From e36096544777feef142602a72dd22fb4f01b7449 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Wed, 26 Feb 2020 16:36:00 -0800
Subject: [PATCH 1/4] Recognize `export type *` syntax, but disallow it

---
 src/compiler/checker.ts                       | 38 ++++++++++++----
 src/compiler/diagnosticMessages.json          |  4 ++
 src/compiler/utilities.ts                     |  5 +++
 src/compiler/utilitiesPublic.ts               |  6 ++-
 .../reference/exportNamespace4.errors.txt     | 33 ++++++++++++++
 tests/baselines/reference/exportNamespace4.js | 43 +++++++++++++++++++
 .../reference/exportNamespace4.symbols        | 27 ++++++++++++
 .../reference/exportNamespace4.types          | 27 ++++++++++++
 .../typeOnly/exportNamespace4.ts              | 16 +++++++
 9 files changed, 188 insertions(+), 11 deletions(-)
 create mode 100644 tests/baselines/reference/exportNamespace4.errors.txt
 create mode 100644 tests/baselines/reference/exportNamespace4.js
 create mode 100644 tests/baselines/reference/exportNamespace4.symbols
 create mode 100644 tests/baselines/reference/exportNamespace4.types
 create mode 100644 tests/cases/conformance/externalModules/typeOnly/exportNamespace4.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 34e8a6336ae3c..51af91142446c 100644
--- a/src/compiler/checker.ts
+++ b/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);
@@ -2286,15 +2287,19 @@ 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);
+
+                // Non-null assertion is safe because `markSymbolOfAliasDeclarationIfTypeOnly` cannot return true
+                // for an ImportEqualsDeclaration without also being passed a defined symbol.
+                // `typeOnlyDeclaration.name` will be an Identifier for all valid cases, but may be undefined for
+                // invalid `export type * ...` syntax.
+                const name = unescapeLeadingUnderscores(tryCast(typeOnlyDeclaration.name, isIdentifier)?.escapedText ?? resolved!.escapedName);
                 addRelatedInfo(error(node.moduleReference, message), createDiagnosticForNode(typeOnlyDeclaration, relatedMessage, name));
             }
         }
@@ -2452,7 +2457,12 @@ namespace ts {
                 const name = (specifier.propertyName ?? specifier.name).escapedText;
                 const exportSymbol = getExportsOfSymbol(symbol).get(name);
                 const resolved = resolveSymbol(exportSymbol, dontResolveAlias);
-                markSymbolOfAliasDeclarationIfTypeOnly(specifier, exportSymbol, resolved, /*overwriteEmpty*/ false);
+                if (!markSymbolOfAliasDeclarationIfTypeOnly(specifier, exportSymbol, resolved, /*overwriteEmpty*/ false)) {
+                    if (resolved && symbol.exports && !symbol.exports.has(name)) {
+                        // `resolved` must have come from a namespace export, which could be `export type *`
+                        markSymbolOfAliasDeclarationIfTypeOnly(specifier, symbol.exports.get(InternalSymbolName.ExportStar), /*finalTarget*/ undefined, /*overwriteEmpty*/ true);
+                    }
+                }
                 return resolved;
             }
         }
@@ -2725,7 +2735,7 @@ namespace ts {
         }
 
         /** Indicates that a symbol directly or indirectly resolves to a type-only import or export. */
-        function getTypeOnlyAliasDeclaration(symbol: Symbol): TypeOnlyCompatibleAliasDeclaration | undefined {
+        function getTypeOnlyAliasDeclaration(symbol: Symbol): TypeOnlyCompatibleAliasDeclaration | NamespaceExport | ExportDeclaration | undefined {
             if (!(symbol.flags & SymbolFlags.Alias)) {
                 return undefined;
             }
@@ -3262,6 +3272,7 @@ namespace ts {
                     const lookupTable = createMap<ExportCollisionTracker>() as ExportCollisionTrackerTable;
                     for (const node of exportStars.declarations) {
                         const resolvedModule = resolveExternalModuleName(node, (node as ExportDeclaration).moduleSpecifier!);
+                        markSymbolOfAliasDeclarationIfTypeOnly(node, resolvedModule, /*finalTarget*/ undefined, /*overwriteEmpty*/ false);
                         const exportedSymbols = visit(resolvedModule);
                         extendExportSymbols(
                             nestedSymbols,
@@ -33537,6 +33548,7 @@ namespace ts {
                 checkExternalEmitHelpers(node, ExternalEmitHelpers.CreateBinding);
             }
 
