Emit missing trailing comment of an element in node list

Kanchalai Tanglertsampan · Kanchalai Tanglertsampan · commit 188e9df9b55d · 2017-02-06T18:13:17.000-08:00
diff --git a/src/compiler/comments.ts b/src/compiler/comments.ts
@@ -9,6 +9,7 @@ namespace ts {
         emitNodeWithComments(hint: EmitHint, node: Node, emitCallback: (hint: EmitHint, node: Node) => void): void;
         emitBodyWithDetachedComments(node: Node, detachedRange: TextRange, emitCallback: (node: Node) => void): void;
         emitTrailingCommentsOfPosition(pos: number): void;
+        emitLeadingComments(pos: number, isEmittedNode: boolean): void;
     }
 
     export function createCommentWriter(printerOptions: PrinterOptions, emitPos: ((pos: number) => void) | undefined): CommentWriter {
@@ -32,6 +33,7 @@ namespace ts {
             emitNodeWithComments,
             emitBodyWithDetachedComments,
             emitTrailingCommentsOfPosition,
+            emitLeadingComments,
         };
 
         function emitNodeWithComments(hint: EmitHint, node: Node, emitCallback: (hint: EmitHint, node: Node) => void) {
@@ -167,6 +169,10 @@ namespace ts {
         }
 
         function emitLeadingComments(pos: number, isEmittedNode: boolean) {
+            if (disabled) {
+                return;
+            }
+
             hasWrittenComment = false;
 
             if (isEmittedNode) {
diff --git a/src/compiler/emitter.ts b/src/compiler/emitter.ts
@@ -211,6 +211,7 @@ namespace ts {
             emitNodeWithComments,
             emitBodyWithDetachedComments,
             emitTrailingCommentsOfPosition,
+            emitLeadingComments,
         } = comments;
 
         let currentSourceFile: SourceFile;
@@ -2228,6 +2229,15 @@ namespace ts {
 
                     // Write the delimiter if this is not the first node.
                     if (previousSibling) {
+                        // i.e
+                        //      function commentedParameters(
+                        //          /* Parameter a */
+                        //          a
+                        //          /* End of parameter a */ -> this comment doesn't consider to be trailing comment of parameter "a" due to newline
+                        //          ,
+                        if (emitLeadingComments && delimiter && previousSibling.end !== parentNode.end) {
+                            emitLeadingComments(previousSibling.end, /*isEmittedNode*/ previousSibling.kind !== SyntaxKind.NotEmittedStatement);
+                        }
                         write(delimiter);
 
                         // Write either a line terminator or whitespace to separate the elements.
@@ -2274,6 +2284,20 @@ namespace ts {
                     write(",");
                 }
 
+
+                // Emit any trailing comment of the last element in the list
+                // i.e
+                //       var array = [...
+                //          2
+                //          /* end of element 2 */
+                //       ];
+                if (previousSibling && delimiter && previousSibling.end !== parentNode.end) {
+                    emitLeadingComments(previousSibling.end, /*isEmittedNode*/ previousSibling.kind !== SyntaxKind.NotEmittedStatement);
+                    if (hasTrailingComma) {
+                        emitLeadingComments(previousSibling.end,  /*isEmittedNode*/ previousSibling.kind !== SyntaxKind.NotEmittedStatement);
+                    }
+                }
+
                 // Decrease the indent, if requested.
                 if (format & ListFormat.Indented) {
                     decreaseIndent();
