Long live qUtf16Printable()

QString::asprintf() has the ability to take a ushort* array as
obtained from QString::utf16() and insert that into the output
with an %ls conversion.

But no-one ever used this, because just passing QString::utf16()
to QString::asprintf() creates a warning about wchar_t* expected,
but ushort* provided.

The new qUtf16Printable() macro adds the necessary casts (via void*
to prevent any "type-punned pointer" warnings) to make
passing QString::utf16() to QString::asprintf() work silently.

This should greatly reduce the need to do a round-trip via utf-8
just to print the contents of a QString.

[ChangeLog][QtCore] Added qUtf16Printable().

Change-Id: I7ddd8d2b2a2191c9faa26aca95d49850d94b287c
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/corelib/global/qglobal.h b/src/corelib/global/qglobal.h
index 64d9f79faf..9b8029990c 100644
--- a/src/corelib/global/qglobal.h
+++ b/src/corelib/global/qglobal.h
@@ -687,6 +687,15 @@ Q_CORE_EXPORT bool qSharedBuild() Q_DECL_NOTHROW;
 #  define qUtf8Printable(string) QString(string).toUtf8().constData()
 #endif
 
+/*
+    Wrap QString::utf16() with enough casts to allow passing it
+    to QString::asprintf("%ls") without warnings.
+*/
+#ifndef qUtf16Printable
+#  define qUtf16Printable(string) \
+    static_cast<const wchar_t*>(static_cast<const void*>(QString(string).utf16()))
+#endif
+
 class QString;
 Q_CORE_EXPORT QString qt_error_string(int errorCode = -1);