commit f8ad329f7ee01993c388f78851fc4ac88f5093b4

Author: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>

Date:   Thu Nov 12 13:22:02 2020 +0100

    QCharRef: properly disable assignment from char

    Under QT_NO_CAST_FROM_ASCII the assignment would fall back

    to operator=(int) after a promotion. Add a deleted overload

    to block this. (QChar itself uses a private constructor

    for the same purpose, but I chose the C++11 solution).

    Nothing to do in Qt 6, QCharRef is gone.

    Change-Id: Iba50ad2b6ad95d7c3a5e4920ab03fae5d3db0319

    Fixes: QTBUG-88431

    Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

    Reviewed-by: Albert Astals Cid <aacid@kde.org>

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

diff --git b/src/corelib/text/qstring.h a/src/corelib/text/qstring.h

index fe97279aaf..5a4ac497e0 100644

--- b/src/corelib/text/qstring.h

+++ a/src/corelib/text/qstring.h

@@ -1231,10 +1231,6 @@ public:

     { return operator=(QChar::fromLatin1(c)); }

     inline QT_ASCII_CAST_WARN QCharRef &operator=(uchar c)

     { return operator=(QChar::fromLatin1(c)); }

-#else

-    // prevent char -> int promotion, bypassing QT_NO_CAST_FROM_ASCII

-    QCharRef &operator=(char c) = delete;

-    QCharRef &operator=(uchar c) = delete;

 #endif

     inline QCharRef &operator=(const QCharRef &c) { return operator=(QChar(c)); }

     inline QCharRef &operator=(ushort rc) { return operator=(QChar(rc)); }