+            checkGrammarExportDeclaration(node);
             if (!node.moduleSpecifier || checkExternalImportOrExportDeclaration(node)) {
                 if (node.exportClause) {
                     // export { x, y }
@@ -33569,6 +33581,14 @@ 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) {
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 4ee407ce1c1e9..b58c0cd92783c 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/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",
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index 7badd3af99e39..fc72453565194 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -6215,6 +6215,11 @@ namespace ts {
             || !isExpressionNode(useSite);
     }
 
+    export function typeOnlyDeclarationIsExport(typeOnlyDeclaration: Node) {
+        const kind = typeOnlyDeclaration.kind;
+        return kind === SyntaxKind.ExportSpecifier || kind === SyntaxKind.NamespaceExport || kind === SyntaxKind.ExportDeclaration;
+    }
+
     function isPartOfPossiblyValidTypeOrAbstractComputedPropertyName(node: Node) {
         while (node.kind === SyntaxKind.Identifier || node.kind === SyntaxKind.PropertyAccessExpression) {
             node = node.parent;
diff --git a/src/compiler/utilitiesPublic.ts b/src/compiler/utilitiesPublic.ts
index 052144fdc001f..8fd8426980458 100644
--- a/src/compiler/utilitiesPublic.ts
+++ b/src/compiler/utilitiesPublic.ts
@@ -1727,9 +1727,11 @@ namespace ts {
             case SyntaxKind.ExportSpecifier:
                 return (node as ImportOrExportSpecifier).parent.parent.isTypeOnly;
             case SyntaxKind.NamespaceImport:
-                return (node as NamespaceImport).parent.isTypeOnly;
+            case SyntaxKind.NamespaceExport:
+                return (node as NamespaceImport | NamespaceExport).parent.isTypeOnly;
             case SyntaxKind.ImportClause:
-                return (node as ImportClause).isTypeOnly;
+            case SyntaxKind.ExportDeclaration:
+                return (node as ImportClause | ExportDeclaration).isTypeOnly;
             default:
                 return false;
         }
diff --git a/tests/baselines/reference/exportNamespace4.errors.txt b/tests/baselines/reference/exportNamespace4.errors.txt
new file mode 100644
index 0000000000000..36c1a5d24eb86
--- /dev/null
+++ b/tests/baselines/reference/exportNamespace4.errors.txt
@@ -0,0 +1,33 @@
+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/d.ts(2,1): error TS1362: 'A' cannot be used as a value because it was exported using 'export type'.
+tests/cases/conformance/externalModules/typeOnly/e.ts(2,1): error TS1362: 'ns' cannot be used as a value because it was exported using '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';
+    ~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1383: Only named exports may use 'export type'.
+    
+==== tests/cases/conformance/externalModules/typeOnly/c.ts (1 errors) ====
+    export type * as ns from './a';
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1383: Only named exports may use 'export type'.
+    
+==== tests/cases/conformance/externalModules/typeOnly/d.ts (1 errors) ====
+    import { A } from './b';
+    A; // Error
+    ~
+!!! error TS1362: 'A' cannot be used as a value because it was exported using 'export type'.
+!!! related TS1377 tests/cases/conformance/externalModules/typeOnly/b.ts:1:1: 'A' was exported here.
+    
+==== tests/cases/conformance/externalModules/typeOnly/e.ts (1 errors) ====
+    import { ns } from './c';
+    ns.A; // Error
+    ~~
+!!! error TS1362: 'ns' cannot be used as a value because it was exported using 'export type'.
+!!! related TS1377 tests/cases/conformance/externalModules/typeOnly/c.ts:1:13: 'ns' was exported here.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/exportNamespace4.js b/tests/baselines/reference/exportNamespace4.js
new file mode 100644
index 0000000000000..e575549156ab9
--- /dev/null
+++ b/tests/baselines/reference/exportNamespace4.js
@@ -0,0 +1,43 @@
+//// [tests/cases/conformance/externalModules/typeOnly/exportNamespace4.ts] ////
+
+//// [a.ts]
+export class A {}
+
+//// [b.ts]
+export type * from './a';
+
+//// [c.ts]
+export type * as ns from './a';
+
+//// [d.ts]
+import { A } from './b';
+A; // Error
+
+//// [e.ts]
+import { ns } from './c';
+ns.A; // Error
+
+
+//// [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;
+A; // Error
+//// [e.js]
+"use strict";
+exports.__esModule = true;
+ns.A; // Error
diff --git a/tests/baselines/reference/exportNamespace4.symbols b/tests/baselines/reference/exportNamespace4.symbols
new file mode 100644
index 0000000000000..5ba8df1390e5a
--- /dev/null
+++ b/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';
+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';
+>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; // Error
+>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; // Error
+>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))
+
diff --git a/tests/baselines/reference/exportNamespace4.types b/tests/baselines/reference/exportNamespace4.types
new file mode 100644
index 0000000000000..2e3ead71d0fc3
--- /dev/null
+++ b/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';
+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';
+>ns : typeof ns
+
+=== tests/cases/conformance/externalModules/typeOnly/d.ts ===
+import { A } from './b';
+>A : typeof A
+
+A; // Error
+>A : typeof A
+
+=== tests/cases/conformance/externalModules/typeOnly/e.ts ===
+import { ns } from './c';
+>ns : typeof ns
+
+ns.A; // Error
+>ns.A : typeof ns.A
+>ns : typeof ns
+>A : typeof ns.A
+
diff --git a/tests/cases/conformance/externalModules/typeOnly/exportNamespace4.ts b/tests/cases/conformance/externalModules/typeOnly/exportNamespace4.ts
new file mode 100644
index 0000000000000..5a6b7f6835c5c
--- /dev/null
+++ b/tests/cases/conformance/externalModules/typeOnly/exportNamespace4.ts
@@ -0,0 +1,16 @@
+// @Filename: a.ts
+export class A {}
+
+// @Filename: b.ts
+export type * from './a';
+
+// @Filename: c.ts
+export type * as ns from './a';
+
+// @Filename: d.ts
+import { A } from './b';
+A; // Error
+
+// @Filename: e.ts
+import { ns } from './c';
+ns.A; // Error

