of-line non-template overload of the
implementation for unsigned QFlags, thereby avoiding an unnecessary
instantiation of the template function qt_QMetaEnum_flagDebugOperator()
in user code.

Change-Id: I8a96935cf6c742259c9dfffd17e992caa315e1d3
Reviewed-by: Ahmad Samir <a.samirh78@gmail.com>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
(cherry picked from commit 91a27c1a516068b69ab62778a07c566ad22f3576)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 src/corelib/compat/removed_api.cpp          | 7 +++++++
 src/corelib/io/qdebug.cpp                   | 6 +++---
 src/corelib/io/qdebug.h                     | 7 +++++--
 tests/auto/corelib/io/qdebug/tst_qdebug.cpp | 7 ++++---
 4 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/src/corelib/compat/removed_api.cpp b/src/corelib/compat/removed_api.cpp
index 0963602ca5..44e6250813 100644
--- a/src/corelib/compat/removed_api.cpp
+++ b/src/corelib/compat/removed_api.cpp
@@ -984,6 +984,13 @@ QDataStream &QDataStream::operator<<(bool i)
     return (*this << qint8(i));
 }
 
+#include "qdebug.h"
+
+Q_CORE_EXPORT void qt_QMetaEnum_flagDebugOperator(QDebug &debug, size_t sizeofT, int value)
+{
+    qt_QMetaEnum_flagDebugOperator(debug, sizeofT, uint(value));
+}
+
 #include "qdir.h" // inlined API
 
 bool QDir::operator==(const QDir &dir) const
diff --git a/src/corelib/io/qdebug.cpp b/src/corelib/io/qdebug.cpp
index e9b58855f5..93a90953a9 100644
--- a/src/corelib/io/qdebug.cpp
+++ b/src/corelib/io/qdebug.cpp
@@ -1251,13 +1251,13 @@ QDebugStateSaver::~QDebugStateSaver()
     \internal
 
     Specialization of the primary template in qdebug.h to out-of-line
-    the common case of QFlags<T>::Int being int.
+    the common case of QFlags<T>::Int being 32-bit.
 
     Just call the generic version so the two don't get out of sync.
 */
-void qt_QMetaEnum_flagDebugOperator(QDebug &debug, size_t sizeofT, int value)
+void qt_QMetaEnum_flagDebugOperator(QDebug &debug, size_t sizeofT, uint value)
 {
-    qt_QMetaEnum_flagDebugOperator<int>(debug, sizeofT, value);
+    qt_QMetaEnum_flagDebugOperator<uint>(debug, sizeofT, value);
 }
 
 #ifndef QT_NO_QOBJECT
diff --git a/src/corelib/io/qdebug.h b/src/corelib/io/qdebug.h
index a2c270f5cd..ea0bb86938 100644
--- a/src/corelib/io/qdebug.h
+++ b/src/corelib/io/qdebug.h
@@ -488,11 +488,13 @@ inline QDebug operator<<(QDebug debug, const QTaggedPointer<T, Tag> &ptr)
     return debug;
 }
 
-Q_CORE_EXPORT void qt_QMetaEnum_flagDebugOperator(QDebug &debug, size_t sizeofT, int value);
+Q_CORE_EXPORT void qt_QMetaEnum_flagDebugOperator(QDebug &debug, size_t sizeofT, uint value);
 
 template <typename Int>
 void qt_QMetaEnum_flagDebugOperator(QDebug &debug, size_t sizeofT, Int value)
 {
+    static_assert(std::is_unsigned_v<Int>,
+            "Cast value to an unsigned type before calling this function");
     const QDebugStateSaver saver(debug);
     debug.resetFormat();
     debug.nospace() << "QFlags(" << Qt::hex << Qt::showbase;
@@ -556,7 +558,8 @@ template <class T>
 inline QDebug qt_QMetaEnum_flagDebugOperator_helper(QDebug debug, const QFlags<T> &flags)
 #endif
 {
-    qt_QMetaEnum_flagDebugOperator(debug, sizeof(T), typename QFlags<T>::Int(flags));
+    using UInt = typename QIntegerForSizeof<T>::Unsigned;
+    qt_QMetaEnum_flagDebugOperator(debug, sizeof(T), UInt(flags.toInt()));
     return debug;
 }
 
diff --git a/tests/auto/corelib/io/qdebug/tst_qdebug.cpp b/tests/auto/corelib/io/qdebug/tst_qdebug.cpp
index 7ee2ff42cc..877924e6e4 100644
--- a/tests/auto/corelib/io/qdebug/tst_qdebug.cpp
+++ b/tests/auto/corelib/io/qdebug/tst_qdebug.cpp
@@ -1082,7 +1082,8 @@ void tst_QDebug::qDebugQByteArrayView() const
 
 enum TestEnum {
     Flag1 = 0x1,
-    Flag2 = 0x10
+    Flag2 = 0x10,
+    SignFlag = INT_MIN,
 };
 
 Q_DECLARE_FLAGS(TestFlags, TestEnum)
@@ -1091,7 +1092,7 @@ void tst_QDebug::qDebugQFlags() const
 {
     QString file, function;
     int line = 0;
-    QFlags<TestEnum> flags(Flag1 | Flag2);
+    QFlags<TestEnum> flags(Flag1 | Flag2 | SignFlag);
 
     MessageHandlerSetter mhs(myMessageHandler);
     { qDebug() << flags; }
@@ -1099,7 +1100,7 @@ void tst_QDebug::qDebugQFlags() const
     file = __FILE__; line = __LINE__ - 2; function = Q_FUNC_INFO;
 #endif
     QCOMPARE(s_msgType, QtDebugMsg);
-    QCOMPARE(s_msg, QString::fromLatin1("QFlags(0x1|0x10)"));
+    QCOMPARE(s_msg, QString::fromLatin1("QFlags(0x1|0x10|0x80000000)"));
     QCOMPARE(QString::fromLatin1(s_file), file);
     QCOMPARE(s_line, line);
     QCOMPARE(QString::fromLatin1(s_function), function);