fix(lsp): force lsp-zig-download-url-format to change

Can't change the variable after lsp-zig loads because its used when it's
loaded. Can't set it before lsp-zig loads because it's a
constant (resetting its value). Thank god it uses a (non-inlined)
function to build that URL, so we have an easy target to advise.

Fix: #7970
Amend: 93dfb0acfb
Amend: bc5a8ec3fa
Amend: 7bb5df4cd4

modules/tools/lsp/+lsp.el

@@ -43,9 +43,20 @@ Can be a list of backends; accepts any value `company-backends' accepts.")
   (when (modulep! :config default +bindings)
     (setq lsp-keymap-prefix nil))
 
-  ;; REVIEW: Remove when zigtools/zls#1879 is resolved.
   (unless (featurep :system 'windows)
-    (setq lsp-zig-download-url-format "https://github.com/zigtools/zls/releases/latest/download/zls-%s-%s.tar.xz"))
+    ;; HACK: Frustratingly enough, the value of `lsp-zig-download-url-format' is
+    ;;   used immediately while the lsp-zig package is loading, so changing it
+    ;;   *after* lsp-zig makes no difference. What's worse, the variable is a
+    ;;   constant, so we can't change it *before* the package is loaded either!
+    ;;   Thank god a (non-inlined) function is used to build the URL, so we have
+    ;;   something to advise.
+    ;; REVIEW: Remove when zigtools/zls#1879 is resolved.
+    (defadvice! +lsp--use-correct-zls-download-url-a (fn &rest _)
+      "See zigtools/zls#1879."
+      :around #'lsp-zig--zls-url
+      (let ((lsp-zig-download-url-format
+             "https://github.com/zigtools/zls/releases/latest/download/zls-%s-%s.tar.xz"))
+        (apply fn args))))
 
   :config
   (add-to-list 'doom-debug-variables 'lsp-log-io)