From 7615d29b00d80d03af934689918c8b3c6f3d2547 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Wed, 26 Feb 2020 16:39:33 -0800
Subject: [PATCH 2/4] Add more comments to test

---
 tests/baselines/reference/exportNamespace4.errors.txt         | 4 ++--
 tests/baselines/reference/exportNamespace4.js                 | 4 ++--
 tests/baselines/reference/exportNamespace4.symbols            | 4 ++--
 tests/baselines/reference/exportNamespace4.types              | 4 ++--
 .../conformance/externalModules/typeOnly/exportNamespace4.ts  | 4 ++--
 5 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/tests/baselines/reference/exportNamespace4.errors.txt b/tests/baselines/reference/exportNamespace4.errors.txt
index 36c1a5d24eb86..706d5b14d698b 100644
--- a/tests/baselines/reference/exportNamespace4.errors.txt
+++ b/tests/baselines/reference/exportNamespace4.errors.txt
@@ -8,12 +8,12 @@ tests/cases/conformance/externalModules/typeOnly/e.ts(2,1): error TS1362: 'ns' c
     export class A {}
     
 ==== tests/cases/conformance/externalModules/typeOnly/b.ts (1 errors) ====
-    export type * from './a';
+    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';
+    export type * as ns from './a'; // Grammar error
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS1383: Only named exports may use 'export type'.
     
diff --git a/tests/baselines/reference/exportNamespace4.js b/tests/baselines/reference/exportNamespace4.js
index e575549156ab9..d17adcc51176a 100644
--- a/tests/baselines/reference/exportNamespace4.js
+++ b/tests/baselines/reference/exportNamespace4.js
@@ -4,10 +4,10 @@
 export class A {}
 
 //// [b.ts]
-export type * from './a';
+export type * from './a'; // Grammar error
 
 //// [c.ts]
-export type * as ns from './a';
+export type * as ns from './a'; // Grammar error
 
