Add missing isolatedModules error for export import

src/compiler/checker.ts

@@ -39940,6 +39940,9 @@ namespace ts {
                                         name
                                     );
                                 }
+                                if (isType && node.kind === SyntaxKind.ImportEqualsDeclaration && hasEffectiveModifier(node, ModifierFlags.Export)) {
+                                    error(node, Diagnostics.Cannot_use_export_import_on_a_type_or_type_only_namespace_when_the_isolatedModules_flag_is_provided);
+                                }
                                 break;
                             }
                             case SyntaxKind.ExportSpecifier: {

src/compiler/diagnosticMessages.json

@@ -867,6 +867,10 @@
         "category": "Error",
         "code": 1268
     },
+    "Cannot use 'export import' on a type or type-only namespace when the '--isolatedModules' flag is provided.": {
+        "category": "Error",
+        "code": 1269
+    },
 
     "'with' statements are not allowed in an async function block.": {
         "category": "Error",
@@ -1421,7 +1425,7 @@
         "category": "Error",
         "code": 1474
     },
-    
+
     "The types of '{0}' are incompatible between these types.": {
         "category": "Error",
         "code": 2200

tests/baselines/reference/isolatedModulesExportImportUninstantiatedNamespace.errors.txt

@@ -0,0 +1,25 @@
+tests/cases/compiler/factory.ts(3,1): error TS1269: Cannot use 'export import' on a type or type-only namespace when the '--isolatedModules' flag is provided.
+
+
+==== tests/cases/compiler/jsx.ts (0 errors) ====
+    export namespace JSXInternal {
+      export type HTMLAttributes = string
+      export type ComponentChildren = string
+    }
+
+==== tests/cases/compiler/factory.ts (1 errors) ====
+    import { JSXInternal } from "./jsx"
+
+    export import JSX = JSXInternal;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1269: Cannot use 'export import' on a type or type-only namespace when the '--isolatedModules' flag is provided.
+
+    export function createElement<ElementType extends HTMLElement>(
+      tagName: string,
+      attributes: JSX.HTMLAttributes,
+      ...children: JSX.ComponentChildren[]
+    ): any {
+      //...
+    }
+
+

tests/baselines/reference/isolatedModulesExportImportUninstantiatedNamespace.js

@@ -0,0 +1,33 @@
+//// [tests/cases/compiler/isolatedModulesExportImportUninstantiatedNamespace.ts] ////
+
+//// [jsx.ts]
+export namespace JSXInternal {
+  export type HTMLAttributes = string
+  export type ComponentChildren = string
+}
+
+//// [factory.ts]
+import { JSXInternal } from "./jsx"
+
+export import JSX = JSXInternal;
+
+export function createElement<ElementType extends HTMLElement>(
+  tagName: string,
+  attributes: JSX.HTMLAttributes,
+  ...children: JSX.ComponentChildren[]
+): any {
+  //...
+}
+
+
+
+//// [jsx.js]
+export {};
+//// [factory.js]
+export function createElement(tagName, attributes) {
+    var children = [];
+    for (var _i = 2; _i < arguments.length; _i++) {
+        children[_i - 2] = arguments[_i];
+    }
+    //...
+}

tests/baselines/reference/isolatedModulesReExportType.errors.txt

@@ -1,14 +1,17 @@
 /user.ts(2,10): error TS1205: Re-exporting a type when the '--isolatedModules' flag is provided requires using 'export type'.
+/user.ts(3,1): error TS1269: Cannot use 'export import' on a type or type-only namespace when the '--isolatedModules' flag is provided.
 /user.ts(17,10): error TS1205: Re-exporting a type when the '--isolatedModules' flag is provided requires using 'export type'.
 /user.ts(25,10): error TS1448: 'CC' resolves to a type-only declaration and must be re-exported using a type-only re-export when 'isolatedModules' is enabled.
 
 
-==== /user.ts (3 errors) ====
+==== /user.ts (4 errors) ====
     // Error, can't re-export something that's only a type.
     export { T } from "./exportT";
              ~
 !!! error TS1205: Re-exporting a type when the '--isolatedModules' flag is provided requires using 'export type'.
     export import T2 = require("./exportEqualsT");
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1269: Cannot use 'export import' on a type or type-only namespace when the '--isolatedModules' flag is provided.
 
     // OK, has a value side
     export { C } from "./exportValue";

tests/cases/compiler/isolatedModulesExportImportUninstantiatedNamespace.ts

@@ -0,0 +1,23 @@
+// @module: esnext
+// @isolatedModules: true
+// @noTypesAndSymbols: true
+
+// @Filename: jsx.ts
+export namespace JSXInternal {
+  export type HTMLAttributes = string
+  export type ComponentChildren = string
+}
+
+// @Filename: factory.ts
+import { JSXInternal } from "./jsx"
+
+export import JSX = JSXInternal;
+
+export function createElement<ElementType extends HTMLElement>(
+  tagName: string,
+  attributes: JSX.HTMLAttributes,
+  ...children: JSX.ComponentChildren[]
+): any {
+  //...
+}
+