From f79b471b76e808bb8f814cddcdefea0d5c349515 Mon Sep 17 00:00:00 2001
From: Oleksandr T <oleksandr.tarasiuk@outlook.com>
Date: Tue, 18 May 2021 07:46:48 +0300
Subject: [PATCH] fix(43298): copy comments on converting from arrow function
 to anonymous function

---
 ...onvertArrowFunctionOrFunctionExpression.ts |  6 +++++-
 ...FunctionExpression_ToAnonymous_Comment1.ts | 19 +++++++++++++++++++
 ...FunctionExpression_ToAnonymous_Comment2.ts | 15 +++++++++++++++
 3 files changed, 39 insertions(+), 1 deletion(-)
 create mode 100644 tests/cases/fourslash/refactorConvertArrowFunctionOrFunctionExpression_ToAnonymous_Comment1.ts
 create mode 100644 tests/cases/fourslash/refactorConvertArrowFunctionOrFunctionExpression_ToAnonymous_Comment2.ts

diff --git a/src/services/refactors/convertArrowFunctionOrFunctionExpression.ts b/src/services/refactors/convertArrowFunctionOrFunctionExpression.ts
index 6987fdd491911..75cf29f9d79fe 100644
--- a/src/services/refactors/convertArrowFunctionOrFunctionExpression.ts
+++ b/src/services/refactors/convertArrowFunctionOrFunctionExpression.ts
@@ -177,7 +177,11 @@ namespace ts.refactor.convertArrowFunctionOrFunctionExpression {
 
     function convertToBlock(body: ConciseBody): Block {
         if (isExpression(body)) {
-            return factory.createBlock([factory.createReturnStatement(body)], /* multiLine */ true);
+            const returnStatement = factory.createReturnStatement(body);
+            const file = body.getSourceFile();
+            suppressLeadingAndTrailingTrivia(returnStatement);
+            copyTrailingAsLeadingComments(body, returnStatement, file, /* commentKind */ undefined, /* hasTrailingNewLine */ true);
+            return factory.createBlock([returnStatement], /* multiLine */ true);
         }
         else {
             return body;
diff --git a/tests/cases/fourslash/refactorConvertArrowFunctionOrFunctionExpression_ToAnonymous_Comment1.ts b/tests/cases/fourslash/refactorConvertArrowFunctionOrFunctionExpression_ToAnonymous_Comment1.ts
new file mode 100644
index 0000000000000..2acda7909b52a
--- /dev/null
+++ b/tests/cases/fourslash/refactorConvertArrowFunctionOrFunctionExpression_ToAnonymous_Comment1.ts
@@ -0,0 +1,19 @@
+/// <reference path='fourslash.ts' />
+
+////const foo = /*a*/()/*b*/ => /**
+//// * comment
+//// */
+////1
+
+goTo.select("a", "b");
+edit.applyRefactor({
+    refactorName: "Convert arrow function or function expression",
+    actionName: "Convert to anonymous function",
+    actionDescription: "Convert to anonymous function",
+    newContent: `const foo = function() {
+    /**
+     * comment
+     */
+    return 1;
+}`
+});
diff --git a/tests/cases/fourslash/refactorConvertArrowFunctionOrFunctionExpression_ToAnonymous_Comment2.ts b/tests/cases/fourslash/refactorConvertArrowFunctionOrFunctionExpression_ToAnonymous_Comment2.ts
new file mode 100644
index 0000000000000..8790718d61b13
--- /dev/null
+++ b/tests/cases/fourslash/refactorConvertArrowFunctionOrFunctionExpression_ToAnonymous_Comment2.ts
@@ -0,0 +1,15 @@
+/// <reference path='fourslash.ts' />
+
+////const foo = /*a*/()/*b*/ => // comment
+////1
+
+goTo.select("a", "b");
+edit.applyRefactor({
+    refactorName: "Convert arrow function or function expression",
+    actionName: "Convert to anonymous function",
+    actionDescription: "Convert to anonymous function",
+    newContent: `const foo = function() {
+    // comment
+    return 1;
+}`
+});