add transformer for emit add property to default export

Author: Kingwl

src/compiler/transformers/declarations.ts

@@ -1008,7 +1008,43 @@ namespace ts {
                             return createVariableStatement(/*modifiers*/ undefined, createVariableDeclarationList([varDecl]));
                         });
                         const namespaceDecl = createModuleDeclaration(/*decorators*/ undefined, ensureModifiers(input, isPrivate), input.name!, createModuleBlock(declarations), NodeFlags.Namespace);
-                        return [clean, namespaceDecl];
+
+                        if (!hasModifier(clean, ModifierFlags.ExportDefault)) {
+                            return [clean, namespaceDecl];
+                        }
+
+                        const modifierFlags = (getModifierFlags(clean) & ~ModifierFlags.ExportDefault) | ModifierFlags.Ambient;
+                        const cleanDeclaration = updateFunctionDeclaration(
+                            clean,
+                            /*decorators*/ undefined,
+                            createModifiersFromModifierFlags(modifierFlags),
+                            /*asteriskToken*/ undefined,
+                            clean.name,
+                            clean.typeParameters,
+                            clean.parameters,
+                            clean.type,
+                            /*body*/ undefined
+                        );
+
+                        const namespaceDeclaration = updateModuleDeclaration(
+                            namespaceDecl,
+                            /*decorators*/ undefined,
+                            createModifiersFromModifierFlags(modifierFlags),
+                            input.name!,
+                            createModuleBlock(declarations)
+                        );
+
+                        const exportDefaultDeclaration = createExportAssignment(
+                            /*decorators*/ undefined,
+                            /*modifiers*/undefined,
+                            /*isExportEquals*/false,
+                            clean.name!
+                        );
+
+                        resultHasExternalModuleIndicator = true;
+                        resultHasScopeMarker = true;
+
+                        return [cleanDeclaration, namespaceDeclaration, exportDefaultDeclaration];
                     }
                     else {
                         return clean;
@@ -1153,6 +1189,8 @@ namespace ts {
                         return preserveJsDoc(updateEnumMember(m, m.name, constValue !== undefined ? createLiteral(constValue) : undefined), m);
                     }))));
                 }
+                case SyntaxKind.ExportAssignment:
+                    return;
             }
             // Anything left unhandled is an error, so this should be unreachable
             return Debug.assertNever(input, `Unhandled top-level node in declaration emit: ${(ts as any).SyntaxKind[(input as any).kind]}`);

src/compiler/types.ts

@@ -3435,7 +3435,8 @@ namespace ts {
         | ModuleDeclaration
         | TypeAliasDeclaration
         | InterfaceDeclaration
-        | EnumDeclaration;
+        | EnumDeclaration
+        | ExportAssignment;
 
     /* @internal */
     export interface SymbolVisibilityResult {

tests/baselines/reference/exportDefaultNamespace.js

@@ -0,0 +1,24 @@
+//// [exportDefaultNamespace.ts]
+export default function someFunc() {
+    return 'hello!';
+}
+
+someFunc.someProp = 'yo';
+
+
+//// [exportDefaultNamespace.js]
+"use strict";
+exports.__esModule = true;
+function someFunc() {
+    return 'hello!';
+}
+exports["default"] = someFunc;
+someFunc.someProp = 'yo';
+
+
+//// [exportDefaultNamespace.d.ts]
+declare function someFunc(): string;
+declare namespace someFunc {
+    var someProp: string;
+}
+export default someFunc;

tests/baselines/reference/exportDefaultNamespace.symbols

@@ -0,0 +1,12 @@
+=== tests/cases/conformance/declarationEmit/exportDefaultNamespace.ts ===
+export default function someFunc() {
+>someFunc : Symbol(someFunc, Decl(exportDefaultNamespace.ts, 0, 0), Decl(exportDefaultNamespace.ts, 2, 1))
+
+    return 'hello!';
+}
+
+someFunc.someProp = 'yo';
+>someFunc.someProp : Symbol(someFunc.someProp, Decl(exportDefaultNamespace.ts, 2, 1))
+>someFunc : Symbol(someFunc, Decl(exportDefaultNamespace.ts, 0, 0), Decl(exportDefaultNamespace.ts, 2, 1))
+>someProp : Symbol(someFunc.someProp, Decl(exportDefaultNamespace.ts, 2, 1))
+

tests/baselines/reference/exportDefaultNamespace.types

@@ -0,0 +1,15 @@
+=== tests/cases/conformance/declarationEmit/exportDefaultNamespace.ts ===
+export default function someFunc() {
+>someFunc : typeof someFunc
+
+    return 'hello!';
+>'hello!' : "hello!"
+}
+
+someFunc.someProp = 'yo';
+>someFunc.someProp = 'yo' : "yo"
+>someFunc.someProp : string
+>someFunc : typeof someFunc
+>someProp : string
+>'yo' : "yo"
+

tests/cases/conformance/declarationEmit/exportDefaultNamespace.ts

@@ -0,0 +1,7 @@
+// @declaration: true
+
+export default function someFunc() {
+    return 'hello!';
+}
+
+someFunc.someProp = 'yo';