From 458d53f5723314b946d0b401bf91e417131263e9 Mon Sep 17 00:00:00 2001
From: Edward Welbourne <edward.welbourne@qt.io>
Date: Fri, 10 Sep 2021 16:32:00 +0200
Subject: Move locale-switching code in tests to a shared header
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QLocale and QString tests had copies of a TransientLocale; we've
recently improved the QLocale one. Rather than duplicating those
rather complicated improvements, finally share a common version.

In the process, I noticed that setlocale() only returns the prior
value when passed nullptr as the new value; so rework the
implementation to get that right, so that it now correctly restores
the prior locale. That, in turn, means there's now a later call to
setlocale(), when we actually set the changed setting, which may
invalidate the earlier return; so copy it to a QByteArray before the
second call.

Included Ivan Solovev's improved version of how to reset the locale,
since TransientLocale needs it.

Pick-to: 6.2
Change-Id: I4cb1efbda42f0e2cdd934e04b3b3732ce0f45a06
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
---
 tests/shared/localechange.h | 111 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 111 insertions(+)
 create mode 100644 tests/shared/localechange.h

(limited to 'tests/shared')

diff --git a/tests/shared/localechange.h b/tests/shared/localechange.h
new file mode 100644
index 0000000000..135909eea5
--- /dev/null
+++ b/tests/shared/localechange.h
@@ -0,0 +1,111 @@
+/****************************************************************************
+**
+** Copyright (C) 2021 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL-EXCEPT$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QT_TESTS_SHARED_LOCALE_CHANGE_H
+#define QT_TESTS_SHARED_LOCALE_CHANGE_H
+#include <qglobal.h>
+#include <QtCore/QByteArray>
+#include <QtCore/QLocale>
+#include <private/qlocale_p.h>
+
+#include <locale.h>
+
+namespace QTestLocaleChange {
+
+    QLocale resetSystemLocale()
+    {
+#ifndef QT_NO_SYSTEMLOCALE
+        { // Transient instance marks system locale data as stale:
+            QSystemLocale dummy;
+        } // Now we can reinitialize:
+#endif
+        return QLocale::system();
+    }
+
+    class TransientLocale
+    {
+        const int m_category;
+        const QByteArray m_prior;
+        const bool m_didSet;
+#if !defined(QT_NO_SYSTEMLOCALE) && defined(Q_OS_UNIX) \
+    && (!defined(Q_OS_DARWIN) || defined(Q_OS_NACL))
+#define TRANSIENT_ENV
+        // Unix system locale consults environment variables, so we need to set
+        // the appropriate one, too.
+        const QByteArray m_envVar, m_envPrior;
+        const bool m_envSet;
+        static QByteArray categoryToEnv(int category)
+        {
+            switch (category) {
+#define CASE(cat) case cat: return #cat
+            CASE(LC_ALL); CASE(LC_NUMERIC); CASE(LC_TIME); CASE(LC_MONETARY);
+            CASE(LC_MESSAGES); CASE(LC_MEASUREMENT); CASE(LC_COLLATE);
+#undef CASE
+            // Nothing in our code pays attention to any other LC_*
+            default:
+                Q_UNREACHABLE();
+                qFatal("You need to add a case for this category");
+            }
+        }
+#endif // TRANSIENT_ENV
+    public:
+        TransientLocale(int category, const char *locale)
+            : m_category(category),
+              m_prior(setlocale(category, nullptr)),
+              // That return value may be stomped by this later call, so we copy
+              // it to a QByteArray for safe keeping.
+              m_didSet(setlocale(category, locale) != nullptr)
+#ifdef TRANSIENT_ENV
+            , m_envVar(categoryToEnv(category)),
+              m_envPrior(qgetenv(m_envVar.constData())),
+              m_envSet(qputenv(m_envVar.constData(), locale))
+#endif
+        {
+            resetSystemLocale();
+        }
+        ~TransientLocale()
+        {
+#ifdef TRANSIENT_ENV
+            if (m_envSet) {
+                if (m_envPrior.isEmpty())
+                    qunsetenv(m_envVar.constData());
+                else
+                    qputenv(m_envVar.constData(), m_envPrior);
+            }
+#endif
+            if (m_prior.size())
+                setlocale(m_category, m_prior.constData());
+            resetSystemLocale();
+        }
+#undef TRANSIENT_ENV
+
+        bool isValid() const { return m_didSet; }
+    };
+}
+
+#endif // QT_TESTS_SHARED_LOCALE_CHANGE_H
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