Under jsx: preserve, actually preserve expressions which contain only comments (#41757)

* Under jsx: preserve, actually preserve expressions which contain only comments

* Even better best effort comment preservation in JSX comments

src/compiler/emitter.ts

@@ -2864,7 +2864,8 @@ namespace ts {
             }
             pos = writeTokenText(token, writer, pos);
             if (isSimilarNode && contextNode.end !== pos) {
-                emitTrailingCommentsOfPosition(pos, /*prefixSpace*/ true);
+                const isJsxExprContext = contextNode.kind === SyntaxKind.JsxExpression;
+                emitTrailingCommentsOfPosition(pos, /*prefixSpace*/ !isJsxExprContext, /*forceNoNewline*/ isJsxExprContext);
             }
             return pos;
         }
@@ -3421,12 +3422,35 @@ namespace ts {
             writePunctuation("}");
         }
 
+        function hasTrailingCommentsAtPosition(pos: number) {
+            let result = false;
+            forEachTrailingCommentRange(currentSourceFile?.text || "", pos + 1, () => result = true);
+            return result;
+        }
+
+        function hasLeadingCommentsAtPosition(pos: number) {
+            let result = false;
+            forEachLeadingCommentRange(currentSourceFile?.text || "", pos + 1, () => result = true);
+            return result;
+        }
+
+        function hasCommentsAtPosition(pos: number) {
+            return hasTrailingCommentsAtPosition(pos) || hasLeadingCommentsAtPosition(pos);
+        }
+
         function emitJsxExpression(node: JsxExpression) {
-            if (node.expression) {
-                writePunctuation("{");
+            if (node.expression || (!commentsDisabled && !nodeIsSynthesized(node) && hasCommentsAtPosition(node.pos))) { // preserve empty expressions if they contain comments!
+                const isMultiline = currentSourceFile && !nodeIsSynthesized(node) && getLineAndCharacterOfPosition(currentSourceFile, node.pos).line !== getLineAndCharacterOfPosition(currentSourceFile, node.end).line;
+                if (isMultiline) {
+                    writer.increaseIndent();
+                }
+                const end = emitTokenWithComment(SyntaxKind.OpenBraceToken, node.pos, writePunctuation, node);
                 emit(node.dotDotDotToken);
                 emitExpression(node.expression);
-                writePunctuation("}");
+                emitTokenWithComment(SyntaxKind.CloseBraceToken, node.expression?.end || end, writePunctuation, node);
+                if (isMultiline) {
+                    writer.decreaseIndent();
+                }
             }
         }
 
@@ -5274,15 +5298,27 @@ namespace ts {
             }
         }
 
-        function emitTrailingCommentsOfPosition(pos: number, prefixSpace?: boolean) {
+        function emitTrailingCommentsOfPosition(pos: number, prefixSpace?: boolean, forceNoNewline?: boolean) {
             if (commentsDisabled) {
                 return;
             }
             enterComment();
-            forEachTrailingCommentToEmit(pos, prefixSpace ? emitTrailingComment : emitTrailingCommentOfPosition);
+            forEachTrailingCommentToEmit(pos, prefixSpace ? emitTrailingComment : forceNoNewline ? emitTrailingCommentOfPositionNoNewline : emitTrailingCommentOfPosition);
             exitComment();
         }
 
+        function emitTrailingCommentOfPositionNoNewline(commentPos: number, commentEnd: number, kind: SyntaxKind) {
+            // trailing comments of a position are emitted at /*trailing comment1 */space/*trailing comment*/space
+
+            emitPos(commentPos);
+            writeCommentRange(currentSourceFile!.text, getCurrentLineMap(), writer, commentPos, commentEnd, newLine);
+            emitPos(commentEnd);
+
+            if (kind === SyntaxKind.SingleLineCommentTrivia) {
+                writer.writeLine(); // still write a newline for single-line comments, so closing tokens aren't written on the same line
+            }
+        }
+
         function emitTrailingCommentOfPosition(commentPos: number, commentEnd: number, _kind: SyntaxKind, hasTrailingNewLine: boolean) {
             // trailing comments of a position are emitted at /*trailing comment1 */space/*trailing comment*/space
 

