CLJS-2134: Warn on variadic signatures in protocol method implementation as well

Author: swannodette

src/main/clojure/cljs/analyzer.cljc

@@ -138,6 +138,7 @@
    :protocol-duped-method true
    :protocol-multiple-impls true
    :protocol-with-variadic-method true
+   :protocol-impl-with-variadic-method true
    :protocol-impl-recur-with-target true
    :single-segment-namespace true
    :munged-namespace true
@@ -360,6 +361,11 @@
   (str "Protocol " (:protocol info) " declares method "
        (:name info) " with variadic signature (&)"))
 
+(defmethod error-message :protocol-impl-with-variadic-method
+  [warning-type info]
+  (str "Protocol " (:protocol info) " implements method "
+    (:name info) " with variadic signature (&)"))
+
 (defmethod error-message :protocol-impl-recur-with-target
   [warning-type info]
   (str "Ignoring target object \"" (pr-str (:form info)) "\" passed in recur to protocol method head"))

src/main/clojure/cljs/core.cljc

@@ -1498,6 +1498,8 @@
                      c   (count sig)]
             (core/when (contains? seen c)
               (ana/warning :protocol-duped-method env {:protocol p :fname fname}))
+            (core/when (some '#{&} sig)
+              (ana/warning :protocol-impl-with-variadic-method env {:protocol p :name fname}))
             (core/when (core/and (not= decmeths ::not-found) (not (some #{c} (map count decmeths))))
               (ana/warning :protocol-invalid-method env {:protocol p :fname fname :invalid-arity c}))
             (recur (next sigs) (conj seen c))))))))