Preserve :tag metadata in copy-var

copy-var, copy-var*, and var-meta now propagate :tag metadata from
the original JVM var to the SCI var.

Author: borkdude

CHANGELOG.md

@@ -18,6 +18,7 @@ SCI is used in [babashka](https://github.com/babashka/babashka),
 - Fix `ns-map` not reflecting vars that shadow referred vars (e.g. `(defn inc ...)`)
 - `deftype` now macroexpands to `deftype*`, matching JVM Clojure, enabling code walkers like riddley
 - `case` now macroexpands to JVM-compatible `case*` format, enabling tools like riddley and cloverage to work with SCI
+- Preserve `:tag` metadata in `copy-var`
 - Fix `.method` on class objects (e.g. `(.getDeclaredField String "value")`) routing to static instead of instance method path
 - `macroexpand-1` of `(.method ClassName)` now wraps class targets in `identity`, matching Clojure behavior
 - `macroexpand-1` now accepts an optional env map as first argument, like `cljs.analyzer/macroexpand-1`

src/sci/core.cljc

@@ -75,10 +75,12 @@
             val# (deref var#)
             m# (-> var# meta)
             name# (or ~nm (:name m#))
-            new-m# {:doc (:doc m#)
-                    :name name#
-                    :arglists (:arglists m#)
-                    :ns ns#}]
+            tag# (:tag m#)
+            new-m# (cond-> {:doc (:doc m#)
+                            :name name#
+                            :arglists (:arglists m#)
+                            :ns ns#}
+                     tag# (assoc :tag tag#))]
         (cond (:dynamic m#)
               (new-dynamic-var name# val# new-m#)
               (or (:macro m#) (:sci/macro m#))
@@ -94,12 +96,14 @@
         arglists (:arglists m)
         dynamic (:dynamic m)
         macro (:macro m)
-        new-m (cond-> {:ns sci-ns
+        tag (:tag m)
+    new-m (cond-> {:ns sci-ns
                        :name nm}
                 macro (assoc :macro true)
                 doc (assoc :doc doc)
                 arglists (assoc :arglists arglists)
-                dynamic (assoc :dynamic dynamic))]
+                dynamic (assoc :dynamic dynamic)
+                tag (assoc :tag tag))]
     (new-var nm @clojure-var new-m)))
 
 (macros/deftime

src/sci/impl/copy_vars.cljc

@@ -55,11 +55,13 @@
                                                     :cljs (atom nil))])]
                     (macros/? :clj #?(:clj  (let [m (meta the-var)
                                                   dyn (:dynamic m)
-                                                  arglists (:arglists m)]
+                                                  arglists (:arglists m)
+                                                  tag (:tag m)]
                                               (cond-> (if elide-vars {} {:doc (:doc m)})
                                                 dyn (assoc :dynamic dyn)
                                                 (if elide-vars false arglists)
                                                 (assoc :arglists (list 'quote (:arglists m)))
+                                                tag (assoc :tag tag)
                                                 fast-path (assoc :sci.impl/fast-path (list 'quote sym))))
                                       :cljs nil)
                               :cljs (let [r (cljs-resolve &env fqsym)