From 7583485671835ecc3329519622948c1ce566f8fe Mon Sep 17 00:00:00 2001
From: TATSUNO Yasuhiro <tatsuno_yasuhiro@kurusugawa.jp>
Date: Sun, 14 Oct 2018 03:09:22 +0900
Subject: [PATCH] :bug: bug(index): Add warning for circular reference in
 linked message (#438) by @exoego

* Add warning for circular reference in linked message.

* Allow non-ascii chars including numbers.

* Circular reference warnings should tell us chain of reference.
---
 src/index.js               | 24 ++++++++++++++++++------
 test/unit/fixture/index.js |  4 ++++
 test/unit/issues.test.js   | 18 ++++++++++++++++++
 3 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/src/index.js b/src/index.js
index 2e27202ac..dcebb5ddc 100644
--- a/src/index.js
+++ b/src/index.js
@@ -199,7 +199,8 @@ export default class VueI18n {
     key: Path,
     host: any,
     interpolateMode: string,
-    values: any
+    values: any,
+    visitedLinkStack: Array<string>
   ): any {
     if (!message) { return null }
 
@@ -234,7 +235,7 @@ export default class VueI18n {
 
     // Check for the existance of links within the translated string
     if (ret.indexOf('@:') >= 0) {
-      ret = this._link(locale, message, ret, host, interpolateMode, values)
+      ret = this._link(locale, message, ret, host, interpolateMode, values, visitedLinkStack)
     }
 
     return this._render(ret, interpolateMode, values)
@@ -246,7 +247,8 @@ export default class VueI18n {
     str: string,
     host: any,
     interpolateMode: string,
-    values: any
+    values: any,
+    visitedLinkStack: Array<string>
   ): any {
     let ret: string = str
 
@@ -263,11 +265,19 @@ export default class VueI18n {
       const link: string = matches[idx]
       // Remove the leading @: and the brackets
       const linkPlaceholder: string = link.substr(2).replace(bracketsMatcher, '')
+
+      if (visitedLinkStack.includes(linkPlaceholder)) {
+        warn(`Circular reference found. "${link}" is already visited in the chain of ${visitedLinkStack.reverse().join(' <- ')}`)
+        return ret
+      }
+      visitedLinkStack.push(linkPlaceholder)
+
       // Translate the link
       let translated: any = this._interpolate(
         locale, message, linkPlaceholder, host,
         interpolateMode === 'raw' ? 'string' : interpolateMode,
-        interpolateMode === 'raw' ? undefined : values
+        interpolateMode === 'raw' ? undefined : values,
+        visitedLinkStack
       )
 
       if (this._isFallbackRoot(translated)) {
@@ -287,6 +297,8 @@ export default class VueI18n {
         Array.isArray(values) ? values : [values]
       )
 
+      visitedLinkStack.pop()
+
       // Replace the link with the translated
       ret = !translated ? ret : ret.replace(link, translated)
     }
@@ -311,10 +323,10 @@ export default class VueI18n {
     args: any
   ): any {
     let res: any =
-      this._interpolate(locale, messages[locale], key, host, interpolateMode, args)
+      this._interpolate(locale, messages[locale], key, host, interpolateMode, args, [key])
     if (!isNull(res)) { return res }
 
-    res = this._interpolate(fallback, messages[fallback], key, host, interpolateMode, args)
+    res = this._interpolate(fallback, messages[fallback], key, host, interpolateMode, args, [key])
     if (!isNull(res)) {
       if (process.env.NODE_ENV !== 'production' && !this._silentTranslationWarn) {
         warn(`Fall back to translate the keypath '${key}' with '${fallback}' locale.`)
diff --git a/test/unit/fixture/index.js b/test/unit/fixture/index.js
index b456f394b..d8cfc995a 100644
--- a/test/unit/fixture/index.js
+++ b/test/unit/fixture/index.js
@@ -17,6 +17,10 @@ export default {
       linkHyphen: '@:hyphen-hello',
       linkUnderscore: '@:underscore_hello',
       linkList: '@:message.hello: {0} {1}',
+      circular1: 'Foo @:message.circular2',
+      circular2: 'Bar @:message.circular3',
+      circular3: 'Buz @:message.circular1',
+      linkTwice: '@:message.hello: @:message.hello',
       'hyphen-locale': 'hello hyphen',
       '1234': 'Number-based keys are found',
       '1mixedKey': 'Mixed keys are not found.'
diff --git a/test/unit/issues.test.js b/test/unit/issues.test.js
index 5719e296e..aa1b8f3af 100644
--- a/test/unit/issues.test.js
+++ b/test/unit/issues.test.js
@@ -300,6 +300,24 @@ describe('issues', () => {
     })
   })
 
+  describe('#247', () => {
+    it('should be warned if circular reference in linked locale message', () => {
+      const spy = sinon.spy(console, 'warn')
+      assert.strictEqual(vm.$i18n.t('message.circular1'), 'Foo Bar Buz @:message.circular1')
+      assert(spy.notCalled === false)
+      assert(spy.callCount === 1)
+      spy.restore()
+    })
+
+    it('should not be warned if same non-circular link used repeatedly', () => {
+      const spy = sinon.spy(console, 'warn')
+      assert.strictEqual(vm.$i18n.t('message.linkTwice'), 'the world: the world')
+      assert(spy.notCalled === true)
+      assert(spy.callCount === 0)
+      spy.restore()
+    })
+  })
+
   describe('#377', () => {
     it('should be destroyed', done => {
       const el = document.createElement('div')