Don't substitute namespace exported names in JSX intrinsic tag names

src/compiler/checker.ts

@@ -640,6 +640,7 @@ import {
     isJsxCallLike,
     isJsxElement,
     isJsxFragment,
+    isJsxIntrinsicTagName,
     isJsxNamespacedName,
     isJsxOpeningElement,
     isJsxOpeningFragment,
@@ -833,7 +834,6 @@ import {
     JsxExpression,
     JsxFlags,
     JsxFragment,
-    JsxNamespacedName,
     JsxOpeningElement,
     JsxOpeningFragment,
     JsxOpeningLikeElement,
@@ -33099,13 +33099,6 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         return (name as string).includes("-");
     }
 
-    /**
-     * Returns true iff React would emit this tag name as a string rather than an identifier or qualified name
-     */
-    function isJsxIntrinsicTagName(tagName: Node): tagName is Identifier | JsxNamespacedName {
-        return isIdentifier(tagName) && isIntrinsicJsxName(tagName.escapedText) || isJsxNamespacedName(tagName);
-    }
-
     function checkJsxAttribute(node: JsxAttribute, checkMode?: CheckMode) {
         return node.initializer
             ? checkExpressionForMutableLocation(node.initializer, checkMode)

src/compiler/transformers/ts.ts

@@ -103,6 +103,8 @@ import {
     isInstantiatedModule,
     isJsonSourceFile,
     isJsxAttributes,
+    isJsxIntrinsicTagName,
+    isJSXTagName,
     isJsxTagNameExpression,
     isLeftHandSideExpression,
     isLocalName,
@@ -2688,8 +2690,10 @@ export function transformTypeScript(context: TransformationContext): Transformer
             // an identifier that is exported from a merged namespace.
             const container = resolver.getReferencedExportContainer(node, /*prefixLocals*/ false);
             if (container && container.kind !== SyntaxKind.SourceFile) {
-                const substitute = (applicableSubstitutions & TypeScriptSubstitutionFlags.NamespaceExports && container.kind === SyntaxKind.ModuleDeclaration) ||
-                    (applicableSubstitutions & TypeScriptSubstitutionFlags.NonQualifiedEnumMembers && container.kind === SyntaxKind.EnumDeclaration);
+                let originalNode;
+                const substitute = ((applicableSubstitutions & TypeScriptSubstitutionFlags.NamespaceExports && container.kind === SyntaxKind.ModuleDeclaration) ||
+                    (applicableSubstitutions & TypeScriptSubstitutionFlags.NonQualifiedEnumMembers && container.kind === SyntaxKind.EnumDeclaration)) &&
+                    (!isJSXTagName(originalNode = getOriginalNode(node, isIdentifier)) || !isJsxIntrinsicTagName(originalNode));
                 if (substitute) {
                     return setTextRange(
                         factory.createPropertyAccessExpression(factory.getGeneratedNameForNode(container), node),

src/compiler/utilities.ts

@@ -3549,6 +3549,14 @@ export function isJSXTagName(node: Node): boolean {
     return false;
 }
 
+/**
+ * @internal
+ * Returns true if React would emit this tag name as a string rather than an identifier or qualified name
+ */
+export function isJsxIntrinsicTagName(tagName: Node): tagName is Identifier | JsxNamespacedName {
+    return isIdentifier(tagName) && isIntrinsicJsxName(tagName.escapedText) || isJsxNamespacedName(tagName);
+}
+
 /** @internal */
 export function isExpressionNode(node: Node): boolean {
     switch (node.kind) {

tests/baselines/reference/namespaceJsxPreserve1.js

@@ -0,0 +1,27 @@
+//// [tests/cases/compiler/namespaceJsxPreserve1.tsx] ////
+
+//// [namespaceJsxPreserve1.tsx]
+/// <reference path="/.lib/react16.d.ts" />
+
+export namespace form {
+  export const input = null;
+
+  export const HiddenInput = () => null;
+
+  export const test1 = <input />;
+  export const test2 = <HiddenInput />;
+}
+
+
+//// [namespaceJsxPreserve1.jsx]
+"use strict";
+/// <reference path="react16.d.ts" />
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.form = void 0;
+var form;
+(function (form) {
+    form.input = null;
+    form.HiddenInput = function () { return null; };
+    form.test1 = <input />;
+    form.test2 = <form.HiddenInput />;
+})(form || (exports.form = form = {}));

tests/baselines/reference/namespaceJsxPreserve1.symbols

@@ -0,0 +1,23 @@
+//// [tests/cases/compiler/namespaceJsxPreserve1.tsx] ////
+
+=== namespaceJsxPreserve1.tsx ===
+/// <reference path="react16.d.ts" />
+
+export namespace form {
+>form : Symbol(form, Decl(namespaceJsxPreserve1.tsx, 0, 0))
+
+  export const input = null;
+>input : Symbol(input, Decl(namespaceJsxPreserve1.tsx, 3, 14))
+
+  export const HiddenInput = () => null;
+>HiddenInput : Symbol(HiddenInput, Decl(namespaceJsxPreserve1.tsx, 5, 14))
+
+  export const test1 = <input />;
+>test1 : Symbol(test1, Decl(namespaceJsxPreserve1.tsx, 7, 14))
+>input : Symbol(JSX.IntrinsicElements.input, Decl(react16.d.ts, 2570, 106))
+
+  export const test2 = <HiddenInput />;
+>test2 : Symbol(test2, Decl(namespaceJsxPreserve1.tsx, 8, 14))
+>HiddenInput : Symbol(HiddenInput, Decl(namespaceJsxPreserve1.tsx, 5, 14))
+}
+

tests/baselines/reference/namespaceJsxPreserve1.types

@@ -0,0 +1,42 @@
+//// [tests/cases/compiler/namespaceJsxPreserve1.tsx] ////
+
+=== Performance Stats ===
+Assignability cache: 2,500
+Type Count: 10,000
+Instantiation count: 100,000
+Symbol count: 50,000
+
+=== namespaceJsxPreserve1.tsx ===
+/// <reference path="react16.d.ts" />
+
+export namespace form {
+>form : typeof form
+>     : ^^^^^^^^^^^
+
+  export const input = null;
+>input : null
+>      : ^^^^
+
+  export const HiddenInput = () => null;
+>HiddenInput : () => null
+>            : ^^^^^^^^^^
+>() => null : () => null
+>           : ^^^^^^^^^^
+
+  export const test1 = <input />;
+>test1 : JSX.Element
+>      : ^^^^^^^^^^^
+><input /> : JSX.Element
+>          : ^^^^^^^^^^^
+>input : null
+>      : ^^^^
+
+  export const test2 = <HiddenInput />;
+>test2 : JSX.Element
+>      : ^^^^^^^^^^^
+><HiddenInput /> : JSX.Element
+>                : ^^^^^^^^^^^
+>HiddenInput : () => null
+>            : ^^^^^^^^^^
+}
+

tests/cases/compiler/namespaceJsxPreserve1.tsx

@@ -0,0 +1,13 @@
+// @strict: true
+// @jsx: preserve
+
+/// <reference path="/.lib/react16.d.ts" />
+
+export namespace form {
+  export const input = null;
+
+  export const HiddenInput = () => null;
+
+  export const test1 = <input />;
+  export const test2 = <HiddenInput />;
+}