src/compiler/transformers/module/module.ts

@@ -1790,7 +1790,7 @@ namespace ts {
                         const name = importDeclaration.propertyName || importDeclaration.name;
                         return setTextRange(
                             factory.createPropertyAccessExpression(
-                                factory.getGeneratedNameForNode(importDeclaration.parent.parent.parent),
+                                factory.getGeneratedNameForNode(importDeclaration.parent?.parent?.parent || importDeclaration),
                                 factory.cloneNode(name)
                             ),
                             /*location*/ node

src/compiler/transformers/module/system.ts

@@ -1678,7 +1678,7 @@ namespace ts {
                             factory.createPropertyAssignment(
                                 factory.cloneNode(name),
                                 factory.createPropertyAccessExpression(
-                                    factory.getGeneratedNameForNode(importDeclaration.parent.parent.parent),
+                                    factory.getGeneratedNameForNode(importDeclaration.parent?.parent?.parent || importDeclaration),
                                     factory.cloneNode(importDeclaration.propertyName || importDeclaration.name)
                                 ),
                             ),
@@ -1747,7 +1747,7 @@ namespace ts {
                     else if (isImportSpecifier(importDeclaration)) {
                         return setTextRange(
                             factory.createPropertyAccessExpression(
-                                factory.getGeneratedNameForNode(importDeclaration.parent.parent.parent),
+                                factory.getGeneratedNameForNode(importDeclaration.parent?.parent?.parent || importDeclaration),
                                 factory.cloneNode(importDeclaration.propertyName || importDeclaration.name)
                             ),
                             /*location*/ node

tests/baselines/reference/commentEmittingInPreserveJsx1.js

@@ -39,19 +39,21 @@ var React = require("react");
 </div>;
 <div>
     // Not Comment
-    
+    {
+    //Comment just Fine
+    }
     // Another not Comment
 </div>;
 <div>
     // Not Comment
     {
-//Comment just Fine
-"Hi"}
+    //Comment just Fine
+    "Hi"}
     // Another not Comment
 </div>;
 <div>
     /* Not Comment */
     {
-//Comment just Fine
-"Hi"}
+    //Comment just Fine
+    "Hi"}
 </div>;

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=preserve,module=commonjs).js

@@ -0,0 +1,44 @@
+//// [commentsOnJSXExpressionsArePreserved.tsx]
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+class Component {
+    render() {
+        return <div>
+            {/* missing */}
+            {null/* preserved */}
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+    }
+}
+
+//// [commentsOnJSXExpressionsArePreserved.jsx]
+var Component = /** @class */ (function () {
+    function Component() {
+    }
+    Component.prototype.render = function () {
+        return <div>
+            {/* missing */}
+            {null /* preserved */}
+            {
+            // ??? 1
+            }
+            {// ??? 2
+            }
+            {// ??? 3
+            }
+            {
+            // ??? 4
+            /* ??? 5 */ }
+        </div>;
+    };
+    return Component;
+}());

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=preserve,module=commonjs).symbols

@@ -0,0 +1,27 @@
+=== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx ===
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+>JSX : Symbol(JSX, Decl(commentsOnJSXExpressionsArePreserved.tsx, 0, 0))
+
+class Component {
+>Component : Symbol(Component, Decl(commentsOnJSXExpressionsArePreserved.tsx, 1, 16))
+
+    render() {
+>render : Symbol(Component.render, Decl(commentsOnJSXExpressionsArePreserved.tsx, 2, 17))
+
+        return <div>
+            {/* missing */}
+            {null/* preserved */}
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+    }
+}

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=preserve,module=commonjs).types

