[3.0] Stop drawing an empty tab menu with an unresolved label

[albertlast]

Description

Admin and moderation pages whose menu has no title of its own drew a mobile tab menu containing nothing, labelled with the literal text {label} Menu. Straight off Admin → Scheduled Tasks:

<a class="mobile_generic_menu_1_tabs">
	<span class="menu_icon"></span>
	<span class="text_menu">{label} Menu</span>
</a>
…
		<ul class="dropmenu dropdown_menu_1_tabs">
		</ul>

Two lists with the same name

The block is guarded on Utils::$context['tabs'] but draws $tab_context['tabs']:

if (!empty(Utils::$context['tabs'])) {
	…
	foreach ($tab_context['tabs'] as $sa => $tab) {

They are not the same list. Utils::$context['tabs'] is set as a side effect of drawing the menu itself, from whichever area is selected:

// template_generic_menu_dropdown_above()
if (!empty($area['selected']) && empty(Utils::$context['tabs'])) {
	Utils::$context['tabs'] = $area['subsections'] ?? [];
}

$tab_context['tabs'] is only assembled from it inside the if (!empty($tab_context['title'])) branch further up. So on a page that has subsections but no tab title, the first is full and the second was never built — the guard passes, the loop finds nothing.

And why the label stayed raw

$tab_context['title'] was never set either, so the call passes ['label' => null]. Localization\MessageFormatter::formatMessage() filters its arguments before handing them over:

->format(array_filter($args, 'is_scalar'))

is_scalar(null) is false, so the argument is dropped, and ICU leaves an unmatched placeholder in the output rather than substituting an empty string. Reproduced directly — ['label' => null] through intl gives " Menu", but with the argument filtered out it gives "{label} Menu".

The guard now names the list that actually gets drawn, and the label falls back to '' so the same thing cannot happen if a menu ever gets tabs without a title.

Checked

Four pages on the running forum. {label} no longer appears anywhere, Scheduled Tasks draws no #adm_submenus at all, and the pages that do have tabs are untouched:

<span class="text_menu">Reported Members Menu</span>
<span class="text_menu">Manage Members Menu</span>
<span class="text_menu">Features and Options Menu</span>

Found by sweeping every rendered page of a stock forum for unsubstituted {placeholders}. This is one of the three the sweep turned up.

GenericMenu.template.php is also touched by #9392, which makes this element a nav landmark; the two do not overlap.

Issues References (Fixes|Related|Closes)

Related to #7933

[albertlast]

Pushed a second commit.

Sweeping the admin area with the first commit applied turned up an Undefined array key "label" on ?action=admin;area=current_theme, which the change had exposed rather than caused. Themes::execute() sets four tabs on tab_data, each carrying only a description; the labels are meant to be filled in by the loop above, which walks Utils::$context[tabs]. current_theme is its own admin area with no subsections, so that array is empty, the loop never runs, and the four tabs stay unlabelled. Under the old guard the block was skipped for the same reason, so nothing was drawn and nothing complained.

An unlabelled tab cannot be drawn, so it should not count towards there being anything to draw either. Filtering first, then guarding on the result, handles both: pages with real tabs are unaffected, current_theme draws nothing at all. The disabled check folds into the same filter, and template_generic_menu() already skips unlabelled areas the same way a few lines above.

Verified on ?action=admin;area=theme;sa=list (all four tabs still render: Manage and Install, Theme Settings, Member Options, Modify Themes) and on ?action=admin;area=current_theme (no tab menu, and the error log stays clean).