From 8bf4d5c78ff95c943c2772f9eeddb72d8266dd12 Mon Sep 17 00:00:00 2001
From: Yusuke Wada <yusuke@kamawada.com>
Date: Sun, 5 Jan 2025 18:00:47 +0900
Subject: [PATCH] fix(types): correct
 `app.on(method,path[],middleware,handler)` type

---
 src/types.test.ts | 8 ++++++++
 src/types.ts      | 4 ++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/types.test.ts b/src/types.test.ts
index 9a4720029..d1ec00107 100644
--- a/src/types.test.ts
+++ b/src/types.test.ts
@@ -277,6 +277,14 @@ describe('OnHandlerInterface', () => {
     }
     type verify = Expect<Equal<Expected, Actual>>
   })
+
+  test('app.on(method, path[], middleware, handler) should not throw a type error', () => {
+    const middleware: MiddlewareHandler<{ Variables: { foo: string } }> = async () => {}
+    app.on('GET', ['/a', '/b'], middleware, (c) => {
+      expectTypeOf(c.var.foo).toEqualTypeOf<string>()
+      return c.json({})
+    })
+  })
 })
 
 describe('TypedResponse', () => {
diff --git a/src/types.ts b/src/types.ts
index f58f162bd..bfa96a260 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -1745,10 +1745,10 @@ export interface OnHandlerInterface<
   ): HonoBase<E, S & ToSchema<string, MergePath<BasePath, P>, I, MergeTypedResponse<R>>, BasePath>
 
   // app.on(method | method[], path[], ...handlers[])
-  <I extends Input = BlankInput, R extends HandlerResponse<any> = any>(
+  <I extends Input = BlankInput, R extends HandlerResponse<any> = any, E2 extends Env = E>(
     methods: string | string[],
     paths: string[],
-    ...handlers: H<E, any, I, R>[]
+    ...handlers: H<E2, any, I, R>[]
   ): HonoBase<E, S & ToSchema<string, string, I, MergeTypedResponse<R>>, BasePath>
 }