Merge pull request #14835 from webpack/evaluate-undefined

sokra · web-flow · commit 2eef4b3eaaa0 · 2021-11-26T08:35:28.000+01:00
evaluate undefined to type "undefined"
diff --git a/lib/javascript/JavascriptParser.js b/lib/javascript/JavascriptParser.js
@@ -935,6 +935,13 @@ class JavascriptParser extends Parser {
 				.setString("undefined")
 				.setRange(expr.range);
 		});
+		this.hooks.evaluate.for("Identifier").tap("JavascriptParser", expr => {
+			if (/** @type {IdentifierNode} */ (expr).name === "undefined") {
+				return new BasicEvaluatedExpression()
+					.setUndefined()
+					.setRange(expr.range);
+			}
+		});
 		/**
 		 * @param {string} exprType expression type name
 		 * @param {function(ExpressionNode): GetInfoResult | undefined} getInfo get info
diff --git a/test/cases/parsing/evaluate/index.js b/test/cases/parsing/evaluate/index.js
@@ -3,6 +3,12 @@ it("should evaluate null", function () {
 	if (null) require("fail");
 });
 
+it("should evaluate undefined", function () {
+	const y = undefined ? require("fail") : require("./a");
+	if (undefined) require("fail");
+	undefined && require("fail");
+});
+
 it("should evaluate logical expression", function () {
 	const value1 = "hello" || require("fail");
 	const value2 = typeof require === "function" || require("fail");
