Add systemTimeZoneId() to the C++20 tzdb backend of QTimeZone

It's not strictly necessary, but it should be a little more efficient. Without it, QTZ::systemTimeZoneId() falls back to using the id() of a default-constructed backend, QChronoTZP(), which will get the same answer returned here, but we can avoid the need for that fall-back by doing the right lookup to begin with. Change-Id: I6fe5beba048b5e9817b6bfed6eba785b13c2c206 Reviewed-by: Thiago Macieira <[email protected]>
isolovev · Oct 21, 2024 · 92d24e5 · 92d24e5
1 parent 74c481b
commit 92d24e5
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diff --git a/src/corelib/time/qtimezoneprivate_chrono.cpp b/src/corelib/time/qtimezoneprivate_chrono.cpp
@@ -62,6 +62,15 @@ QChronoTimeZonePrivate::QChronoTimeZonePrivate(QByteArrayView id)
 QChronoTimeZonePrivate::~QChronoTimeZonePrivate()
         = default;
 
+QByteArray QChronoTimeZonePrivate::systemTimeZoneId() const
+{
+    if (const time_zone *zone = std::chrono::current_zone()) {
+        std::string_view name = zone->name();
+        return {name.begin(), qsizetype(name.size())};
+    }
+    return {};
+}
+
 QString QChronoTimeZonePrivate::abbreviation(qint64 atMSecsSinceEpoch) const
 {
     if (auto info = infoAtEpochMillis(m_timeZone, atMSecsSinceEpoch))

diff --git a/src/corelib/time/qtimezoneprivate_p.h b/src/corelib/time/qtimezoneprivate_p.h
@@ -241,6 +241,8 @@ class QChronoTimeZonePrivate final : public QTimeZonePrivate
     QChronoTimeZonePrivate(QByteArrayView id);
     ~QChronoTimeZonePrivate() override;
 
+    QByteArray systemTimeZoneId() const override;
+
     QString abbreviation(qint64 atMSecsSinceEpoch) const override;
     int offsetFromUtc(qint64 atMSecsSinceEpoch) const override;
     int standardTimeOffset(qint64 atMSecsSinceEpoch) const override;