Region & Language KCM: generate locales with glibc's localedef directly,
instead of appending to /etc/locale.gen and running the distribution
specific locale-gen wrapper, which T2 does not ship.

The helper runs "localedef -i <locale> -c -f UTF-8 <locale>.UTF-8" for
every selected locale, one after another. The KCM side no longer treats
a missing /etc/locale.gen as "nothing to do".

Signed-off-by: René Rebe <rene@exactco.de>

--- plasma-workspace-6.7.3/kcms/region_language/localegenhelper/localegenhelper.h.vanilla
+++ plasma-workspace-6.7.3/kcms/region_language/localegenhelper/localegenhelper.h
@@ -1,6 +1,7 @@
 /*
     localegenhelper.h
     SPDX-FileCopyrightText: 2021 Han Young <hanyoung@protonmail.com>
+    SPDX-FileCopyrightText: 2026 René Rebe <rene@exactco.de>
 
     SPDX-License-Identifier: GPL-2.0-or-later
 */
@@ -8,14 +9,11 @@
 #include <PolkitQt1/Authority>
 #include <QCoreApplication>
 #include <QDBusContext>
-#include <QFile>
 #include <QObject>
 #include <QProcess>
 #include <QRegularExpression>
 #include <QTimer>
 
-#include <set>
-
 using namespace std::chrono;
 class LocaleGenHelper : public QObject, protected QDBusContext
 {
@@ -31,16 +29,17 @@ private Q_SLOTS:
     void enableLocalesPrivate(PolkitQt1::Authority::Result result);
 
 private:
-    void handleLocaleGen(int statusCode, QProcess::ExitStatus status, QProcess *process);
-    bool editLocaleGen();
+    void handleLocaleDef(int statusCode, QProcess::ExitStatus status, QProcess *process);
+    bool generateLocales();
+    void generateNextLocale();
     void exitAfterTimeOut();
     bool shouldGenerate();
     void processLocales(const QStringList &locales);
 
     std::atomic<bool> m_isGenerating = false;
-    bool m_comment = false;
-    std::set<QString> m_alreadyEnabled;
     PolkitQt1::Authority *m_authority = nullptr;
     QStringList m_locales;
+    QStringList m_pendingLocales;
+    QString m_localeDefPath;
     QTimer m_timer;
 };
--- plasma-workspace-6.7.3/kcms/region_language/localegenhelper/localegenhelper.cpp.vanilla
+++ plasma-workspace-6.7.3/kcms/region_language/localegenhelper/localegenhelper.cpp
@@ -1,6 +1,7 @@
 /*
     localegenhelper.cpp
     SPDX-FileCopyrightText: 2021 Han Young <hanyoung@protonmail.com>
+    SPDX-FileCopyrightText: 2026 René Rebe <rene@exactco.de>
 
     SPDX-License-Identifier: GPL-2.0-or-later
 */
@@ -11,11 +12,26 @@
 
 #include <QDBusConnection>
 #include <QDebug>
+#include <QStandardPaths>
 
 #include <chrono>
+#include <utility>
 
 using namespace Qt::StringLiterals;
 
+// splits a locale name into its base and @modifier part, dropping the charset
+static std::pair<QString, QString> splitLocaleName(const QString &name)
+{
+    const qsizetype at = name.indexOf(u'@');
+    const QString modifier = at < 0 ? QString() : name.mid(at);
+    QString base = at < 0 ? name : name.left(at);
+    const qsizetype dot = base.indexOf(u'.');
+    if (dot >= 0) {
+        base.truncate(dot);
+    }
+    return {base, modifier};
+}
+
 LocaleGenHelper::LocaleGenHelper()
     : m_authority(PolkitQt1::Authority::instance())
 {
@@ -62,100 +78,83 @@ void LocaleGenHelper::enableLocalesPriva
 {
     qDebug() << result;
     if (result != PolkitQt1::Authority::Result::Yes) {
-        Q_EMIT error(i18n("Unauthorized to edit locale configuration file"));
+        Q_EMIT error(i18n("Unauthorized to generate locales"));
         exitAfterTimeOut();
         return;
     }
 
