From c06555324e6f34e184d8893d86763bcab8151eed Mon Sep 17 00:00:00 2001
From: alex-stepchenkov-neyber <alex.stepchenkov@neyber.co.uk>
Date: Thu, 1 Mar 2018 13:51:02 +0200
Subject: [PATCH 1/3] Return only when the provided expression is a function
 but not when it is a statement or expression

---
 src/compiler/codegen/events.js             |  2 +-
 test/unit/modules/compiler/codegen.spec.js | 44 +++++++++++-----------
 2 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/src/compiler/codegen/events.js b/src/compiler/codegen/events.js
index 722e32a4d60..9ebd8f531c5 100644
--- a/src/compiler/codegen/events.js
+++ b/src/compiler/codegen/events.js
@@ -119,7 +119,7 @@ function genHandler (
       code += genModifierCode
     }
     const handlerCode = isMethodPath
-      ? handler.value + '($event)'
+      ? `return ${handler.value}($event)`
       : isFunctionExpression
         ? `(${handler.value})($event)`
         : handler.value
diff --git a/test/unit/modules/compiler/codegen.spec.js b/test/unit/modules/compiler/codegen.spec.js
index 745ef33c228..b5e5a267570 100644
--- a/test/unit/modules/compiler/codegen.spec.js
+++ b/test/unit/modules/compiler/codegen.spec.js
@@ -265,42 +265,42 @@ describe('codegen', () => {
   it('generate events with keycode', () => {
     assertCodegen(
       '<input @input.enter="onInput">',
-      `with(this){return _c('input',{on:{"input":function($event){if(!('button' in $event)&&_k($event.keyCode,"enter",13,$event.key))return null;onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"input":function($event){if(!('button' in $event)&&_k($event.keyCode,"enter",13,$event.key))return null;return onInput($event)}}})}`
     )
     // multiple keycodes (delete)
     assertCodegen(
       '<input @input.delete="onInput">',
-      `with(this){return _c('input',{on:{"input":function($event){if(!('button' in $event)&&_k($event.keyCode,"delete",[8,46],$event.key))return null;onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"input":function($event){if(!('button' in $event)&&_k($event.keyCode,"delete",[8,46],$event.key))return null;return onInput($event)}}})}`
     )
     // multiple keycodes (chained)
     assertCodegen(
       '<input @keydown.enter.delete="onInput">',
-      `with(this){return _c('input',{on:{"keydown":function($event){if(!('button' in $event)&&_k($event.keyCode,"enter",13,$event.key)&&_k($event.keyCode,"delete",[8,46],$event.key))return null;onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"keydown":function($event){if(!('button' in $event)&&_k($event.keyCode,"enter",13,$event.key)&&_k($event.keyCode,"delete",[8,46],$event.key))return null;return onInput($event)}}})}`
     )
     // number keycode
     assertCodegen(
       '<input @input.13="onInput">',
-      `with(this){return _c('input',{on:{"input":function($event){if(!('button' in $event)&&$event.keyCode!==13)return null;onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"input":function($event){if(!('button' in $event)&&$event.keyCode!==13)return null;return onInput($event)}}})}`
     )
     // custom keycode
     assertCodegen(
       '<input @input.custom="onInput">',
-      `with(this){return _c('input',{on:{"input":function($event){if(!('button' in $event)&&_k($event.keyCode,"custom",undefined,$event.key))return null;onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"input":function($event){if(!('button' in $event)&&_k($event.keyCode,"custom",undefined,$event.key))return null;return onInput($event)}}})}`
     )
   })
 
   it('generate events with generic modifiers', () => {
     assertCodegen(
       '<input @input.stop="onInput">',
-      `with(this){return _c('input',{on:{"input":function($event){$event.stopPropagation();onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"input":function($event){$event.stopPropagation();return onInput($event)}}})}`
     )
     assertCodegen(
       '<input @input.prevent="onInput">',
-      `with(this){return _c('input',{on:{"input":function($event){$event.preventDefault();onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"input":function($event){$event.preventDefault();return onInput($event)}}})}`
     )
     assertCodegen(
       '<input @input.self="onInput">',
-      `with(this){return _c('input',{on:{"input":function($event){if($event.target !== $event.currentTarget)return null;onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"input":function($event){if($event.target !== $event.currentTarget)return null;return onInput($event)}}})}`
     )
   })
 
