QCollator: don't pipe bcp47Name() through QString

Give QCollator access to QLocalePrivate::bcp47Name(), to avoid
both the latin-1 -> UTF-16 conversion in QLocale::bcp47Name(),
as well all as

- the replace('-', '_').toLatin1() call in ICU
- the toLocal8Bit() call in macOS
- the toUtf8() call in Windows

implementations of QCollatorPrivate::init().

This is safe, since, according to https://tools.ietf.org/html/bcp47,
a BCP47 name only contains US-ASCII (ALPHA used, which is defined by
https://tools.ietf.org/html/rfc5234 to be [a-zA-Z] only).

Change-Id: Id56befb1b5a7983494d848cdabf7ebeda377cf9f
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

src/corelib/tools/qcollator_icu.cpp

@@ -39,6 +39,7 @@
 ****************************************************************************/
 
 #include "qcollator_p.h"
+#include "qlocale_p.h"
 #include "qstringlist.h"
 #include "qstring.h"
 
@@ -56,7 +57,7 @@ void QCollatorPrivate::init()
     cleanup();
 
     UErrorCode status = U_ZERO_ERROR;
-    QByteArray name = locale.bcp47Name().replace(QLatin1Char('-'), QLatin1Char('_')).toLatin1();
+    QByteArray name = QLocalePrivate::get(locale)->bcp47Name('_');
     collator = ucol_open(name.constData(), &status);
     if (U_FAILURE(status)) {
         qWarning("Could not create collator: %d", status);

src/corelib/tools/qcollator_macx.cpp

@@ -38,9 +38,12 @@
 ****************************************************************************/
 
 #include "qcollator_p.h"
+#include "qlocale_p.h"
 #include "qstringlist.h"
 #include "qstring.h"
+
 #include <QtCore/private/qcore_mac_p.h>
+
 #include <CoreFoundation/CoreFoundation.h>
 #include <CoreFoundation/CFLocale.h>
 
@@ -53,7 +56,7 @@ void QCollatorPrivate::init()
 {
     cleanup();
     LocaleRef localeRef;
-    int rc = LocaleRefFromLocaleString(locale.bcp47Name().toLocal8Bit(), &localeRef);
+    int rc = LocaleRefFromLocaleString(QLocalePrivate::get(locale)->bcp47Name().constData(), &localeRef);
     if (rc != 0)
         qWarning("couldn't initialize the locale");
 

src/corelib/tools/qcollator_win.cpp

@@ -38,6 +38,7 @@
 ****************************************************************************/
 
 #include "qcollator_p.h"
+#include "qlocale_p.h"
 #include "qstringlist.h"
 #include "qstring.h"
 
@@ -61,7 +62,7 @@ void QCollatorPrivate::init()
     collator = 0;
 
 #ifndef USE_COMPARESTRINGEX
-    localeID = qt_inIsoNametoLCID(locale.bcp47Name().toUtf8().constData());
+    localeID = qt_inIsoNametoLCID(QLocalePrivate::get(locale)->bcp47Name().constData());
 #else
     localeName = locale.bcp47Name();
 #endif

src/corelib/tools/qlocale_p.h

@@ -332,6 +332,9 @@ public:
         return retval;
     }
 
+    static QLocalePrivate *get(QLocale &l) { return l.d; }
+    static const    QLocalePrivate *get(const QLocale &l) { return l.d; }
+
     QChar decimal() const { return QChar(m_data->m_decimal); }
     QChar group() const { return QChar(m_data->m_group); }
     QChar list() const { return QChar(m_data->m_list); }