DEV: Add backward compatibility for tag object arrays

What is the problem?

Discourse core PR #36678 changes `renderTag` to pass tag objects
instead of strings to custom tag renderers. This breaks the
`iconTagRenderer` function which expects the `tag` parameter to be
a string and calls `escapeExpression(tag)` directly.

What is the solution?

Extract the tag name at the start of `iconTagRenderer` using
`typeof tag === "string" ? tag : tag.name` before processing.
Also rename the local `tagName` variable to `htmlTagName` to avoid
confusion with the extracted tag name. This ensures backward
compatibility with both the old string format and the new object format.

Author: tgxworld

javascripts/discourse/initializers/tag-icons.js

@@ -11,13 +11,16 @@ function iconTagRenderer(tag, params) {
   let tagIconList = settings.tag_icon_list.split("|");
 
   params = params || {};
-  const visibleName = escapeExpression(tag);
+  // TODO(https://github.com/discourse/discourse/pull/36678): The string check can be
+  // removed using .discourse-compatibility once the PR is merged.
+  const tagStr = typeof tag === "string" ? tag : tag.name;
+  const visibleName = escapeExpression(tagStr);
   tag = visibleName.toLowerCase();
 
   const classes = ["discourse-tag"];
-  const tagName = params.tagName || "a";
+  const htmlTagName = params.tagName || "a";
   let path;
-  if (tagName === "a" && !params.noHref) {
+  if (htmlTagName === "a" && !params.noHref) {
     if ((params.isPrivateMessage || params.pmOnly) && currentUser) {
       const username = params.tagsForUser
         ? params.tagsForUser
@@ -64,7 +67,7 @@ function iconTagRenderer(tag, params) {
 
   let val =
     "<" +
-    tagName +
+    htmlTagName +
     href +
     " data-tag-name=" +
     tag +
@@ -75,7 +78,7 @@ function iconTagRenderer(tag, params) {
     tagIconHTML + // inject tag Icon in html
     (params.displayName ? escape(params.displayName) : visibleName) +
     "</" +
-    tagName +
+    htmlTagName +
     ">";
 
   if (params.count) {

spec/system/tag_icons_spec.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+RSpec.describe "Tag icons", type: :system do
+  fab!(:tag) { Fabricate(:tag, name: "support") }
+  fab!(:topic) { Fabricate(:topic, tags: [tag]) }
+  fab!(:post) { Fabricate(:post, topic:) }
+  fab!(:user)
+
+  let(:topic_page) { PageObjects::Pages::Topic.new }
+  let!(:theme) { upload_theme_component }
+
+  before do
+    SiteSetting.tagging_enabled = true
+    theme.update_setting(:tag_icon_list, "support,question-circle,#ff0000")
+    theme.save!
+    sign_in(user)
+  end
+
+  it "displays tag with icon on topic page" do
+    topic_page.visit_topic(topic)
+    expect(page).to have_css(".discourse-tag[data-tag-name='support']")
+    expect(page).to have_css(".tag-icon[style*='color: #ff0000'] .d-icon-question-circle")
+  end
+
+  it "displays tag without icon when not configured" do
+    theme.update_setting(:tag_icon_list, "")
+    theme.save!
+
+    topic_page.visit_topic(topic)
+    expect(page).to have_css(".discourse-tag[data-tag-name='support']")
+    expect(page).to have_no_css(".tag-icon")
+  end
+end