LibTimeZone+Userland: Include Link entries when returning all time zones

We currently only return primary time zones, i.e. time zones that are
not a Link. LibJS will require knowledge of Link entries, and whether
each entry is or is not a Link.

Userland/Applications/ClockSettings/TimeZoneSettingsWidget.cpp

@@ -63,7 +63,17 @@ TimeZoneSettingsWidget::TimeZoneSettingsWidget()
 {
     load_from_gml(time_zone_settings_widget_gml).release_value_but_fixme_should_propagate_errors();
 
-    static auto time_zones = TimeZone::all_time_zones();
+    static auto time_zones = []() {
+        Vector<StringView> time_zones;
+
+        for (auto const& time_zone : TimeZone::all_time_zones()) {
+            if (time_zone.is_link == TimeZone::IsLink::No)
+                time_zones.append(time_zone.name);
+        }
+
+        return time_zones;
+    }();
+
     m_time_zone = TimeZone::system_time_zone();
 
     m_time_zone_combo_box = *find_descendant_of_type_named<GUI::ComboBox>("time_zone_input");

Userland/Libraries/LibJS/Runtime/Intl/Intl.cpp

@@ -87,10 +87,10 @@ static Vector<StringView> available_canonical_time_zones()
     Vector<StringView> result;
 
     // 3. For each element name of names, do
-    for (auto name : names) {
+    for (auto const& name : names) {
         // a. Assert: IsValidTimeZoneName( name ) is true.
         // b. Let canonical be ! CanonicalizeTimeZoneName( name ).
-        auto canonical = TimeZone::canonicalize_time_zone(name).value();
+        auto canonical = TimeZone::canonicalize_time_zone(name.name).value();
 
         // c. If result does not contain an element equal to canonical, then
         if (!result.contains_slow(canonical)) {

Userland/Libraries/LibTimeZone/TimeZone.cpp

@@ -143,10 +143,10 @@ ErrorOr<void> change_time_zone([[maybe_unused]] StringView time_zone)
 #endif
 }
 
-ReadonlySpan<StringView> __attribute__((weak)) all_time_zones()
+ReadonlySpan<TimeZoneIdentifier> __attribute__((weak)) all_time_zones()
 {
 #if !ENABLE_TIME_ZONE_DATA
-    static constexpr auto utc = Array { "UTC"sv };
+    static constexpr auto utc = Array { TimeZoneIdentifier { "UTC"sv, IsLink::No } };
     return utc;
 #else
     return {};

Userland/Libraries/LibTimeZone/TimeZone.h

@@ -19,6 +19,16 @@
 
 namespace TimeZone {
 
+enum class IsLink {
+    No,
+    Yes,
+};
+
+struct TimeZoneIdentifier {
+    StringView name;
+    IsLink is_link { IsLink::No };
+};
+
 enum class InDST {
     No,
     Yes,
@@ -52,7 +62,7 @@ struct Location {
 StringView system_time_zone();
 StringView current_time_zone();
 ErrorOr<void> change_time_zone(StringView time_zone);
-ReadonlySpan<StringView> all_time_zones();
+ReadonlySpan<TimeZoneIdentifier> all_time_zones();
 
 Optional<TimeZone> time_zone_from_string(StringView time_zone);
 StringView time_zone_to_string(TimeZone time_zone);

Userland/Utilities/timezone.cpp

@@ -27,7 +27,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     if (list_time_zones) {
         for (auto time_zone : TimeZone::all_time_zones())
-            outln("{}", time_zone);
+            outln("{}", time_zone.name);
         return 0;
     }