From 7f054782ad0dde832e22e5cc1fb1186c1340d020 Mon Sep 17 00:00:00 2001
From: Evan You <yyx990803@gmail.com>
Date: Sat, 2 Nov 2019 21:33:37 -0400
Subject: [PATCH] feat: warn ref usage on functional components

---
 packages/runtime-core/src/renderer.ts | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/packages/runtime-core/src/renderer.ts b/packages/runtime-core/src/renderer.ts
index 8f67ce6b..3416cccd 100644
--- a/packages/runtime-core/src/renderer.ts
+++ b/packages/runtime-core/src/renderer.ts
@@ -804,6 +804,14 @@ export function createRenderer<
       }
     }
     if (n2.ref !== null && parentComponent !== null) {
+      if (__DEV__ && !(n2.shapeFlag & ShapeFlags.STATEFUL_COMPONENT)) {
+        pushWarningContext(n2)
+        warn(
+          `Functional components do not support "ref" because they do not ` +
+            `have instances.`
+        )
+        popWarningContext()
+      }
       setRef(n2.ref, n1 && n1.ref, parentComponent, n2.component!.renderProxy)
     }
   }