Allow reusing of another functions `:doc` and `:arglists` about clojure-lsp

[yuhan0]

Well, not in the specific example given.. but I can imagine a situation where it could arise:

(defn- frob-impl ;; maybe a protocol method which can't take 0 args
  [{:keys [beep boop]}]
  ,,,)

(defn frob
  "public API with extra convenience arity"
  {:arglists (->> (:arglists (meta #'frob-impl))
                  (cons []))}
  ([] (frob default-opts))
  ([opts] (frob-impl opts)))

Of course it could be rewritten as (frob-impl default-opts), but figuring this out from the error stacktraces is not quite straightforward.

Either way if the syntax itself turns out to be officially unsupported or discouraged, it's probably not a good idea to build a feature around it? (I don't think it was definitively settled in the ask.clojure thread)

[yuhan0]

Note that function-a as defined will fail to compile when its body contains a call to itself:
https://ask.clojure.org/index.php/13834/compiler-exception-dynamically-arglists-metadata-recursive

The interpretation given by @puredanger in the linked thread was that :arglists in the attr-map should be restricted to literal quoted lists, so expressions to be evaluated like (:arglists (meta #'function-b)) should be at least discouraged (if not considered illegal).

[yuhan0]

To avoid this construction, one has to use alter-meta! on the var after its creation, which I imagine is trickier to statically analyze:

(defn function-a [args] 
  (function-b args)

(alter-meta! #'function-a 
             assoc  
             :arglists (:arglists (meta #'function-b)))
;; or
(alter-meta! #'function-a 
             merge 
             (select-keys (meta #'function-b)
                          [:arglists :doc]))

[didibus]

It should also include :macro meta for when you want to do this for a macro.

[didibus]

@yuhan0 I'm not sure if it matters here though, since you have one var copying another, it would never call itself no?