-    // if success, handleLocaleGen will call exit
-    if (editLocaleGen()) {
+    // handleLocaleDef schedules the exit once the last localedef run finished
+    if (!generateLocales()) {
         exitAfterTimeOut();
     }
 }
 
 bool LocaleGenHelper::shouldGenerate()
 {
-    QFile localegen(QStringLiteral("/etc/locale.gen"));
-    if (!localegen.open(QIODevice::ReadOnly)) {
-        return false;
-    }
-    m_alreadyEnabled.clear();
-    while (!localegen.atEnd()) {
-        QString locale = QString::fromLocal8Bit(localegen.readLine().simplified());
-        if (!m_comment && locale == u"# generated by KDE Plasma Region & Language KCM") {
-            m_comment = true;
-        }
-        if (locale.isEmpty() || locale.front() == u'#') {
-            continue;
-        }
-        const QList<QStringView> localeAndCharset = QStringView(locale).split(u' ');
-        if (localeAndCharset.size() != 2 || localeAndCharset.at(1) != u"UTF-8") {
-            continue;
-        } else {
-            QString localeNameWithoutCharset = localeAndCharset.front().toString().remove(".UTF-8"_L1);
-            m_alreadyEnabled.insert(localeNameWithoutCharset);
-        }
-    }
     for (const auto &locale : std::as_const(m_locales)) {
-        if (locale == QLatin1Char('C')) {
-            continue;
-        }
-        if (m_alreadyEnabled.count(locale) == 0) {
+        if (locale != QLatin1Char('C')) {
             return true;
         }
     }
     return false;
 }
 
-bool LocaleGenHelper::editLocaleGen()
+bool LocaleGenHelper::generateLocales()
 {
-    bool result = false;
-    QFile localegen(QStringLiteral("/etc/locale.gen"));
-    if (!localegen.open(QIODevice::Append)) {
-        Q_EMIT error(i18n("Can't open file `/etc/locale.gen`"));
-        return result;
+    m_localeDefPath = QStandardPaths::findExecutable(QStringLiteral("localedef"));
+    if (m_localeDefPath.isEmpty()) {
+        m_localeDefPath = QStandardPaths::findExecutable(QStringLiteral("localedef"),
+                                                        {
+                                                            QStringLiteral("/usr/bin"),
+                                                            QStringLiteral("/usr/sbin"),
+                                                            QStringLiteral("/sbin"),
+                                                        });
+    }
+    if (m_localeDefPath.isEmpty()) {
+        Q_EMIT error(i18n("Can't locate executable `localedef`"));
+        return false;
     }
+
+    m_pendingLocales.clear();
     for (const auto &locale : std::as_const(m_locales)) {
-        if (m_alreadyEnabled.count(locale) || locale == QLatin1Char('C')) {
-            continue;
+        if (locale != QLatin1Char('C')) {
+            m_pendingLocales.append(locale);
         }
-        // start at newline first time
-        if (!m_comment) {
-            localegen.write("\n# generated by KDE Plasma Region & Language KCM\n");
-            m_comment = true;
-        }
-        localegen.write(locale.toUtf8() + ".UTF-8 UTF-8\n"_ba);
     }
-
-    QString localeGenPath = QStandardPaths::findExecutable(QStringLiteral("locale-gen"));
-    if (localeGenPath.isEmpty()) {
-        localeGenPath = QStandardPaths::findExecutable(QStringLiteral("locale-gen"),
-                                                       {
-                                                           QStringLiteral("/usr/sbin"),
-                                                           QStringLiteral("/sbin"),
-                                                           QStringLiteral("/usr/local/sbin"),
-                                                       });
-    }
-    if (!localeGenPath.isEmpty()) {
-        auto *process = new QProcess(this);
-        process->setProgram(localeGenPath);
-        connect(process, &QProcess::finished, this, [this, process](int statusCode, QProcess::ExitStatus status) {
-            handleLocaleGen(statusCode, status, process);
-        });
-        process->start();
-        result = true;
-    } else {
-        Q_EMIT error(i18n("Can't locate executable `locale-gen`"));
+    if (m_pendingLocales.isEmpty()) {
+        Q_EMIT success();
+        return false;
     }
-    return result;
+
+    generateNextLocale();
+    return true;
 }
 