@@ -308,74 +308,74 @@ describe('codegen', () => {
   it('generate events with generic modifiers and keycode correct order', () => {
     assertCodegen(
       '<input @keydown.enter.prevent="onInput">',
-      `with(this){return _c('input',{on:{"keydown":function($event){if(!('button' in $event)&&_k($event.keyCode,"enter",13,$event.key))return null;$event.preventDefault();onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"keydown":function($event){if(!('button' in $event)&&_k($event.keyCode,"enter",13,$event.key))return null;$event.preventDefault();return onInput($event)}}})}`
     )
 
     assertCodegen(
       '<input @keydown.enter.stop="onInput">',
-      `with(this){return _c('input',{on:{"keydown":function($event){if(!('button' in $event)&&_k($event.keyCode,"enter",13,$event.key))return null;$event.stopPropagation();onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"keydown":function($event){if(!('button' in $event)&&_k($event.keyCode,"enter",13,$event.key))return null;$event.stopPropagation();return onInput($event)}}})}`
     )
   })
 
   it('generate events with mouse event modifiers', () => {
     assertCodegen(
       '<input @click.ctrl="onClick">',
-      `with(this){return _c('input',{on:{"click":function($event){if(!$event.ctrlKey)return null;onClick($event)}}})}`
+      `with(this){return _c('input',{on:{"click":function($event){if(!$event.ctrlKey)return null;return onClick($event)}}})}`
     )
     assertCodegen(
       '<input @click.shift="onClick">',
-      `with(this){return _c('input',{on:{"click":function($event){if(!$event.shiftKey)return null;onClick($event)}}})}`
+      `with(this){return _c('input',{on:{"click":function($event){if(!$event.shiftKey)return null;return onClick($event)}}})}`
     )
     assertCodegen(
       '<input @click.alt="onClick">',
-      `with(this){return _c('input',{on:{"click":function($event){if(!$event.altKey)return null;onClick($event)}}})}`
+      `with(this){return _c('input',{on:{"click":function($event){if(!$event.altKey)return null;return onClick($event)}}})}`
     )
     assertCodegen(
       '<input @click.meta="onClick">',
-      `with(this){return _c('input',{on:{"click":function($event){if(!$event.metaKey)return null;onClick($event)}}})}`
+      `with(this){return _c('input',{on:{"click":function($event){if(!$event.metaKey)return null;return onClick($event)}}})}`
     )
     assertCodegen(
       '<input @click.exact="onClick">',
-      `with(this){return _c('input',{on:{"click":function($event){if($event.ctrlKey||$event.shiftKey||$event.altKey||$event.metaKey)return null;onClick($event)}}})}`
+      `with(this){return _c('input',{on:{"click":function($event){if($event.ctrlKey||$event.shiftKey||$event.altKey||$event.metaKey)return null;return onClick($event)}}})}`
     )
     assertCodegen(
       '<input @click.ctrl.exact="onClick">',
-      `with(this){return _c('input',{on:{"click":function($event){if(!$event.ctrlKey)return null;if($event.shiftKey||$event.altKey||$event.metaKey)return null;onClick($event)}}})}`
+      `with(this){return _c('input',{on:{"click":function($event){if(!$event.ctrlKey)return null;if($event.shiftKey||$event.altKey||$event.metaKey)return null;return onClick($event)}}})}`
     )
   })
 
   it('generate events with multiple modifiers', () => {
     assertCodegen(
       '<input @input.stop.prevent.self="onInput">',
-      `with(this){return _c('input',{on:{"input":function($event){$event.stopPropagation();$event.preventDefault();if($event.target !== $event.currentTarget)return null;onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"input":function($event){$event.stopPropagation();$event.preventDefault();if($event.target !== $event.currentTarget)return null;return onInput($event)}}})}`
     )
   })
 