 //// [d.ts]
 import { A } from './b';
diff --git a/tests/baselines/reference/exportNamespace4.symbols b/tests/baselines/reference/exportNamespace4.symbols
index 5ba8df1390e5a..c93887db8aa5a 100644
--- a/tests/baselines/reference/exportNamespace4.symbols
+++ b/tests/baselines/reference/exportNamespace4.symbols
@@ -3,10 +3,10 @@ export class A {}
 >A : Symbol(A, Decl(a.ts, 0, 0))
 
 === tests/cases/conformance/externalModules/typeOnly/b.ts ===
-export type * from './a';
+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';
+export type * as ns from './a'; // Grammar error
 >ns : Symbol(ns, Decl(c.ts, 0, 11))
 
 === tests/cases/conformance/externalModules/typeOnly/d.ts ===
diff --git a/tests/baselines/reference/exportNamespace4.types b/tests/baselines/reference/exportNamespace4.types
index 2e3ead71d0fc3..897dd4cc3c796 100644
--- a/tests/baselines/reference/exportNamespace4.types
+++ b/tests/baselines/reference/exportNamespace4.types
@@ -3,10 +3,10 @@ export class A {}
 >A : A
 
 === tests/cases/conformance/externalModules/typeOnly/b.ts ===
-export type * from './a';
+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';
+export type * as ns from './a'; // Grammar error
 >ns : typeof ns
 
 === tests/cases/conformance/externalModules/typeOnly/d.ts ===
diff --git a/tests/cases/conformance/externalModules/typeOnly/exportNamespace4.ts b/tests/cases/conformance/externalModules/typeOnly/exportNamespace4.ts
index 5a6b7f6835c5c..3f708ce0d54e2 100644
--- a/tests/cases/conformance/externalModules/typeOnly/exportNamespace4.ts
+++ b/tests/cases/conformance/externalModules/typeOnly/exportNamespace4.ts
@@ -2,10 +2,10 @@
 export class A {}
 
 // @Filename: b.ts
-export type * from './a';
+export type * from './a'; // Grammar error
 
 // @Filename: c.ts
-export type * as ns from './a';
+export type * as ns from './a'; // Grammar error
 
 // @Filename: d.ts
 import { A } from './b';

From 81f62824dda055f52a38fd254112ae6b54128d31 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Thu, 27 Feb 2020 11:32:07 -0800
Subject: [PATCH 3/4] Revert recognizing invalid forms as type-only

---
 src/compiler/checker.ts                          |  8 +-------
 src/compiler/utilitiesPublic.ts                  |  6 ++----
 .../reference/exportNamespace4.errors.txt        | 16 ++++------------
 tests/baselines/reference/exportNamespace4.js    | 10 ++++++----
 .../baselines/reference/exportNamespace4.symbols |  4 ++--
 tests/baselines/reference/exportNamespace4.types |  4 ++--
 .../externalModules/typeOnly/exportNamespace4.ts |  4 ++--
 7 files changed, 19 insertions(+), 33 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 51af91142446c..514b5af7d2fea 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -2457,12 +2457,7 @@ namespace ts {
                 const name = (specifier.propertyName ?? specifier.name).escapedText;
                 const exportSymbol = getExportsOfSymbol(symbol).get(name);
                 const resolved = resolveSymbol(exportSymbol, dontResolveAlias);
-                if (!markSymbolOfAliasDeclarationIfTypeOnly(specifier, exportSymbol, resolved, /*overwriteEmpty*/ false)) {
-                    if (resolved && symbol.exports && !symbol.exports.has(name)) {
-                        // `resolved` must have come from a namespace export, which could be `export type *`
-                        markSymbolOfAliasDeclarationIfTypeOnly(specifier, symbol.exports.get(InternalSymbolName.ExportStar), /*finalTarget*/ undefined, /*overwriteEmpty*/ true);
-                    }
-                }
+                markSymbolOfAliasDeclarationIfTypeOnly(specifier, exportSymbol, resolved, /*overwriteEmpty*/ false);
                 return resolved;
             }
         }
@@ -3272,7 +3267,6 @@ namespace ts {
                     const lookupTable = createMap<ExportCollisionTracker>() as ExportCollisionTrackerTable;
                     for (const node of exportStars.declarations) {
                         const resolvedModule = resolveExternalModuleName(node, (node as ExportDeclaration).moduleSpecifier!);
-                        markSymbolOfAliasDeclarationIfTypeOnly(node, resolvedModule, /*finalTarget*/ undefined, /*overwriteEmpty*/ false);
                         const exportedSymbols = visit(resolvedModule);
                         extendExportSymbols(
                             nestedSymbols,
diff --git a/src/compiler/utilitiesPublic.ts b/src/compiler/utilitiesPublic.ts
index 8fd8426980458..052144fdc001f 100644
--- a/src/compiler/utilitiesPublic.ts
+++ b/src/compiler/utilitiesPublic.ts
@@ -1727,11 +1727,9 @@ namespace ts {
             case SyntaxKind.ExportSpecifier:
                 return (node as ImportOrExportSpecifier).parent.parent.isTypeOnly;
             case SyntaxKind.NamespaceImport:
-            case SyntaxKind.NamespaceExport:
-                return (node as NamespaceImport | NamespaceExport).parent.isTypeOnly;
+                return (node as NamespaceImport).parent.isTypeOnly;
             case SyntaxKind.ImportClause:
-            case SyntaxKind.ExportDeclaration:
-                return (node as ImportClause | ExportDeclaration).isTypeOnly;
+                return (node as ImportClause).isTypeOnly;
             default:
                 return false;
         }
diff --git a/tests/baselines/reference/exportNamespace4.errors.txt b/tests/baselines/reference/exportNamespace4.errors.txt
index 706d5b14d698b..30b849456e67f 100644
--- a/tests/baselines/reference/exportNamespace4.errors.txt
+++ b/tests/baselines/reference/exportNamespace4.errors.txt
@@ -1,7 +1,5 @@
 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/d.ts(2,1): error TS1362: 'A' cannot be used as a value because it was exported using 'export type'.
-tests/cases/conformance/externalModules/typeOnly/e.ts(2,1): error TS1362: 'ns' cannot be used as a value because it was exported using 'export type'.
 
