Use merged symbol to pick up js-alias-merged members on export assignments (#37162)

Author: weswigham

src/compiler/checker.ts

@@ -6138,7 +6138,7 @@ namespace ts {
                         const varName = getUnusedName(name, symbol);
                         // We have to use `getWidenedType` here since the object within a json file is unwidened within the file
                         // (Unwidened types can only exist in expression contexts and should never be serialized)
-                        const typeToSerialize = getWidenedType(getTypeOfSymbol(symbol));
+                        const typeToSerialize = getWidenedType(getTypeOfSymbol(getMergedSymbol(symbol)));
                         if (isTypeRepresentableAsFunctionNamespaceMerge(typeToSerialize, symbol)) {
                             // If there are no index signatures and `typeToSerialize` is an object type, emit as a namespace instead of a const
                             serializeAsFunctionNamespaceMerge(typeToSerialize, symbol, varName, isExportAssignment ? ModifierFlags.None : ModifierFlags.Export);

tests/baselines/reference/jsDeclarationsExportDoubleAssignmentInClosure.js

@@ -0,0 +1,25 @@
+//// [index.js]
+// @ts-nocheck
+function foo() {
+    module.exports = exports = function (o) {
+        return (o == null) ? create(base) : defineProperties(Object(o), descriptors);
+    };
+    exports.methods = methods;
+}
+
+//// [index.js]
+// @ts-nocheck
+function foo() {
+    module.exports = exports = function (o) {
+        return (o == null) ? create(base) : defineProperties(Object(o), descriptors);
+    };
+    exports.methods = methods;
+}
+
+
+//// [index.d.ts]
+declare function _exports(o: any): any;
+declare namespace _exports {
+    export const methods: any;
+}
+export = _exports;

tests/baselines/reference/jsDeclarationsExportDoubleAssignmentInClosure.symbols

@@ -0,0 +1,22 @@
+=== tests/cases/conformance/jsdoc/declarations/index.js ===
+// @ts-nocheck
+function foo() {
+>foo : Symbol(foo, Decl(index.js, 0, 0))
+
+    module.exports = exports = function (o) {
+>module.exports : Symbol("tests/cases/conformance/jsdoc/declarations/index", Decl(index.js, 0, 0))
+>module : Symbol(export=, Decl(index.js, 1, 16))
+>exports : Symbol(export=, Decl(index.js, 1, 16))
+>exports : Symbol("tests/cases/conformance/jsdoc/declarations/index", Decl(index.js, 0, 0))
+>o : Symbol(o, Decl(index.js, 2, 41))
+
+        return (o == null) ? create(base) : defineProperties(Object(o), descriptors);
+>o : Symbol(o, Decl(index.js, 2, 41))
+>Object : Symbol(Object, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>o : Symbol(o, Decl(index.js, 2, 41))
+
+    };
+    exports.methods = methods;
+>exports : Symbol(methods, Decl(index.js, 4, 6))
+>methods : Symbol(methods, Decl(index.js, 4, 6))
+}

tests/baselines/reference/jsDeclarationsExportDoubleAssignmentInClosure.types

@@ -0,0 +1,39 @@
+=== tests/cases/conformance/jsdoc/declarations/index.js ===
+// @ts-nocheck
+function foo() {
+>foo : () => void
+
+    module.exports = exports = function (o) {
+>module.exports = exports = function (o) {        return (o == null) ? create(base) : defineProperties(Object(o), descriptors);    } : any
+>module.exports : any
+>module : { "\"tests/cases/conformance/jsdoc/declarations/index\"": any; }
+>exports : any
+>exports = function (o) {        return (o == null) ? create(base) : defineProperties(Object(o), descriptors);    } : (o: any) => any
+>exports : any
+>function (o) {        return (o == null) ? create(base) : defineProperties(Object(o), descriptors);    } : (o: any) => any
+>o : any
+
+        return (o == null) ? create(base) : defineProperties(Object(o), descriptors);
+>(o == null) ? create(base) : defineProperties(Object(o), descriptors) : any
+>(o == null) : boolean
+>o == null : boolean
+>o : any
+>null : null
+>create(base) : error
+>create : error
+>base : error
+>defineProperties(Object(o), descriptors) : error
+>defineProperties : error
+>Object(o) : any
+>Object : ObjectConstructor
+>o : any
+>descriptors : error
+
+    };
+    exports.methods = methods;
+>exports.methods = methods : error
+>exports.methods : any
+>exports : any
+>methods : any
+>methods : error
+}

tests/cases/conformance/jsdoc/declarations/jsDeclarationsExportDoubleAssignmentInClosure.ts

@@ -0,0 +1,12 @@
+// @allowJs: true
+// @checkJs: true
+// @outDir: ./out
+// @declaration: true
+// @filename: index.js
+// @ts-nocheck
+function foo() {
+    module.exports = exports = function (o) {
+        return (o == null) ? create(base) : defineProperties(Object(o), descriptors);
+    };
+    exports.methods = methods;
+}