@@ -0,0 +1,30 @@
+=== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx ===
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+class Component {
+>Component : Component
+
+    render() {
+>render : () => any
+
+        return <div>
+><div>            {/* missing */}            {null/* preserved */}            {                // ??? 1            }            { // ??? 2            }            {// ??? 3            }            {                // ??? 4            /* ??? 5 */}        </div> : error
+>div : any
+
+            {/* missing */}
+            {null/* preserved */}
+>null : null
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+>div : any
+    }
+}

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=preserve,module=system).js

@@ -0,0 +1,44 @@
+//// [commentsOnJSXExpressionsArePreserved.tsx]
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+class Component {
+    render() {
+        return <div>
+            {/* missing */}
+            {null/* preserved */}
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+    }
+}
+
+//// [commentsOnJSXExpressionsArePreserved.jsx]
+var Component = /** @class */ (function () {
+    function Component() {
+    }
+    Component.prototype.render = function () {
+        return <div>
+            {/* missing */}
+            {null /* preserved */}
+            {
+            // ??? 1
+            }
+            {// ??? 2
+            }
+            {// ??? 3
+            }
+            {
+            // ??? 4
+            /* ??? 5 */ }
+        </div>;
+    };
+    return Component;
+}());

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=preserve,module=system).symbols

@@ -0,0 +1,27 @@
+=== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx ===
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+>JSX : Symbol(JSX, Decl(commentsOnJSXExpressionsArePreserved.tsx, 0, 0))
+
+class Component {
+>Component : Symbol(Component, Decl(commentsOnJSXExpressionsArePreserved.tsx, 1, 16))
+
+    render() {
+>render : Symbol(Component.render, Decl(commentsOnJSXExpressionsArePreserved.tsx, 2, 17))
+
+        return <div>
+            {/* missing */}
+            {null/* preserved */}
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+    }
+}

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=preserve,module=system).types

@@ -0,0 +1,30 @@
+=== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx ===
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+class Component {
+>Component : Component
+
+    render() {
+>render : () => any
+
+        return <div>
+><div>            {/* missing */}            {null/* preserved */}            {                // ??? 1            }            { // ??? 2            }            {// ??? 3            }            {                // ??? 4            /* ??? 5 */}        </div> : error
+>div : any
+
+            {/* missing */}
+            {null/* preserved */}
+>null : null
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+>div : any
+    }
+}

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react,module=commonjs).errors.txt

@@ -0,0 +1,26 @@
+tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx(5,17): error TS2304: Cannot find name 'React'.
+
+
+==== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx (1 errors) ====
+    // file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+    namespace JSX {}
+    class Component {
+        render() {
+            return <div>
+                    ~~~
+!!! error TS2304: Cannot find name 'React'.
+                {/* missing */}
+                {null/* preserved */}
+                {
+                    // ??? 1
+                }
+                { // ??? 2
+                }
+                {// ??? 3
+                }
+                {
+                    // ??? 4
+                /* ??? 5 */}
+            </div>;
+        }
+    }

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react,module=commonjs).js

@@ -0,0 +1,31 @@
+//// [commentsOnJSXExpressionsArePreserved.tsx]
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+class Component {
+    render() {
+        return <div>
+            {/* missing */}
+            {null/* preserved */}
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+    }
+}
+
+//// [commentsOnJSXExpressionsArePreserved.js]
+var Component = /** @class */ (function () {
+    function Component() {
+    }
+    Component.prototype.render = function () {
+        return React.createElement("div", null, null /* preserved */);
+    };
+    return Component;
+}());

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react,module=commonjs).symbols

@@ -0,0 +1,27 @@
+=== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx ===
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+>JSX : Symbol(JSX, Decl(commentsOnJSXExpressionsArePreserved.tsx, 0, 0))
+
+class Component {
+>Component : Symbol(Component, Decl(commentsOnJSXExpressionsArePreserved.tsx, 1, 16))
+
+    render() {
+>render : Symbol(Component.render, Decl(commentsOnJSXExpressionsArePreserved.tsx, 2, 17))
+
+        return <div>
+            {/* missing */}
+            {null/* preserved */}
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+    }
+}

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react,module=commonjs).types

@@ -0,0 +1,30 @@
+=== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx ===
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+class Component {
+>Component : Component
+
+    render() {
+>render : () => any
+
+        return <div>
+><div>            {/* missing */}            {null/* preserved */}            {                // ??? 1            }            { // ??? 2            }            {// ??? 3            }            {                // ??? 4            /* ??? 5 */}        </div> : any
+>div : any
+
+            {/* missing */}
+            {null/* preserved */}
+>null : null
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+>div : any
+    }
+}

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react,module=system).errors.txt

@@ -0,0 +1,26 @@
+tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx(5,17): error TS2304: Cannot find name 'React'.
+
+
+==== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx (1 errors) ====
+    // file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+    namespace JSX {}
+    class Component {
+        render() {
+            return <div>
+                    ~~~
+!!! error TS2304: Cannot find name 'React'.
+                {/* missing */}
+                {null/* preserved */}
+                {
+                    // ??? 1
+                }
+                { // ??? 2
+                }
+                {// ??? 3
+                }
+                {
+                    // ??? 4
+                /* ??? 5 */}
+            </div>;
+        }
+    }

