fix(43298): copy comments on converting from arrow function to anonymous function (#44236)

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;

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;
+}`
+});

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;
+}`
+});