Leave some Qt 6 remarks for QStringRef

QStringRef could have been trivial. The destructor is empty, the copy
constructor copies exactly the members and has an empty body and all the
members are POD. Both functions should be removed or defaulted in Qt 6.
When the destructor is defaulted, we can make the constructor constexpr.

We can't do that now because QStringRef is exported and some nasty
compilers (MSVC) like to export all functions, even inline ones, and
then call them without emitting a local copy.

Change-Id: Ie7509fd1a3f737a6c9156ea078d13bb347fc6be0
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/corelib/tools/qstring.h b/src/corelib/tools/qstring.h
index 1e45da060c..9cde603c0b 100644
--- a/src/corelib/tools/qstring.h
+++ b/src/corelib/tools/qstring.h
@@ -1173,13 +1173,17 @@ class Q_CORE_EXPORT QStringRef {
     int m_position;
     int m_size;
 public:
+    // ### Qt 6: make this constructor constexpr, after the destructor is made trivial
     inline QStringRef():m_string(0), m_position(0), m_size(0){}
     inline QStringRef(const QString *string, int position, int size);
     inline QStringRef(const QString *string);
+
+    // ### Qt 6: remove this copy constructor, the implicit one is fine
     inline QStringRef(const QStringRef &other)
         :m_string(other.m_string), m_position(other.m_position), m_size(other.m_size)
         {}
 
+    // ### Qt 6: remove this destructor, the implicit one is fine
     inline ~QStringRef(){}
     inline const QString *string() const { return m_string; }
     inline int position() const { return m_position; }