From aa498e9138f6499bd76ce172e69662ef1ceea6fe Mon Sep 17 00:00:00 2001
From: HcySunYang <HcySunYang@outlook.com>
Date: Tue, 9 Mar 2021 12:36:08 +0800
Subject: [PATCH 1/5] feat(compiler): take the comments option to fully control
 whether to keep comment nodes

---
 packages/compiler-core/__tests__/parse.spec.ts | 12 +++---------
 packages/compiler-core/src/parse.ts            | 14 +++++++-------
 2 files changed, 10 insertions(+), 16 deletions(-)

diff --git a/packages/compiler-core/__tests__/parse.spec.ts b/packages/compiler-core/__tests__/parse.spec.ts
index a93b5e0404c..63f97ca9f4c 100644
--- a/packages/compiler-core/__tests__/parse.spec.ts
+++ b/packages/compiler-core/__tests__/parse.spec.ts
@@ -377,23 +377,17 @@ describe('compiler: parse', () => {
     })
 
     test('comments option', () => {
-      __DEV__ = false
-      const astDefaultComment = baseParse('<!--abc-->')
-      const astNoComment = baseParse('<!--abc-->', { comments: false })
       const astWithComments = baseParse('<!--abc-->', { comments: true })
-      __DEV__ = true
+      const astNoComment = baseParse('<!--abc-->', { comments: false })
 
-      expect(astDefaultComment.children).toHaveLength(0)
-      expect(astNoComment.children).toHaveLength(0)
       expect(astWithComments.children).toHaveLength(1)
+      expect(astNoComment.children).toHaveLength(0)
     })
 
     // #2217
     test('comments in the <pre> tag should be removed in production mode', () => {
-      __DEV__ = false
       const rawText = `<p/><!-- foo --><p/>`
-      const ast = baseParse(`<pre>${rawText}</pre>`)
-      __DEV__ = true
+      const ast = baseParse(`<pre>${rawText}</pre>`, { comments: false })
 
       expect((ast.children[0] as ElementNode).children).toMatchObject([
         {
diff --git a/packages/compiler-core/src/parse.ts b/packages/compiler-core/src/parse.ts
index d57ca77a03e..d73da01d27a 100644
--- a/packages/compiler-core/src/parse.ts
+++ b/packages/compiler-core/src/parse.ts
@@ -59,7 +59,8 @@ export const defaultParserOptions: MergedParserOptions = {
   decodeEntities: (rawText: string): string =>
     rawText.replace(decodeRE, (_, p1) => decodeMap[p1]),
   onError: defaultOnError,
-  comments: false
+  // only keep comment nodes in DEV by default
+  comments: __DEV__
 }
 
 export const enum TextModes {
@@ -101,7 +102,10 @@ function createParserContext(
   const options = extend({}, defaultParserOptions)
   for (const key in rawOptions) {
     // @ts-ignore
-    options[key] = rawOptions[key] || defaultParserOptions[key]
+    options[key] =
+      rawOptions[key] === undefined
+        ? defaultParserOptions[key]
+        : rawOptions[key]
   }
   return {
     options,
@@ -238,11 +242,7 @@ function parseChildren(
         }
       }
       // also remove comment nodes in prod by default
-      if (
-        !__DEV__ &&
-        node.type === NodeTypes.COMMENT &&
-        !context.options.comments
-      ) {
+      if (node.type === NodeTypes.COMMENT && !context.options.comments) {
         removedWhitespace = true
         nodes[i] = null as any
       }

From 71c878fea42f83011883ad10bf2a1252e15faa18 Mon Sep 17 00:00:00 2001
From: HcySunYang <HcySunYang@outlook.com>
Date: Tue, 9 Mar 2021 12:40:56 +0800
Subject: [PATCH 2/5] chore: fit comments

---
 packages/compiler-core/src/parse.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/compiler-core/src/parse.ts b/packages/compiler-core/src/parse.ts
index d73da01d27a..4fcfb961171 100644
--- a/packages/compiler-core/src/parse.ts
+++ b/packages/compiler-core/src/parse.ts
@@ -241,7 +241,7 @@ function parseChildren(
           node.content = node.content.replace(/[\t\r\n\f ]+/g, ' ')
         }
       }
-      // also remove comment nodes in prod by default
+      // comment nodes handling
       if (node.type === NodeTypes.COMMENT && !context.options.comments) {
         removedWhitespace = true
         nodes[i] = null as any

From 8c801f1623eb8b549a1f50229ce945d882e85893 Mon Sep 17 00:00:00 2001
From: HcySunYang <HcySunYang@outlook.com>
Date: Tue, 9 Mar 2021 17:05:53 +0800
Subject: [PATCH 3/5] fix: types

---
 packages/compiler-core/src/parse.ts | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/packages/compiler-core/src/parse.ts b/packages/compiler-core/src/parse.ts
index 4fcfb961171..a76a0cd4c88 100644
--- a/packages/compiler-core/src/parse.ts
+++ b/packages/compiler-core/src/parse.ts
@@ -100,7 +100,8 @@ function createParserContext(
   rawOptions: ParserOptions
 ): ParserContext {
   const options = extend({}, defaultParserOptions)
-  for (const key in rawOptions) {
+  let key: keyof ParserOptions
+  for (key in rawOptions) {
     // @ts-ignore
     options[key] =
       rawOptions[key] === undefined

From 8d68a9e3734d850e4c202f74c40d33cee054f1e4 Mon Sep 17 00:00:00 2001
From: HcySunYang <HcySunYang@outlook.com>
Date: Mon, 22 Mar 2021 10:29:27 +0800
Subject: [PATCH 4/5] chore: adjust the if branch

---
 packages/compiler-core/src/parse.ts | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/packages/compiler-core/src/parse.ts b/packages/compiler-core/src/parse.ts
index a76a0cd4c88..4bcf6c47198 100644
--- a/packages/compiler-core/src/parse.ts
+++ b/packages/compiler-core/src/parse.ts
@@ -241,9 +241,8 @@ function parseChildren(
         } else {
           node.content = node.content.replace(/[\t\r\n\f ]+/g, ' ')
         }
-      }
-      // comment nodes handling
-      if (node.type === NodeTypes.COMMENT && !context.options.comments) {
+      } else if (node.type === NodeTypes.COMMENT && !context.options.comments) {
+        // comment nodes handling
         removedWhitespace = true
         nodes[i] = null as any
       }

From f246ea81d70d2a16f2bcd925d6a218cafc28c8f2 Mon Sep 17 00:00:00 2001
From: HcySunYang <HcySunYang@outlook.com>
Date: Sun, 28 Mar 2021 13:36:38 +0800
Subject: [PATCH 5/5] chore: tweak comments

---
 packages/compiler-core/src/options.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/compiler-core/src/options.ts b/packages/compiler-core/src/options.ts
index d8d2573a6e8..2b9f87ca133 100644
--- a/packages/compiler-core/src/options.ts
+++ b/packages/compiler-core/src/options.ts
@@ -50,7 +50,7 @@ export interface ParserOptions {
   decodeEntities?: (rawText: string, asAttr: boolean) => string
   onError?: (error: CompilerError) => void
   /**
-   * Keep comments in the templates AST, even in production
+   * Whether to keep comments in the templates AST
    */
   comments?: boolean
 }