fix: build error with reserved keywords in CSS modules (#9439)

crates/rspack_plugin_css/src/utils.rs

@@ -12,7 +12,7 @@ use rspack_core::rspack_sources::{ConcatSource, RawStringSource};
 use rspack_core::ChunkGraph;
 use rspack_core::{
   to_identifier, Compilation, CompilerOptions, GenerateContext, PathData, ResourceData,
-  RuntimeGlobals,
+  RuntimeGlobals, RESERVED_IDENTIFIER,
 };
 use rspack_core::{CssExportsConvention, LocalIdentName};
 use rspack_error::{error, miette::Diagnostic, Result, TraceableError};
@@ -296,6 +296,9 @@ pub fn css_modules_exports_to_concatenate_module_string<'a>(
       .collect::<Vec<_>>()
       .join(" + \" \" + ");
     let mut identifier = to_identifier(key);
+    if RESERVED_IDENTIFIER.contains(identifier.as_ref()) {
+      identifier = Cow::Owned(format!("_{identifier}"));
+    }
     let mut i = 0;
     while used_identifiers.contains(&identifier) {
       identifier = Cow::Owned(format!("{identifier}{}", itoa!(i)));

packages/rspack-test-tools/tests/configCases/css/rspack-issue-9432/index.js

@@ -0,0 +1,15 @@
+import * as styles from "./index.module.css";
+
+styles["switch"];
+styles["default"];
+
+it("should works", async () => {
+	const fs = __non_webpack_require__("fs");
+	const path = __non_webpack_require__("path");
+	const js = await fs.promises.readFile(
+		path.resolve(__dirname, "./bundle0.js"),
+		"utf-8"
+	);
+	expect(js).toContain("_switch = ");
+	expect(js).toContain("_default = ");
+});

packages/rspack-test-tools/tests/configCases/css/rspack-issue-9432/index.module.css

@@ -0,0 +1,7 @@
+.switch {
+	display: block;
+}
+
+.default {
+	display: block;
+}

packages/rspack-test-tools/tests/configCases/css/rspack-issue-9432/rspack.config.js

@@ -0,0 +1,10 @@
+/** @type {import("@rspack/core").Configuration} */
+module.exports = {
+	target: "node",
+	optimization: {
+		concatenateModules: true
+	},
+	experiments: {
+		css: true
+	}
+};