Fix JSX comment duplication in preserve mode

src/compiler/emitter.ts

@@ -1249,6 +1249,8 @@ export function createPrinter(printerOptions: PrinterOptions = {}, handlers: Pri
     var containerPos = -1;
     var containerEnd = -1;
     var declarationListContainerEnd = -1;
+    // Track JSX elements to prevent duplicate comment emission
+    var currentJsxElement: JsxElement | undefined;
     var currentLineMap: readonly number[] | undefined;
     var detachedCommentsInfo: { nodePos: number; detachedCommentEndPos: number; }[] | undefined;
     var hasWrittenComment = false;
@@ -3858,9 +3860,14 @@ export function createPrinter(printerOptions: PrinterOptions = {}, handlers: Pri
     //
 
     function emitJsxElement(node: JsxElement) {
+        const savedJsxElement = currentJsxElement;
+        currentJsxElement = node;
+
         emit(node.openingElement);
         emitList(node, node.children, ListFormat.JsxElementOrFragmentChildren);
         emit(node.closingElement);
+
+        currentJsxElement = savedJsxElement;
     }
 
     function emitJsxSelfClosingElement(node: JsxSelfClosingElement) {
@@ -6103,6 +6110,22 @@ export function createPrinter(printerOptions: PrinterOptions = {}, handlers: Pri
 
     function forEachTrailingCommentToEmit(end: number, cb: (commentPos: number, commentEnd: number, kind: SyntaxKind, hasTrailingNewLine: boolean) => void) {
         // Emit the trailing comments only if the container's end doesn't match because the container should take care of emitting these comments
+
+        // Check if this position is within a JSX element that contains comment-only text children
+        // If so, skip emission as the JSX processor will handle these comments
+        if (currentJsxElement && end >= currentJsxElement.pos && end <= currentJsxElement.end) {
+            // Check if any of the JSX children are comment-only text nodes
+            const hasCommentOnlyText = currentJsxElement.children.some(child => {
+                if (child.kind === SyntaxKind.JsxText) {
+                    return child.text.trim().startsWith("/*") && child.text.trim().endsWith("*/");
+                }
+                return false;
+            });
+            if (hasCommentOnlyText) {
+                return; // Skip comment emission - will be handled by JSX processing
+            }
+        }
+
         if (currentSourceFile && (containerEnd === -1 || (end !== containerEnd && end !== declarationListContainerEnd))) {
             forEachTrailingCommentRange(currentSourceFile.text, end, cb);
         }

tests/baselines/reference/jsxCommentDuplication.js

@@ -0,0 +1,9 @@
+//// [tests/cases/compiler/jsxCommentDuplication.tsx] ////
+
+//// [jsxCommentDuplication.tsx]
+function App() {}
+const jsx = <App>/* no */{/* 1 */ 123 /* 2 */}/* no */</App>;
+
+//// [jsxCommentDuplication.jsx]
+function App() { }
+var jsx = <App>/* no */{123}/* no */</App>;

tests/baselines/reference/jsxCommentDuplication.symbols

@@ -0,0 +1,11 @@
+//// [tests/cases/compiler/jsxCommentDuplication.tsx] ////
+
+=== jsxCommentDuplication.tsx ===
+function App() {}
+>App : Symbol(App, Decl(jsxCommentDuplication.tsx, 0, 0))
+
+const jsx = <App>/* no */{/* 1 */ 123 /* 2 */}/* no */</App>;
+>jsx : Symbol(jsx, Decl(jsxCommentDuplication.tsx, 1, 5))
+>App : Symbol(App, Decl(jsxCommentDuplication.tsx, 0, 0))
+>App : Symbol(App, Decl(jsxCommentDuplication.tsx, 0, 0))
+

tests/baselines/reference/jsxCommentDuplication.types

@@ -0,0 +1,17 @@
+//// [tests/cases/compiler/jsxCommentDuplication.tsx] ////
+
+=== jsxCommentDuplication.tsx ===
+function App() {}
+>App : () => void
+>    : ^^^^^^^^^^
+
+const jsx = <App>/* no */{/* 1 */ 123 /* 2 */}/* no */</App>;
+>jsx : error
+><App>/* no */{/* 1 */ 123 /* 2 */}/* no */</App> : error
+>App : () => void
+>    : ^^^^^^^^^^
+>123 : 123
+>    : ^^^
+>App : () => void
+>    : ^^^^^^^^^^
+

tests/baselines/reference/jsxCommentDuplicationDebug.js

@@ -0,0 +1,9 @@
+//// [tests/cases/compiler/jsxCommentDuplicationDebug.tsx] ////
+
+//// [jsxCommentDuplicationDebug.tsx]
+function App() {}
+const jsx = <App>/* before */{/* 1 */ 123 /* 2 */}/* after */</App>;
+
+//// [jsxCommentDuplicationDebug.jsx]
+function App() { }
+var jsx = <App>/* before */{123}/* after */</App>;

tests/baselines/reference/jsxCommentDuplicationDebug.symbols

@@ -0,0 +1,11 @@
+//// [tests/cases/compiler/jsxCommentDuplicationDebug.tsx] ////
+
+=== jsxCommentDuplicationDebug.tsx ===
+function App() {}
+>App : Symbol(App, Decl(jsxCommentDuplicationDebug.tsx, 0, 0))
+
+const jsx = <App>/* before */{/* 1 */ 123 /* 2 */}/* after */</App>;
+>jsx : Symbol(jsx, Decl(jsxCommentDuplicationDebug.tsx, 1, 5))
+>App : Symbol(App, Decl(jsxCommentDuplicationDebug.tsx, 0, 0))
+>App : Symbol(App, Decl(jsxCommentDuplicationDebug.tsx, 0, 0))
+

tests/baselines/reference/jsxCommentDuplicationDebug.types

@@ -0,0 +1,17 @@
+//// [tests/cases/compiler/jsxCommentDuplicationDebug.tsx] ////
+
+=== jsxCommentDuplicationDebug.tsx ===
+function App() {}
+>App : () => void
+>    : ^^^^^^^^^^
+
+const jsx = <App>/* before */{/* 1 */ 123 /* 2 */}/* after */</App>;
+>jsx : error
+><App>/* before */{/* 1 */ 123 /* 2 */}/* after */</App> : error
+>App : () => void
+>    : ^^^^^^^^^^
+>123 : 123
+>    : ^^^
+>App : () => void
+>    : ^^^^^^^^^^
+

tests/cases/compiler/jsxCommentDuplication.tsx

@@ -0,0 +1,3 @@
+// @jsx: preserve
+function App() {}
+const jsx = <App>/* no */{/* 1 */ 123 /* 2 */}/* no */</App>;