Recognize export * as default as a syntactic default export for syn…

…thetic default detection (microsoft#55985)

src/compiler/checker.ts

@@ -4022,7 +4022,10 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
     }
 
     function isSyntacticDefault(node: Node) {
-        return ((isExportAssignment(node) && !node.isExportEquals) || hasSyntacticModifier(node, ModifierFlags.Default) || isExportSpecifier(node));
+        return ((isExportAssignment(node) && !node.isExportEquals)
+            || hasSyntacticModifier(node, ModifierFlags.Default)
+            || isExportSpecifier(node)
+            || isNamespaceExport(node));
     }
 
     function getUsageModeForExpression(usage: Expression) {

tests/baselines/reference/exportAsNamespace5.js

@@ -0,0 +1,18 @@
+//// [tests/cases/conformance/es2020/modules/exportAsNamespace5.ts] ////
+
+//// [three.d.ts]
+export type Named = 0;
+declare const Named: 0;
+
+//// [two.d.ts]
+export * as default from "./three";
+
+//// [one.ts]
+import ns from "./two";
+type Alias = ns.Named;
+ns.Named;
+
+
+//// [one.js]
+import ns from "./two";
+ns.Named;

tests/baselines/reference/exportAsNamespace5.symbols

@@ -0,0 +1,27 @@
+//// [tests/cases/conformance/es2020/modules/exportAsNamespace5.ts] ////
+
+=== three.d.ts ===
+export type Named = 0;
+>Named : Symbol(Named, Decl(three.d.ts, 0, 0), Decl(three.d.ts, 1, 13))
+
+declare const Named: 0;
+>Named : Symbol(Named, Decl(three.d.ts, 0, 0), Decl(three.d.ts, 1, 13))
+
+=== two.d.ts ===
+export * as default from "./three";
+>default : Symbol(default, Decl(two.d.ts, 0, 6))
+
+=== one.ts ===
+import ns from "./two";
+>ns : Symbol(ns, Decl(one.ts, 0, 6))
+
+type Alias = ns.Named;
+>Alias : Symbol(Alias, Decl(one.ts, 0, 23))
+>ns : Symbol(ns, Decl(one.ts, 0, 6))
+>Named : Symbol(ns.Named, Decl(three.d.ts, 0, 0), Decl(three.d.ts, 1, 13))
+
+ns.Named;
+>ns.Named : Symbol(ns.Named, Decl(three.d.ts, 0, 0), Decl(three.d.ts, 1, 13))
+>ns : Symbol(ns, Decl(one.ts, 0, 6))
+>Named : Symbol(ns.Named, Decl(three.d.ts, 0, 0), Decl(three.d.ts, 1, 13))
+

tests/baselines/reference/exportAsNamespace5.types

@@ -0,0 +1,26 @@
+//// [tests/cases/conformance/es2020/modules/exportAsNamespace5.ts] ////
+
+=== three.d.ts ===
+export type Named = 0;
+>Named : 0
+
+declare const Named: 0;
+>Named : 0
+
+=== two.d.ts ===
+export * as default from "./three";
+>default : typeof import("three")
+
+=== one.ts ===
+import ns from "./two";
+>ns : typeof ns
+
+type Alias = ns.Named;
+>Alias : 0
+>ns : any
+
+ns.Named;
+>ns.Named : 0
+>ns : typeof ns
+>Named : 0
+

tests/cases/conformance/es2020/modules/exportAsNamespace5.ts

@@ -0,0 +1,14 @@
+// @module: esnext
+// @moduleResolution: bundler
+
+// @filename: three.d.ts
+export type Named = 0;
+declare const Named: 0;
+
+// @filename: two.d.ts
+export * as default from "./three";
+
+// @filename: one.ts
+import ns from "./two";
+type Alias = ns.Named;
+ns.Named;