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react,module=system).js

@@ -0,0 +1,31 @@
+//// [commentsOnJSXExpressionsArePreserved.tsx]
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+class Component {
+    render() {
+        return <div>
+            {/* missing */}
+            {null/* preserved */}
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+    }
+}
+
+//// [commentsOnJSXExpressionsArePreserved.js]
+var Component = /** @class */ (function () {
+    function Component() {
+    }
+    Component.prototype.render = function () {
+        return React.createElement("div", null, null /* preserved */);
+    };
+    return Component;
+}());

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react,module=system).symbols

@@ -0,0 +1,27 @@
+=== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx ===
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+>JSX : Symbol(JSX, Decl(commentsOnJSXExpressionsArePreserved.tsx, 0, 0))
+
+class Component {
+>Component : Symbol(Component, Decl(commentsOnJSXExpressionsArePreserved.tsx, 1, 16))
+
+    render() {
+>render : Symbol(Component.render, Decl(commentsOnJSXExpressionsArePreserved.tsx, 2, 17))
+
+        return <div>
+            {/* missing */}
+            {null/* preserved */}
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+    }
+}

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react,module=system).types

@@ -0,0 +1,30 @@
+=== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx ===
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+class Component {
+>Component : Component
+
+    render() {
+>render : () => any
+
+        return <div>
+><div>            {/* missing */}            {null/* preserved */}            {                // ??? 1            }            { // ??? 2            }            {// ??? 3            }            {                // ??? 4            /* ??? 5 */}        </div> : any
+>div : any
+
+            {/* missing */}
+            {null/* preserved */}
+>null : null
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+>div : any
+    }
+}

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react-jsx,module=commonjs).errors.txt

@@ -0,0 +1,39 @@
+tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx(5,16): error TS2307: Cannot find module 'react/jsx-runtime' or its corresponding type declarations.
+
+
+==== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx (1 errors) ====
+    // file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+    namespace JSX {}
+    class Component {
+        render() {
+            return <div>
+                   ~~~~~
+                {/* missing */}
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~
+                {null/* preserved */}
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+                {
+    ~~~~~~~~~~~~~
+                    // ??? 1
+    ~~~~~~~~~~~~~~~~~~~~~~~~
+                }
+    ~~~~~~~~~~~~~
+                { // ??? 2
+    ~~~~~~~~~~~~~~~~~~~~~~
+                }
+    ~~~~~~~~~~~~~
+                {// ??? 3
+    ~~~~~~~~~~~~~~~~~~~~~
+                }
+    ~~~~~~~~~~~~~
+                {
+    ~~~~~~~~~~~~~
+                    // ??? 4
+    ~~~~~~~~~~~~~~~~~~~~~~~~
+                /* ??? 5 */}
+    ~~~~~~~~~~~~~~~~~~~~~~~~
+            </div>;
+    ~~~~~~~~~~~~~~
+!!! error TS2307: Cannot find module 'react/jsx-runtime' or its corresponding type declarations.
+        }
+    }

