Do not handle declarations in modules without side effects as TDZ (#5322)

Author: lukastaegert

src/ast/nodes/Identifier.ts

@@ -243,7 +243,9 @@ export default class Identifier extends NodeBase implements PatternNode {
 			return (this.isTDZAccess = true);
 		}
 
-		if (!this.variable.initReached) {
+		// We ignore the case where the module is not yet executed because
+		// moduleSideEffects are false.
+		if (!this.variable.initReached && this.scope.context.module.isExecuted) {
 			// Either a const/let TDZ violation or
 			// var use before declaration was encountered.
 			return (this.isTDZAccess = true);

test/form/samples/tree-shake-nested-call-no-module-side-effects/_config.js

@@ -0,0 +1,8 @@
+module.exports = defineTest({
+	description: 'properly tree-shakes nested function calls when moduleSideEffects are disabled',
+	options: {
+		treeshake: {
+			moduleSideEffects: false
+		}
+	}
+});

test/form/samples/tree-shake-nested-call-no-module-side-effects/_expected.js

@@ -0,0 +1,4 @@
+const main = () => {
+};
+
+export { main };

test/form/samples/tree-shake-nested-call-no-module-side-effects/alpha.js

@@ -0,0 +1,7 @@
+const doNothing = () => {};
+
+const alpha = () => {
+	doNothing();
+};
+
+export { alpha };

test/form/samples/tree-shake-nested-call-no-module-side-effects/main.js

@@ -0,0 +1,7 @@
+import { alpha } from "./alpha";
+
+const main = () => {
+	alpha();
+};
+
+export { main };