Merge pull request #13916 from Microsoft/master-fix13602

[Master] Fix 13602 preserve comment following element in node list

Author: yuit

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;
+        emitLeadingCommentsOfPosition(pos: number): void;
     }
 
     export function createCommentWriter(printerOptions: PrinterOptions, emitPos: ((pos: number) => void) | undefined): CommentWriter {
@@ -32,6 +33,7 @@ namespace ts {
             emitNodeWithComments,
             emitBodyWithDetachedComments,
             emitTrailingCommentsOfPosition,
+            emitLeadingCommentsOfPosition,
         };
 
         function emitNodeWithComments(hint: EmitHint, node: Node, emitCallback: (hint: EmitHint, node: Node) => void) {
@@ -210,6 +212,14 @@ namespace ts {
             }
         }
 
+        function emitLeadingCommentsOfPosition(pos: number) {
+            if (disabled || pos === -1) {
+                return;
+            }
+
+            emitLeadingComments(pos, /*isEmittedNode*/ true);
+        }
+
         function emitTrailingComments(pos: number) {
             forEachTrailingCommentToEmit(pos, emitTrailingComment);
         }

src/compiler/emitter.ts

@@ -1,4 +1,4 @@
-/// <reference path="checker.ts" />
+/// <reference path="checker.ts" />
 /// <reference path="transformer.ts" />
 /// <reference path="declarationEmitter.ts" />
 /// <reference path="sourcemap.ts" />
@@ -211,6 +211,7 @@ namespace ts {
             emitNodeWithComments,
             emitBodyWithDetachedComments,
             emitTrailingCommentsOfPosition,
+            emitLeadingCommentsOfPosition,
         } = comments;
 
         let currentSourceFile: SourceFile;
@@ -1346,6 +1347,10 @@ namespace ts {
             else {
                 writeToken(SyntaxKind.OpenBraceToken, node.pos, /*contextNode*/ node);
                 emitBlockStatements(node);
+                // We have to call emitLeadingComments explicitly here because otherwise leading comments of the close brace token will not be emitted
+                increaseIndent();
+                emitLeadingCommentsOfPosition(node.statements.end);
+                decreaseIndent();
                 writeToken(SyntaxKind.CloseBraceToken, node.statements.end, /*contextNode*/ node);
             }
         }
@@ -2228,6 +2233,15 @@ 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 isn't considered to be trailing comment of parameter "a" due to newline
+                        //          ,
+                        if (delimiter && previousSibling.end !== parentNode.end) {
+                            emitLeadingCommentsOfPosition(previousSibling.end);
+                        }
                         write(delimiter);
 
                         // Write either a line terminator or whitespace to separate the elements.
@@ -2274,6 +2288,17 @@ 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) {
+                    emitLeadingCommentsOfPosition(previousSibling.end);
+                }
+
                 // Decrease the indent, if requested.
                 if (format & ListFormat.Indented) {
                     decreaseIndent();

tests/baselines/reference/amdImportAsPrimaryExpression.js

@@ -26,5 +26,6 @@ define(["require", "exports"], function (require, exports) {
 define(["require", "exports", "./foo_0"], function (require, exports, foo) {
     "use strict";
     if (foo.E1.A === 0) {
+        // Should cause runtime import - interesting optimization possibility, as gets inlined to 0.
     }
 });

tests/baselines/reference/argsInScope.js

@@ -17,6 +17,7 @@ var C = (function () {
     }
     C.prototype.P = function (ii, j, k) {
         for (var i = 0; i < arguments.length; i++) {
+            // WScript.Echo("param: " + arguments[i]);
         }
     };
     return C;

tests/baselines/reference/arrowFunctionErrorSpan.js

@@ -83,7 +83,9 @@ f(// comment 1
 // comment 2
 function () {
     // comment 4
-});
+}
+// comment 5
+);
 // body is not a block
 f(function (_) { return 1 +
     2; });

tests/baselines/reference/commentLeadingCloseBrace.js

@@ -0,0 +1,24 @@
+//// [commentLeadingCloseBrace.ts]
+declare function commentedParameters(...args): any;
+
+function ifelse() {
+    if (commentedParameters(1, 2)) {
+        /*comment1*/
+        commentedParameters(3, 4);
+        /*comment2*/
+    } else {
+        commentedParameters(5, 6);
+    }
+}
+
+//// [commentLeadingCloseBrace.js]
+function ifelse() {
+    if (commentedParameters(1, 2)) {
+        /*comment1*/
+        commentedParameters(3, 4);
+        /*comment2*/
+    }
+    else {
+        commentedParameters(5, 6);
+    }
+}

tests/baselines/reference/commentLeadingCloseBrace.symbols

@@ -0,0 +1,21 @@
+=== tests/cases/compiler/commentLeadingCloseBrace.ts ===
+declare function commentedParameters(...args): any;
+>commentedParameters : Symbol(commentedParameters, Decl(commentLeadingCloseBrace.ts, 0, 0))
+>args : Symbol(args, Decl(commentLeadingCloseBrace.ts, 0, 37))
+
+function ifelse() {
+>ifelse : Symbol(ifelse, Decl(commentLeadingCloseBrace.ts, 0, 51))
+
+    if (commentedParameters(1, 2)) {
+>commentedParameters : Symbol(commentedParameters, Decl(commentLeadingCloseBrace.ts, 0, 0))
+
+        /*comment1*/
+        commentedParameters(3, 4);
+>commentedParameters : Symbol(commentedParameters, Decl(commentLeadingCloseBrace.ts, 0, 0))
+
+        /*comment2*/
+    } else {
+        commentedParameters(5, 6);
+>commentedParameters : Symbol(commentedParameters, Decl(commentLeadingCloseBrace.ts, 0, 0))
+    }
+}

tests/baselines/reference/commentLeadingCloseBrace.types

@@ -0,0 +1,30 @@
+=== tests/cases/compiler/commentLeadingCloseBrace.ts ===
+declare function commentedParameters(...args): any;
+>commentedParameters : (...args: any[]) => any
+>args : any[]
+
+function ifelse() {
+>ifelse : () => void
+
+    if (commentedParameters(1, 2)) {
+>commentedParameters(1, 2) : any
+>commentedParameters : (...args: any[]) => any
+>1 : 1
+>2 : 2
+
+        /*comment1*/
+        commentedParameters(3, 4);
+>commentedParameters(3, 4) : any
+>commentedParameters : (...args: any[]) => any
+>3 : 3
+>4 : 4
+
+        /*comment2*/
+    } else {
+        commentedParameters(5, 6);
+>commentedParameters(5, 6) : any
+>commentedParameters : (...args: any[]) => any
+>5 : 5
+>6 : 6
+    }
+}

tests/baselines/reference/commentOnArrayElement1.js

@@ -0,0 +1,17 @@
+//// [commentOnArrayElement1.ts]
+var array = [
+    /* element 1*/
+    1
+    /* end of element 1 */,
+    2
+    /* end of element 2 */
+];
+
+//// [commentOnArrayElement1.js]
+var array = [
+    /* element 1*/
+    1
+    /* end of element 1 */ ,
+    2
+    /* end of element 2 */
+];

tests/baselines/reference/commentOnArrayElement1.symbols

@@ -0,0 +1,10 @@
+=== tests/cases/compiler/commentOnArrayElement1.ts ===
+var array = [
+>array : Symbol(array, Decl(commentOnArrayElement1.ts, 0, 3))
+
+    /* element 1*/
+    1
+    /* end of element 1 */,
+    2
+    /* end of element 2 */
+];