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react-jsx,module=commonjs).js

@@ -0,0 +1,31 @@
+//// [commentsOnJSXExpressionsArePreserved.tsx]
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+class Component {
+    render() {
+        return <div>
+            {/* missing */}
+            {null/* preserved */}
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+    }
+}
+
+//// [commentsOnJSXExpressionsArePreserved.js]
+var Component = /** @class */ (function () {
+    function Component() {
+    }
+    Component.prototype.render = function () {
+        return _a.jsx("div", { children: null /* preserved */ }, void 0);
+    };
+    return Component;
+}());

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react-jsx,module=commonjs).symbols

@@ -0,0 +1,27 @@
+=== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx ===
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+>JSX : Symbol(JSX, Decl(commentsOnJSXExpressionsArePreserved.tsx, 0, 0))
+
+class Component {
+>Component : Symbol(Component, Decl(commentsOnJSXExpressionsArePreserved.tsx, 1, 16))
+
+    render() {
+>render : Symbol(Component.render, Decl(commentsOnJSXExpressionsArePreserved.tsx, 2, 17))
+
+        return <div>
+            {/* missing */}
+            {null/* preserved */}
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+    }
+}

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react-jsx,module=commonjs).types

@@ -0,0 +1,30 @@
+=== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx ===
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+class Component {
+>Component : Component
+
+    render() {
+>render : () => any
+
+        return <div>
+><div>            {/* missing */}            {null/* preserved */}            {                // ??? 1            }            { // ??? 2            }            {// ??? 3            }            {                // ??? 4            /* ??? 5 */}        </div> : any
+>div : any
+
+            {/* missing */}
+            {null/* preserved */}
+>null : null
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+>div : any
+    }
+}

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react-jsx,module=system).errors.txt

@@ -0,0 +1,39 @@
+tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx(5,16): error TS2792: Cannot find module 'react/jsx-runtime'. Did you mean to set the 'moduleResolution' option to 'node', or to add aliases to the 'paths' option?
+
+
+==== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx (1 errors) ====
+    // file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+    namespace JSX {}
+    class Component {
+        render() {
+            return <div>
+                   ~~~~~
+                {/* missing */}
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~
+                {null/* preserved */}
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+                {
+    ~~~~~~~~~~~~~
+                    // ??? 1
+    ~~~~~~~~~~~~~~~~~~~~~~~~
+                }
+    ~~~~~~~~~~~~~
+                { // ??? 2
+    ~~~~~~~~~~~~~~~~~~~~~~
+                }
+    ~~~~~~~~~~~~~
+                {// ??? 3
+    ~~~~~~~~~~~~~~~~~~~~~
+                }
+    ~~~~~~~~~~~~~
+                {
+    ~~~~~~~~~~~~~
+                    // ??? 4
+    ~~~~~~~~~~~~~~~~~~~~~~~~
+                /* ??? 5 */}
+    ~~~~~~~~~~~~~~~~~~~~~~~~
+            </div>;
+    ~~~~~~~~~~~~~~
+!!! error TS2792: Cannot find module 'react/jsx-runtime'. Did you mean to set the 'moduleResolution' option to 'node', or to add aliases to the 'paths' option?
+        }
+    }

