Grammar error on export type * (#37064)

* Recognize `export type *` syntax, but disallow it

* Add more comments to test

* Revert recognizing invalid forms as type-only

* Revert more

src/compiler/checker.ts

@@ -1936,10 +1936,11 @@ namespace ts {
             if (!isValidTypeOnlyAliasUseSite(useSite)) {
                 const typeOnlyDeclaration = getTypeOnlyAliasDeclaration(symbol);
                 if (typeOnlyDeclaration) {
-                    const message = typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier
+                    const isExport = typeOnlyDeclarationIsExport(typeOnlyDeclaration);
+                    const message = isExport
                         ? Diagnostics._0_cannot_be_used_as_a_value_because_it_was_exported_using_export_type
                         : Diagnostics._0_cannot_be_used_as_a_value_because_it_was_imported_using_import_type;
-                    const relatedMessage = typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier
+                    const relatedMessage = isExport
                         ? Diagnostics._0_was_exported_here
                         : Diagnostics._0_was_imported_here;
                     const unescapedName = unescapeLeadingUnderscores(name);
@@ -2286,12 +2287,14 @@ namespace ts {
         function checkAndReportErrorForResolvingImportAliasToTypeOnlySymbol(node: ImportEqualsDeclaration, resolved: Symbol | undefined) {
             if (markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false)) {
                 const typeOnlyDeclaration = getTypeOnlyAliasDeclaration(getSymbolOfNode(node))!;
-                const message = typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier
+                const isExport = typeOnlyDeclarationIsExport(typeOnlyDeclaration);
+                const message = isExport
                     ? Diagnostics.An_import_alias_cannot_reference_a_declaration_that_was_exported_using_export_type
                     : Diagnostics.An_import_alias_cannot_reference_a_declaration_that_was_imported_using_import_type;
-                const relatedMessage = typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier
+                const relatedMessage = isExport
                     ? Diagnostics._0_was_exported_here
                     : Diagnostics._0_was_imported_here;
+
                 // Non-null assertion is safe because the optionality comes from ImportClause,
                 // but if an ImportClause was the typeOnlyDeclaration, it had to have a `name`.
                 const name = unescapeLeadingUnderscores(typeOnlyDeclaration.name!.escapedText);
@@ -33598,6 +33601,7 @@ namespace ts {
                 checkExternalEmitHelpers(node, ExternalEmitHelpers.CreateBinding);
             }
 
+            checkGrammarExportDeclaration(node);
             if (!node.moduleSpecifier || checkExternalImportOrExportDeclaration(node)) {
                 if (node.exportClause) {
                     // export { x, y }
@@ -33630,6 +33634,14 @@ namespace ts {
             }
         }
 
+        function checkGrammarExportDeclaration(node: ExportDeclaration): boolean {
+            const isTypeOnlyExportStar = node.isTypeOnly && node.exportClause?.kind !== SyntaxKind.NamedExports;
+            if (isTypeOnlyExportStar) {
+                grammarErrorOnNode(node, Diagnostics.Only_named_exports_may_use_export_type);
+            }
+            return !isTypeOnlyExportStar;
+        }
+
         function checkGrammarModuleElementContext(node: Statement, errorMessage: DiagnosticMessage): boolean {
             const isInAppropriateContext = node.parent.kind === SyntaxKind.SourceFile || node.parent.kind === SyntaxKind.ModuleBlock || node.parent.kind === SyntaxKind.ModuleDeclaration;
             if (!isInAppropriateContext) {

src/compiler/diagnosticMessages.json

@@ -1143,6 +1143,10 @@
         "category": "Error",
         "code": 1382
     },
+    "Only named exports may use 'export type'.": {
+        "category": "Error",
+        "code": 1383
+    },
 
     "The types of '{0}' are incompatible between these types.": {
         "category": "Error",

src/compiler/utilities.ts

@@ -6220,6 +6220,10 @@ namespace ts {
             || !isExpressionNode(useSite);
     }
 
+    export function typeOnlyDeclarationIsExport(typeOnlyDeclaration: Node) {
+        return typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier;
+    }
+
     function isPartOfPossiblyValidTypeOrAbstractComputedPropertyName(node: Node) {
         while (node.kind === SyntaxKind.Identifier || node.kind === SyntaxKind.PropertyAccessExpression) {
             node = node.parent;