   it('generate events with capture modifier', () => {
     assertCodegen(
       '<input @input.capture="onInput">',
-      `with(this){return _c('input',{on:{"!input":function($event){onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"!input":function($event){return onInput($event)}}})}`
     )
   })
 
   it('generate events with once modifier', () => {
     assertCodegen(
       '<input @input.once="onInput">',
-      `with(this){return _c('input',{on:{"~input":function($event){onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"~input":function($event){return onInput($event)}}})}`
     )
   })
 
   it('generate events with capture and once modifier', () => {
     assertCodegen(
       '<input @input.capture.once="onInput">',
-      `with(this){return _c('input',{on:{"~!input":function($event){onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"~!input":function($event){return onInput($event)}}})}`
     )
   })
 
   it('generate events with once and capture modifier', () => {
     assertCodegen(
       '<input @input.once.capture="onInput">',
-      `with(this){return _c('input',{on:{"~!input":function($event){onInput($event)}}})}`
+      `with(this){return _c('input',{on:{"~!input":function($event){return onInput($event)}}})}`
     )
   })
 
@@ -445,7 +445,7 @@ describe('codegen', () => {
   it('generate multiple event handlers', () => {
     assertCodegen(
       '<input @input="current++" @input.stop="onInput">',
-      `with(this){return _c('input',{on:{"input":[function($event){current++},function($event){$event.stopPropagation();onInput($event)}]}})}`
+      `with(this){return _c('input',{on:{"input":[function($event){current++},function($event){$event.stopPropagation();return onInput($event)}]}})}`
     )
   })
 

From d4569337cf992d562c4b5c1bbbefe13031efb6da Mon Sep 17 00:00:00 2001
From: alex-stepchenkov-neyber <alex.stepchenkov@neyber.co.uk>
Date: Thu, 1 Mar 2018 15:50:07 +0200
Subject: [PATCH 2/3] Return value for function expression

---
 src/compiler/codegen/events.js             | 2 +-
 test/unit/modules/compiler/codegen.spec.js | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/compiler/codegen/events.js b/src/compiler/codegen/events.js
index 9ebd8f531c5..1cbff814d1e 100644
--- a/src/compiler/codegen/events.js
+++ b/src/compiler/codegen/events.js
@@ -121,7 +121,7 @@ function genHandler (
     const handlerCode = isMethodPath
       ? `return ${handler.value}($event)`
       : isFunctionExpression
-        ? `(${handler.value})($event)`
+        ? `return (${handler.value})($event)`
         : handler.value
     /* istanbul ignore if */
     if (__WEEX__ && handler.params) {
diff --git a/test/unit/modules/compiler/codegen.spec.js b/test/unit/modules/compiler/codegen.spec.js
index b5e5a267570..c0b7e78f620 100644
--- a/test/unit/modules/compiler/codegen.spec.js
+++ b/test/unit/modules/compiler/codegen.spec.js
@@ -420,7 +420,7 @@ describe('codegen', () => {
     // with modifiers
     assertCodegen(
       `<input @keyup.enter="e=>current++">`,
-      `with(this){return _c('input',{on:{"keyup":function($event){if(!('button' in $event)&&_k($event.keyCode,"enter",13,$event.key))return null;(e=>current++)($event)}}})}`
+      `with(this){return _c('input',{on:{"keyup":function($event){if(!('button' in $event)&&_k($event.keyCode,"enter",13,$event.key))return null;return (e=>current++)($event)}}})}`
     )
   })
 

From 9e9f6c53694910664a2519749708803474bea768 Mon Sep 17 00:00:00 2001
From: alex-stepchenkov-neyber <alex.stepchenkov@neyber.co.uk>
Date: Sat, 3 Mar 2018 04:30:55 +0200
Subject: [PATCH 3/3] Add more tests for #7704

---
 test/unit/modules/compiler/codegen.spec.js    | 45 +++++++++++++++++++
 .../modules/vdom/patch/edge-cases.spec.js     | 37 +++++++++++++++
 2 files changed, 82 insertions(+)

diff --git a/test/unit/modules/compiler/codegen.spec.js b/test/unit/modules/compiler/codegen.spec.js
index c0b7e78f620..992a53ccca8 100644
--- a/test/unit/modules/compiler/codegen.spec.js
+++ b/test/unit/modules/compiler/codegen.spec.js
@@ -262,6 +262,51 @@ describe('codegen', () => {
     )
   })
 
