fixup

Author: jakebailey

src/compiler/checker.ts

@@ -33885,7 +33885,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         }
 
         // TODO(jakebailey): write test case
-        if (isConstEnumObjectType(objectType) && !isStringLiteralLike(indexExpression) && !isPreservedConstEnum(objectType)) {
+        if (isConstEnumObjectType(objectType) && !isStringLiteralLike(indexExpression) && !isPreservedConstEnumUse(node, objectType)) {
             error(indexExpression, Diagnostics.A_const_enum_member_can_only_be_accessed_using_a_string_literal);
             return errorType;
         }
@@ -39817,7 +39817,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             (node.parent.kind === SyntaxKind.ExportSpecifier); // We allow reexporting const enums
 
         if (!ok || getIsolatedModules(compilerOptions)) {
-            if (!isPreservedConstEnum(type)) {
+            if (!isPreservedConstEnumUse(node, type)) {
                 if (!ok) {
                     // TODO(jakebailey): write negative test case
                     // TODO(jakebailey): make error message mention const enum preservation
@@ -39829,12 +39829,15 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         }
     }
 
-    function isPreservedConstEnum(type: Type) {
-        Debug.assert(!!(type.symbol.flags & SymbolFlags.ConstEnum));
-        const constEnumDeclaration = type.symbol.valueDeclaration as EnumDeclaration;
+    function isPreservedConstEnumUse(use: Node, enumType: Type) {
+        Debug.assert(!!(enumType.symbol.flags & SymbolFlags.ConstEnum));
+        const constEnumDeclaration = enumType.symbol.valueDeclaration as EnumDeclaration;
         const otherFile = getSourceFileOfNode(constEnumDeclaration);
         if (!otherFile.isDeclarationFile) {
             // This file can only have come from the current project.
+            if (constEnumDeclaration.flags & NodeFlags.Ambient && !isValidTypeOnlyAliasUseSite(use)) {
+                return false
+            }
             return shouldPreserveConstEnums(compilerOptions);
         }
         const redirect = host.getRedirectReferenceForResolutionFromSourceOfProject(otherFile.resolvedPath);