 
 ==== tests/cases/conformance/externalModules/typeOnly/a.ts (0 errors) ====
@@ -17,17 +15,11 @@ tests/cases/conformance/externalModules/typeOnly/e.ts(2,1): error TS1362: 'ns' c
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS1383: Only named exports may use 'export type'.
     
-==== tests/cases/conformance/externalModules/typeOnly/d.ts (1 errors) ====
+==== tests/cases/conformance/externalModules/typeOnly/d.ts (0 errors) ====
     import { A } from './b';
-    A; // Error
-    ~
-!!! error TS1362: 'A' cannot be used as a value because it was exported using 'export type'.
-!!! related TS1377 tests/cases/conformance/externalModules/typeOnly/b.ts:1:1: 'A' was exported here.
+    A;
     
-==== tests/cases/conformance/externalModules/typeOnly/e.ts (1 errors) ====
+==== tests/cases/conformance/externalModules/typeOnly/e.ts (0 errors) ====
     import { ns } from './c';
-    ns.A; // Error
-    ~~
-!!! error TS1362: 'ns' cannot be used as a value because it was exported using 'export type'.
-!!! related TS1377 tests/cases/conformance/externalModules/typeOnly/c.ts:1:13: 'ns' was exported here.
+    ns.A;
     
\ No newline at end of file
diff --git a/tests/baselines/reference/exportNamespace4.js b/tests/baselines/reference/exportNamespace4.js
index d17adcc51176a..e7da4ca86d055 100644
--- a/tests/baselines/reference/exportNamespace4.js
+++ b/tests/baselines/reference/exportNamespace4.js
@@ -11,11 +11,11 @@ export type * as ns from './a'; // Grammar error
 
 //// [d.ts]
 import { A } from './b';
-A; // Error
+A;
 
 //// [e.ts]
 import { ns } from './c';
-ns.A; // Error
+ns.A;
 
 
 //// [a.js]
@@ -36,8 +36,10 @@ exports.__esModule = true;
 //// [d.js]
 "use strict";
 exports.__esModule = true;
-A; // Error
+var b_1 = require("./b");
+b_1.A;
 //// [e.js]
 "use strict";
 exports.__esModule = true;
-ns.A; // Error
+var c_1 = require("./c");
+c_1.ns.A;
diff --git a/tests/baselines/reference/exportNamespace4.symbols b/tests/baselines/reference/exportNamespace4.symbols
index c93887db8aa5a..860bb80b87795 100644
--- a/tests/baselines/reference/exportNamespace4.symbols
+++ b/tests/baselines/reference/exportNamespace4.symbols
@@ -13,14 +13,14 @@ export type * as ns from './a'; // Grammar error
 import { A } from './b';
 >A : Symbol(A, Decl(d.ts, 0, 8))
 