+  it('generate events with method call', () => {
+    assertCodegen(
+      '<input @input="onInput($event);">',
+      `with(this){return _c('input',{on:{"input":function($event){onInput($event);}}})}`
+    )
+    // empty arguments
+    assertCodegen(
+      '<input @input="onInput();">',
+      `with(this){return _c('input',{on:{"input":function($event){onInput();}}})}`
+    )
+    // without semicolon
+    assertCodegen(
+      '<input @input="onInput($event)">',
+      `with(this){return _c('input',{on:{"input":function($event){onInput($event)}}})}`
+    )
+    // multiple args
+    assertCodegen(
+      '<input @input="onInput($event, \'abc\', 5);">',
+      `with(this){return _c('input',{on:{"input":function($event){onInput($event, 'abc', 5);}}})}`
+    )
+    // expression in args
+    assertCodegen(
+      '<input @input="onInput($event, 2+2);">',
+      `with(this){return _c('input',{on:{"input":function($event){onInput($event, 2+2);}}})}`
+    )
+    // tricky symbols in args
+    assertCodegen(
+      '<input @input="onInput(\');[\'());\');">',
+      `with(this){return _c('input',{on:{"input":function($event){onInput(');[\'());');}}})}`
+    )
+  })
+
+  it('generate events with multiple statements', () => {
+    // normal function
+    assertCodegen(
+      '<input @input="onInput1();onInput2()">',
+      `with(this){return _c('input',{on:{"input":function($event){onInput1();onInput2()}}})}`
+    )
+    // function with multiple args
+    assertCodegen(
+      '<input @input="onInput1($event, \'text\');onInput2(\'text2\', $event)">',
+      `with(this){return _c('input',{on:{"input":function($event){onInput1($event, 'text');onInput2('text2', $event)}}})}`
+    )
+  })
+
   it('generate events with keycode', () => {
     assertCodegen(
       '<input @input.enter="onInput">',
diff --git a/test/unit/modules/vdom/patch/edge-cases.spec.js b/test/unit/modules/vdom/patch/edge-cases.spec.js
index df60d0132ee..3d0a8b83628 100644
--- a/test/unit/modules/vdom/patch/edge-cases.spec.js
+++ b/test/unit/modules/vdom/patch/edge-cases.spec.js
@@ -25,6 +25,43 @@ describe('vdom patch: edge cases', () => {
     }).then(done)
   })
 
+  // exposed by #7705
+  // methods and function expressions with modifiers should return result instead of undefined
+  // skipped odd children[1,3, ...] because they are rendered as text nodes with undefined value
+  it('should return listener\'s result for method name and function expression with and w/o modifiers', done => {
+    const dummyEvt = { preventDefault: () => {} }
+    new Vue({
+      template: `
+        <div v-test>
+          <div @click="addFive"></div>
+          <div @click.prevent="addFive"></div>
+          <div @click="addFive($event, 5)"></div>
+          <div @click.prevent="addFive($event, 5)"></div>
+        </div>
+      `,
+      methods: {
+        addFive ($event, toAdd = 0) {
+          return toAdd + 5
+        }
+      },
+      directives: {
+        test: {
+          bind (el, binding, vnode) {
+            waitForUpdate(() => {
+              expect(vnode.children[0].data.on.click()).toBe(5)
+            }).then(() => {
+              expect(vnode.children[2].data.on.click(dummyEvt)).toBe(5)
+            }).then(() => {
+              expect(vnode.children[4].data.on.click()).not.toBeDefined()
+            }).then(() => {
+              expect(vnode.children[6].data.on.click(dummyEvt)).not.toBeDefined()
+            }).then(done)
+          }
+        }
+      }
+    }).$mount()
+  })
+
   // #3533
   // a static node is reused in createElm, which changes its elm reference
   // and is inserted into a different parent.