Return correct values for unkown namespace members (#4684)

src/ast/variables/NamespaceVariable.ts

@@ -1,11 +1,14 @@
-import type { AstContext } from '../../Module';
 import type Module from '../../Module';
+import type { AstContext } from '../../Module';
 import { getToStringTagValue, MERGE_NAMESPACES_VARIABLE } from '../../utils/interopHelpers';
 import type { RenderOptions } from '../../utils/renderHelpers';
 import { getSystemExportStatement } from '../../utils/systemJsRendering';
 import type Identifier from '../nodes/Identifier';
 import type { LiteralValueOrUnknown } from '../nodes/shared/Expression';
+import { UnknownValue } from '../nodes/shared/Expression';
 import type ChildScope from '../scopes/ChildScope';
+import type { ObjectPath } from '../utils/PathTracker';
+import { SymbolToStringTag } from '../utils/PathTracker';
 import Variable from './Variable';
 
 export default class NamespaceVariable extends Variable {
@@ -29,9 +32,11 @@ export default class NamespaceVariable extends Variable {
 		this.name = identifier.name;
 	}
 
-	getLiteralValueAtPath(): LiteralValueOrUnknown {
-		// This can only happen for Symbol.toStringTag right now
-		return 'Module';
+	getLiteralValueAtPath(path: ObjectPath): LiteralValueOrUnknown {
+		if (path[0] === SymbolToStringTag) {
+			return 'Module';
+		}
+		return UnknownValue;
 	}
 
 	getMemberVariables(): { [name: string]: Variable } {

test/function/samples/namespace-literal-value/_config.js

@@ -0,0 +1,9 @@
+const assert = require('node:assert');
+
+module.exports = {
+	description: 'does not simplify accessing unknown properties from namespaces',
+	exports({ isNull }) {
+		assert.strictEqual(isNull('a'), true);
+		assert.strictEqual(isNull('b'), false);
+	}
+};

test/function/samples/namespace-literal-value/main.js

@@ -0,0 +1,3 @@
+import * as ns from './namespace';
+
+export const isNull = prop => (ns[prop] === null ? true : false);

test/function/samples/namespace-literal-value/namespace.js

@@ -0,0 +1,2 @@
+export const a = null;
+export const b = true;