-void LocaleGenHelper::handleLocaleGen(int statusCode, QProcess::ExitStatus status, QProcess *process)
+void LocaleGenHelper::generateNextLocale()
 {
-    Q_UNUSED(status)
-    if (statusCode == 0) {
-        Q_EMIT success();
-    } else {
+    const QString locale = m_pendingLocales.takeFirst();
+    const auto [base, modifier] = splitLocaleName(locale);
+
+    // the source definition carries the modifier, the compiled name has it after the charset
+    auto *process = new QProcess(this);
+    process->setProgram(m_localeDefPath);
+    process->setArguments({QStringLiteral("-i"),
+                           base + modifier,
+                           QStringLiteral("-c"),
+                           QStringLiteral("-f"),
+                           QStringLiteral("UTF-8"),
+                           base + ".UTF-8"_L1 + modifier});
+    connect(process, &QProcess::finished, this, [this, process](int statusCode, QProcess::ExitStatus status) {
+        handleLocaleDef(statusCode, status, process);
+    });
+    process->start();
+}
+
+void LocaleGenHelper::handleLocaleDef(int statusCode, QProcess::ExitStatus status, QProcess *process)
+{
+    // localedef exits 1 if it only issued warnings, 4 if no output was written
+    const bool ok = status == QProcess::NormalExit && statusCode <= 1;
+    if (!ok) {
         QString all_error;
         if (!process) {
             all_error = i18n("Unknown");
@@ -164,8 +163,20 @@ void LocaleGenHelper::handleLocaleGen(in
             all_error.append(QLatin1Char('\n'));
             all_error.append(QString::fromLocal8Bit(process->readAllStandardError()));
         }
+        m_pendingLocales.clear();
         Q_EMIT error(all_error);
     }
+    if (process) {
+        process->deleteLater();
+    }
+
+    if (!m_pendingLocales.isEmpty()) {
+        generateNextLocale();
+        return;
+    }
+    if (ok) {
+        Q_EMIT success();
+    }
     exitAfterTimeOut();
 }
 
--- plasma-workspace-6.7.3/kcms/region_language/localegeneratorglibc.cpp.vanilla
+++ plasma-workspace-6.7.3/kcms/region_language/localegeneratorglibc.cpp
@@ -2,6 +2,7 @@
     localegeneratorglibc.cpp
     SPDX-FileCopyrightText: 2022 Han Young <hanyoung@protonmail.com>
     SPDX-FileCopyrightText: 2022 Harald Sitter <sitter@kde.org>
+    SPDX-FileCopyrightText: 2026 René Rebe <rene@exactco.de>
 
     SPDX-License-Identifier: GPL-2.0-or-later
 */
@@ -21,12 +22,6 @@ LocaleGeneratorGlibc::LocaleGeneratorGli
 void LocaleGeneratorGlibc::localesGenerate(const QStringList &list)
 {
     qCDebug(KCM_REGIONANDLANG) << "enable locales: " << list;
-    if (!QFile::exists(QStringLiteral("/etc/locale.gen"))) {
-        // When locale.gen is not present we assume that to mean that no generation is necessary, meaning we are done.
-        // e.g. fedora, centos and derivates
-        Q_EMIT needsFont();
-        return;
-    }
     qCDebug(KCM_REGIONANDLANG) << "send polkit request";
     auto reply = m_interface->enableLocales(list);
     if (reply.isError()) {