From a79a5e1d45e9b87faed302fcf0909228969e38ba Mon Sep 17 00:00:00 2001
From: Juho Teperi <juho.teperi@iki.fi>
Date: Sun, 19 Dec 2021 15:43:29 +0200
Subject: [PATCH] Test different ways to declare fn should be used as
 functional component

---
 src/reagent/impl/template.cljs    | 19 +++++++------
 test/reagenttest/testreagent.cljs | 44 ++++++++++++++++++++++++++++++-
 2 files changed, 54 insertions(+), 9 deletions(-)

diff --git a/src/reagent/impl/template.cljs b/src/reagent/impl/template.cljs
index 959f67e8..c1ec4c36 100644
--- a/src/reagent/impl/template.cljs
+++ b/src/reagent/impl/template.cljs
@@ -155,14 +155,6 @@
                  ;; https://www.w3.org/TR/custom-elements/#custom-elements-core-concepts
                  (not= -1 (.indexOf tag "-")))))
 
-(defn reag-element [tag v compiler]
-  (let [c (comp/as-class tag compiler)
-        jsprops #js {}]
-    (set! (.-argv jsprops) v)
-    (when-some [key (util/react-key-from-vec v)]
-      (set! (.-key jsprops) key))
-    (react/createElement c jsprops)))
-
 (defn function-element [tag v first-arg compiler]
   (let [jsprops #js {}]
     (set! (.-reagentRender jsprops) tag)
@@ -172,6 +164,17 @@
       (set! (.-key jsprops) key))
     (react/createElement (comp/functional-render-fn compiler tag) jsprops)))
 
+(defn reag-element [^clj tag v compiler]
+  (if (or (:functional (meta tag))
+          (.-functional tag))
+    (function-element tag v 1 compiler)
+    (let [c (comp/as-class tag compiler)
+          jsprops #js {}]
+      (set! (.-argv jsprops) v)
+      (when-some [key (util/react-key-from-vec v)]
+        (set! (.-key jsprops) key))
+      (react/createElement c jsprops))))
+
 (defn maybe-function-element
   "If given tag is a Class, use it as a class,
   else wrap in Reagent function wrapper."
diff --git a/test/reagenttest/testreagent.cljs b/test/reagenttest/testreagent.cljs
index 26cd3bcb..a685350e 100644
--- a/test/reagenttest/testreagent.cljs
+++ b/test/reagenttest/testreagent.cljs
@@ -1604,16 +1604,58 @@
             (r/flush)
             (is (= 3 @render))))))))
 
+(defn ^:functional f1
+  [x]
+  [:span "Hello " x])
+
+(defn f2
+  {:functional true}
+  [x]
+  [:span "Hello " x])
+
+(defn f3
+  [x]
+  [:span "Hello " x])
+(set! (.-functional ^clj f3) true)
+
+; (js/console.log f1 (pr-str (meta f1)) (pr-str (meta #'f1)))
+; (js/console.log f2 (pr-str (meta f2)) (pr-str (meta #'f2)))
+
 (deftest functional-component-poc-simple
   (when r/is-client
     (let [c (fn [x]
-              [:span "Hello " x])]
+              [:span "Hello " x])
+          f0 (with-meta c {:functional true})]
         (testing ":f>"
           (with-mounted-component [:f> c "foo"]
             (fn [c div]
               (is (nil? c) "Render returns nil for stateless components")
               (is (= "Hello foo" (.-innerText div))))))
 
+        (testing "with-meta"
+          (with-mounted-component [f0 "foo"]
+            (fn [c div]
+              (is (nil? c) "Render returns nil for stateless components")
+              (is (= "Hello foo" (.-innerText div))))))
+
+        (testing "defn symbol meta"
+          (with-mounted-component [#'f1 "foo"]
+            (fn [c div]
+              (is (nil? c) "Render returns nil for stateless components")
+              (is (= "Hello foo" (.-innerText div))))))
+
+        (testing "defn fn meta"
+          (with-mounted-component [#'f2 "foo"]
+            (fn [c div]
+              (is (nil? c) "Render returns nil for stateless components")
+              (is (= "Hello foo" (.-innerText div))))))
+
+        (testing "fn property"
+          (with-mounted-component [f3 "foo"]
+            (fn [c div]
+              (is (nil? c) "Render returns nil for stateless components")
+              (is (= "Hello foo" (.-innerText div))))))
+
         (testing "compiler options"
           (with-mounted-component [c "foo"]
             functional-compiler