tests/baselines/reference/exportNamespace4.errors.txt

@@ -0,0 +1,25 @@
+tests/cases/conformance/externalModules/typeOnly/b.ts(1,1): error TS1383: Only named exports may use 'export type'.
+tests/cases/conformance/externalModules/typeOnly/c.ts(1,1): error TS1383: Only named exports may use 'export type'.
+
+
+==== tests/cases/conformance/externalModules/typeOnly/a.ts (0 errors) ====
+    export class A {}
+
+==== tests/cases/conformance/externalModules/typeOnly/b.ts (1 errors) ====
+    export type * from './a'; // Grammar error
+    ~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1383: Only named exports may use 'export type'.
+
+==== tests/cases/conformance/externalModules/typeOnly/c.ts (1 errors) ====
+    export type * as ns from './a'; // Grammar error
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1383: Only named exports may use 'export type'.
+
+==== tests/cases/conformance/externalModules/typeOnly/d.ts (0 errors) ====
+    import { A } from './b';
+    A;
+
+==== tests/cases/conformance/externalModules/typeOnly/e.ts (0 errors) ====
+    import { ns } from './c';
+    ns.A;
+

tests/baselines/reference/exportNamespace4.js

@@ -0,0 +1,45 @@
+//// [tests/cases/conformance/externalModules/typeOnly/exportNamespace4.ts] ////
+
+//// [a.ts]
+export class A {}
+
+//// [b.ts]
+export type * from './a'; // Grammar error
+
+//// [c.ts]
+export type * as ns from './a'; // Grammar error
+
+//// [d.ts]
+import { A } from './b';
+A;
+
+//// [e.ts]
+import { ns } from './c';
+ns.A;
+
+
+//// [a.js]
+"use strict";
+exports.__esModule = true;
+var A = /** @class */ (function () {
+    function A() {
+    }
+    return A;
+}());
+exports.A = A;
+//// [b.js]
+"use strict";
+exports.__esModule = true;
+//// [c.js]
+"use strict";
+exports.__esModule = true;
+//// [d.js]
+"use strict";
+exports.__esModule = true;
+var b_1 = require("./b");
+b_1.A;
+//// [e.js]
+"use strict";
+exports.__esModule = true;
+var c_1 = require("./c");
+c_1.ns.A;

tests/baselines/reference/exportNamespace4.symbols

@@ -0,0 +1,27 @@
+=== tests/cases/conformance/externalModules/typeOnly/a.ts ===
+export class A {}
+>A : Symbol(A, Decl(a.ts, 0, 0))
+
+=== tests/cases/conformance/externalModules/typeOnly/b.ts ===
+export type * from './a'; // Grammar error
+No type information for this code.
+No type information for this code.=== tests/cases/conformance/externalModules/typeOnly/c.ts ===
+export type * as ns from './a'; // Grammar error
+>ns : Symbol(ns, Decl(c.ts, 0, 11))
+
+=== tests/cases/conformance/externalModules/typeOnly/d.ts ===
+import { A } from './b';
+>A : Symbol(A, Decl(d.ts, 0, 8))
+
+A;
+>A : Symbol(A, Decl(d.ts, 0, 8))
+
+=== tests/cases/conformance/externalModules/typeOnly/e.ts ===
+import { ns } from './c';
+>ns : Symbol(ns, Decl(e.ts, 0, 8))
+
+ns.A;
+>ns.A : Symbol(ns.A, Decl(a.ts, 0, 0))
+>ns : Symbol(ns, Decl(e.ts, 0, 8))
+>A : Symbol(ns.A, Decl(a.ts, 0, 0))
+

tests/baselines/reference/exportNamespace4.types

@@ -0,0 +1,27 @@
+=== tests/cases/conformance/externalModules/typeOnly/a.ts ===
+export class A {}
+>A : A
+
+=== tests/cases/conformance/externalModules/typeOnly/b.ts ===
+export type * from './a'; // Grammar error
+No type information for this code.
+No type information for this code.=== tests/cases/conformance/externalModules/typeOnly/c.ts ===
+export type * as ns from './a'; // Grammar error
+>ns : typeof ns
+
+=== tests/cases/conformance/externalModules/typeOnly/d.ts ===
+import { A } from './b';
+>A : typeof A
+
+A;
+>A : typeof A
+
+=== tests/cases/conformance/externalModules/typeOnly/e.ts ===
+import { ns } from './c';
+>ns : typeof ns
+
+ns.A;
+>ns.A : typeof ns.A
+>ns : typeof ns
+>A : typeof ns.A
+

tests/cases/conformance/externalModules/typeOnly/exportNamespace4.ts

@@ -0,0 +1,16 @@
+// @Filename: a.ts
+export class A {}
+
+// @Filename: b.ts
+export type * from './a'; // Grammar error
+
+// @Filename: c.ts
+export type * as ns from './a'; // Grammar error
+
+// @Filename: d.ts
+import { A } from './b';
+A;
+
+// @Filename: e.ts
+import { ns } from './c';
+ns.A;