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react-jsx,module=system).js

@@ -0,0 +1,31 @@
+//// [commentsOnJSXExpressionsArePreserved.tsx]
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+class Component {
+    render() {
+        return <div>
+            {/* missing */}
+            {null/* preserved */}
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+    }
+}
+
+//// [commentsOnJSXExpressionsArePreserved.js]
+var Component = /** @class */ (function () {
+    function Component() {
+    }
+    Component.prototype.render = function () {
+        return _jsx("div", { children: null /* preserved */ }, void 0);
+    };
+    return Component;
+}());

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react-jsx,module=system).symbols

@@ -0,0 +1,27 @@
+=== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx ===
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+>JSX : Symbol(JSX, Decl(commentsOnJSXExpressionsArePreserved.tsx, 0, 0))
+
+class Component {
+>Component : Symbol(Component, Decl(commentsOnJSXExpressionsArePreserved.tsx, 1, 16))
+
+    render() {
+>render : Symbol(Component.render, Decl(commentsOnJSXExpressionsArePreserved.tsx, 2, 17))
+
+        return <div>
+            {/* missing */}
+            {null/* preserved */}
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+    }
+}

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react-jsx,module=system).types

@@ -0,0 +1,30 @@
+=== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx ===
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+class Component {
+>Component : Component
+
+    render() {
+>render : () => any
+
+        return <div>
+><div>            {/* missing */}            {null/* preserved */}            {                // ??? 1            }            { // ??? 2            }            {// ??? 3            }            {                // ??? 4            /* ??? 5 */}        </div> : any
+>div : any
+
+            {/* missing */}
+            {null/* preserved */}
+>null : null
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+>div : any
+    }
+}

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react-jsxdev,module=commonjs).errors.txt

@@ -0,0 +1,39 @@
+tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx(5,16): error TS2307: Cannot find module 'react/jsx-dev-runtime' or its corresponding type declarations.
+
+
+==== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx (1 errors) ====
+    // file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+    namespace JSX {}
+    class Component {
+        render() {
+            return <div>
+                   ~~~~~
+                {/* missing */}
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~
+                {null/* preserved */}
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+                {
+    ~~~~~~~~~~~~~
+                    // ??? 1
+    ~~~~~~~~~~~~~~~~~~~~~~~~
+                }
+    ~~~~~~~~~~~~~
+                { // ??? 2
+    ~~~~~~~~~~~~~~~~~~~~~~
+                }
+    ~~~~~~~~~~~~~
+                {// ??? 3
+    ~~~~~~~~~~~~~~~~~~~~~
+                }
+    ~~~~~~~~~~~~~
+                {
+    ~~~~~~~~~~~~~
+                    // ??? 4
+    ~~~~~~~~~~~~~~~~~~~~~~~~
+                /* ??? 5 */}
+    ~~~~~~~~~~~~~~~~~~~~~~~~
+            </div>;
+    ~~~~~~~~~~~~~~
+!!! error TS2307: Cannot find module 'react/jsx-dev-runtime' or its corresponding type declarations.
+        }
+    }

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react-jsxdev,module=commonjs).js

@@ -0,0 +1,32 @@
+//// [commentsOnJSXExpressionsArePreserved.tsx]
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+class Component {
+    render() {
+        return <div>
+            {/* missing */}
+            {null/* preserved */}
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+    }
+}
+
+//// [commentsOnJSXExpressionsArePreserved.js]
+var _jsxFileName = "tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx";
+var Component = /** @class */ (function () {
+    function Component() {
+    }
+    Component.prototype.render = function () {
+        return _a.jsxDEV("div", { children: null /* preserved */ }, void 0, false, { fileName: _jsxFileName, lineNumber: 5, columnNumber: 15 }, this);
+    };
+    return Component;
+}());

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react-jsxdev,module=commonjs).symbols

@@ -0,0 +1,27 @@
+=== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx ===
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+>JSX : Symbol(JSX, Decl(commentsOnJSXExpressionsArePreserved.tsx, 0, 0))
+
+class Component {
+>Component : Symbol(Component, Decl(commentsOnJSXExpressionsArePreserved.tsx, 1, 16))
+
+    render() {
+>render : Symbol(Component.render, Decl(commentsOnJSXExpressionsArePreserved.tsx, 2, 17))
+
+        return <div>
+            {/* missing */}
+            {null/* preserved */}
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+    }
+}

