fix(core/dfn): prevent adding data-local-lt to data-lt (#5014)

Author: dontcallmedom

src/core/dfn.js

@@ -71,11 +71,12 @@ export function run() {
     computeType(dfn, linkingText);
     computeExport(dfn);
 
-    // Only add `lt`s that are different from the text content
-    if (titles.length === 1 && linkingText === norm(dfn.textContent)) {
-      continue;
+    // Only add `lt`s that are different from the text content and local-lts
+    const localLt = (dfn.dataset.localLt || "").split("|").map(norm);
+    const lt = titles.filter(t => !localLt.includes(t));
+    if (lt.length > 1 || linkingText !== norm(dfn.textContent)) {
+      dfn.dataset.lt = lt.join("|");
     }
-    dfn.dataset.lt = titles.join("|");
   }
 }
 

tests/spec/core/dfn-spec.js

@@ -221,6 +221,7 @@ describe("Core — Definitions", () => {
 
     const dfnOnlyLocalLt = doc.querySelector("#only-local-lt dfn");
     expect(dfnOnlyLocalLt.id).toBe("dfn-install");
+    expect(dfnOnlyLocalLt.dataset.lt).toBe(undefined);
     for (const el of [...doc.querySelectorAll("#only-local-lt a")]) {
       expect(el.hash).toBe("#dfn-install");
     }