feat: support eval undefined

crates/rspack_plugin_javascript/src/utils/eval/eval_unary_expr.rs

@@ -30,6 +30,10 @@ fn eval_typeof(
     let mut res = BasicEvaluatedExpression::with_range(expr.span.real_lo(), expr.span.hi.0);
     res.set_string("string".to_string());
     Some(res)
+  } else if arg.is_undefined() {
+    let mut res = BasicEvaluatedExpression::with_range(expr.span.real_lo(), expr.span.hi.0);
+    res.set_string("undefined".to_string());
+    Some(res)
   } else {
     // TODO: `arg.is_wrapped()`...
     None

crates/rspack_plugin_javascript/src/utils/eval/mod.rs

@@ -218,7 +218,7 @@ impl BasicEvaluatedExpression {
   pub fn as_bool(&self) -> Option<Boolean> {
     if self.truthy {
       Some(true)
-    } else if self.falsy || self.nullish == Some(true) || self.is_null() {
+    } else if self.falsy || self.nullish == Some(true) || self.is_null() || self.is_undefined() {
       Some(false)
     } else {
       self.boolean
@@ -284,6 +284,11 @@ impl BasicEvaluatedExpression {
     self.side_effects = false
   }
 
+  pub fn set_undefined(&mut self) {
+    self.ty = Ty::Undefined;
+    self.side_effects = false;
+  }
+
   pub fn set_number(&mut self, number: Number) {
     self.ty = Ty::Number;
     self.number = Some(number);

crates/rspack_plugin_javascript/src/visitors/dependency/parser/mod.rs

@@ -758,10 +758,16 @@ impl JavascriptParser<'_> {
             .or_else(|| {
               let mut eval =
                 BasicEvaluatedExpression::with_range(ident.span.real_lo(), ident.span.hi.0);
-              eval.set_identifier(
-                ident.sym.to_string(),
-                ExportedVariableInfo::Name(ident.sym.to_string()),
-              );
+
+              if ident.sym.eq("undefined") {
+                eval.set_undefined();
+              } else {
+                eval.set_identifier(
+                  ident.sym.to_string(),
+                  ExportedVariableInfo::Name(ident.sym.to_string()),
+                );
+              }
+
               Some(eval)
             });
         };

packages/rspack/tests/configCases/parsing/eval-null-in-none-mode/a.js

@@ -0,0 +1 @@
+module.exports = "a";

packages/rspack/tests/configCases/parsing/eval-null-in-none-mode/index.js

@@ -0,0 +1,4 @@
+it("should evaluate null", function () {
+	expect(null ? require("fail") : require("./a.js")).toBe("a");
+	if (null) require("fail");
+});

packages/rspack/tests/configCases/parsing/eval-null-in-none-mode/webpack.config.js

@@ -0,0 +1,3 @@
+module.exports = {
+	mode: "none"
+};

packages/rspack/tests/configCases/parsing/eval-undefined-in-none-mode/a.js

@@ -0,0 +1 @@
+module.exports = "a";

packages/rspack/tests/configCases/parsing/eval-undefined-in-none-mode/index.js

@@ -0,0 +1,5 @@
+it("should evaluate undefined", function () {
+	expect(undefined ? require("fail") : require("./a")).toBe("a");
+	if (undefined) require("fail");
+	undefined && require("fail");
+});

packages/rspack/tests/configCases/parsing/eval-undefined-in-none-mode/webpack.config.js

@@ -0,0 +1,3 @@
+module.exports = {
+	mode: "none"
+};