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react-jsxdev,module=commonjs).types

@@ -0,0 +1,30 @@
+=== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx ===
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+class Component {
+>Component : Component
+
+    render() {
+>render : () => any
+
+        return <div>
+><div>            {/* missing */}            {null/* preserved */}            {                // ??? 1            }            { // ??? 2            }            {// ??? 3            }            {                // ??? 4            /* ??? 5 */}        </div> : any
+>div : any
+
+            {/* missing */}
+            {null/* preserved */}
+>null : null
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+>div : any
+    }
+}

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react-jsxdev,module=system).errors.txt

@@ -0,0 +1,39 @@
+tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx(5,16): error TS2792: Cannot find module 'react/jsx-dev-runtime'. Did you mean to set the 'moduleResolution' option to 'node', or to add aliases to the 'paths' option?
+
+
+==== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx (1 errors) ====
+    // file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+    namespace JSX {}
+    class Component {
+        render() {
+            return <div>
+                   ~~~~~
+                {/* missing */}
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~
+                {null/* preserved */}
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+                {
+    ~~~~~~~~~~~~~
+                    // ??? 1
+    ~~~~~~~~~~~~~~~~~~~~~~~~
+                }
+    ~~~~~~~~~~~~~
+                { // ??? 2
+    ~~~~~~~~~~~~~~~~~~~~~~
+                }
+    ~~~~~~~~~~~~~
+                {// ??? 3
+    ~~~~~~~~~~~~~~~~~~~~~
+                }
+    ~~~~~~~~~~~~~
+                {
+    ~~~~~~~~~~~~~
+                    // ??? 4
+    ~~~~~~~~~~~~~~~~~~~~~~~~
+                /* ??? 5 */}
+    ~~~~~~~~~~~~~~~~~~~~~~~~
+            </div>;
+    ~~~~~~~~~~~~~~
+!!! error TS2792: Cannot find module 'react/jsx-dev-runtime'. Did you mean to set the 'moduleResolution' option to 'node', or to add aliases to the 'paths' option?
+        }
+    }

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react-jsxdev,module=system).js

@@ -0,0 +1,32 @@
+//// [commentsOnJSXExpressionsArePreserved.tsx]
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+class Component {
+    render() {
+        return <div>
+            {/* missing */}
+            {null/* preserved */}
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+    }
+}
+
+//// [commentsOnJSXExpressionsArePreserved.js]
+var _jsxFileName = "tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx";
+var Component = /** @class */ (function () {
+    function Component() {
+    }
+    Component.prototype.render = function () {
+        return _jsxDEV("div", { children: null /* preserved */ }, void 0, false, { fileName: _jsxFileName, lineNumber: 5, columnNumber: 15 }, this);
+    };
+    return Component;
+}());

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react-jsxdev,module=system).symbols

@@ -0,0 +1,27 @@
+=== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx ===
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+>JSX : Symbol(JSX, Decl(commentsOnJSXExpressionsArePreserved.tsx, 0, 0))
+
+class Component {
+>Component : Symbol(Component, Decl(commentsOnJSXExpressionsArePreserved.tsx, 1, 16))
+
+    render() {
+>render : Symbol(Component.render, Decl(commentsOnJSXExpressionsArePreserved.tsx, 2, 17))
+
+        return <div>
+            {/* missing */}
+            {null/* preserved */}
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+    }
+}

tests/baselines/reference/commentsOnJSXExpressionsArePreserved(jsx=react-jsxdev,module=system).types