-A; // Error
+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; // Error
+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))
diff --git a/tests/baselines/reference/exportNamespace4.types b/tests/baselines/reference/exportNamespace4.types
index 897dd4cc3c796..18155fb4eb6e8 100644
--- a/tests/baselines/reference/exportNamespace4.types
+++ b/tests/baselines/reference/exportNamespace4.types
@@ -13,14 +13,14 @@ export type * as ns from './a'; // Grammar error
 import { A } from './b';
 >A : typeof A
 
-A; // Error
+A;
 >A : typeof A
 
 === tests/cases/conformance/externalModules/typeOnly/e.ts ===
 import { ns } from './c';
 >ns : typeof ns
 
-ns.A; // Error
+ns.A;
 >ns.A : typeof ns.A
 >ns : typeof ns
 >A : typeof ns.A
diff --git a/tests/cases/conformance/externalModules/typeOnly/exportNamespace4.ts b/tests/cases/conformance/externalModules/typeOnly/exportNamespace4.ts
index 3f708ce0d54e2..889552e6643fe 100644
--- a/tests/cases/conformance/externalModules/typeOnly/exportNamespace4.ts
+++ b/tests/cases/conformance/externalModules/typeOnly/exportNamespace4.ts
@@ -9,8 +9,8 @@ export type * as ns from './a'; // Grammar error
 
 // @Filename: d.ts
 import { A } from './b';
-A; // Error
+A;
 
 // @Filename: e.ts
 import { ns } from './c';
-ns.A; // Error
+ns.A;

From 0c7831d66098289bcaf320485383475b03c56643 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Thu, 27 Feb 2020 11:36:18 -0800
Subject: [PATCH 4/4] Revert more

---
 src/compiler/checker.ts   | 10 ++++------
 src/compiler/utilities.ts |  3 +--
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 514b5af7d2fea..80ccbf81a78ba 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -2295,11 +2295,9 @@ namespace ts {
                     ? Diagnostics._0_was_exported_here
                     : Diagnostics._0_was_imported_here;
 
-                // Non-null assertion is safe because `markSymbolOfAliasDeclarationIfTypeOnly` cannot return true
-                // for an ImportEqualsDeclaration without also being passed a defined symbol.
-                // `typeOnlyDeclaration.name` will be an Identifier for all valid cases, but may be undefined for
-                // invalid `export type * ...` syntax.
-                const name = unescapeLeadingUnderscores(tryCast(typeOnlyDeclaration.name, isIdentifier)?.escapedText ?? resolved!.escapedName);
+                // 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);
                 addRelatedInfo(error(node.moduleReference, message), createDiagnosticForNode(typeOnlyDeclaration, relatedMessage, name));
             }
         }
@@ -2730,7 +2728,7 @@ namespace ts {
         }
 
         /** Indicates that a symbol directly or indirectly resolves to a type-only import or export. */
-        function getTypeOnlyAliasDeclaration(symbol: Symbol): TypeOnlyCompatibleAliasDeclaration | NamespaceExport | ExportDeclaration | undefined {
+        function getTypeOnlyAliasDeclaration(symbol: Symbol): TypeOnlyCompatibleAliasDeclaration | undefined {
             if (!(symbol.flags & SymbolFlags.Alias)) {
                 return undefined;
             }
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index fc72453565194..62801c5bf0022 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -6216,8 +6216,7 @@ namespace ts {
     }
 
     export function typeOnlyDeclarationIsExport(typeOnlyDeclaration: Node) {
-        const kind = typeOnlyDeclaration.kind;
-        return kind === SyntaxKind.ExportSpecifier || kind === SyntaxKind.NamespaceExport || kind === SyntaxKind.ExportDeclaration;
+        return typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier;
     }
 
     function isPartOfPossiblyValidTypeOrAbstractComputedPropertyName(node: Node) {