@@ -0,0 +1,30 @@
+=== tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx ===
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+class Component {
+>Component : Component
+
+    render() {
+>render : () => any
+
+        return <div>
+><div>            {/* missing */}            {null/* preserved */}            {                // ??? 1            }            { // ??? 2            }            {// ??? 3            }            {                // ??? 4            /* ??? 5 */}        </div> : any
+>div : any
+
+            {/* missing */}
+            {null/* preserved */}
+>null : null
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+>div : any
+    }
+}

tests/baselines/reference/jsxAndTypeAssertion.js

@@ -40,9 +40,9 @@ x = <foo test={<foo>}>hello{<foo>}</foo>};
 
 x = <foo>x</foo>, x = <foo />;
 
-<foo>{<foo><foo>{/foo/.test(x) ? <foo><foo></foo> : <foo><foo></foo>}</foo>}</foo>
-    :
-}
+    <foo>{<foo><foo>{/foo/.test(x) ? <foo><foo></foo> : <foo><foo></foo>}</foo>}</foo>
+            :
+        }
 
     
-</></>}</></>}/></></></>;
+        </></>}</></>}/></></></>;

tests/baselines/reference/jsxEsprimaFbTestSuite.js

@@ -69,7 +69,7 @@ baz
 </AbC_def>;
 <a b={x ? <c /> : <d />}/>;
 <a></a>;
-<a></a>;
+<a>{/* this is a comment */}</a>;
 <div>@test content</div>;
 <div><br />7x invalid-js-identifier</div>;
 <LeftRight left/>, <a />;

tests/baselines/reference/jsxNestedWithinTernaryParsesCorrectly.js

@@ -17,9 +17,9 @@ const a = (
 var emptyMessage = null;
 var a = (<div>
       {0 ? (emptyMessage // must be identifier?
-) : (
-// must be exactly two expression holes
-<span>
+    ) : (
+    // must be exactly two expression holes
+    <span>
           {0}{0}
         </span>)}
     </div>);

tests/baselines/reference/jsxReactTestSuite.js

@@ -133,19 +133,21 @@ var x =
     <Composite2 />
 </Composite>;
 var x = <div attr1={"foo" + "bar"} attr2={"foo" + "bar" +
-    "baz" + "bug"} attr3={"foo" + "bar" +
-    "baz" + "bug"} attr4="baz">
+        "baz" + "bug"} attr3={"foo" + "bar" +
+        "baz" + "bug"
+    // Extra line here.
+    } attr4="baz">
   </div>;
 (<div>
-    
-    
+    {/* A comment at the beginning */}
+    {/* A second comment at the beginning */}
     <span>
-      
+      {/* A nested comment */}
     </span>
-    
+    {/* A sandwiched comment */}
     <br />
-    
-    
+    {/* A comment at the end */}
+    {/* A second comment at the end */}
   </div>);
 (<div 
 /* a multi-line

tests/baselines/reference/tsxTypeArgumentsJsxPreserveOutput.js

@@ -43,7 +43,7 @@ function Foo() {
     return null;
 }
 <>
-    
+    {/* JsxSelfClosingElement */}
     <Foo />
     <Foo />
     <Foo />
@@ -55,7 +55,7 @@ function Foo() {
     <Foo />
     <Foo />
 
-    
+    {/* JsxOpeningElement */}
     <Foo></Foo>
     <Foo></Foo>
     <Foo></Foo>

tests/cases/compiler/commentsOnJSXExpressionsArePreserved.tsx

@@ -0,0 +1,22 @@
+// @module: system,commonjs
+// @jsx: react,react-jsx,react-jsxdev,preserve
+// file is intentionally not a module - this tests for a crash in the module/system transforms alongside the `react-jsx` and `react-jsxdev` outputs
+namespace JSX {}
+class Component {
+    render() {
+        return <div>
+            {/* missing */}
+            {null/* preserved */}
+            {
+                // ??? 1
+            }
+            { // ??? 2
+            }
+            {// ??? 3
+            }
+            {
+                // ??? 4
+            /* ??? 5 */}
+        </div>;
+    }
+}