fix: should keep comments of esm export (#8168)

crates/rspack_plugin_javascript/src/dependency/esm/esm_export_expression_dependency.rs

@@ -39,19 +39,22 @@ pub struct ESMExportExpressionDependency {
  id: DependencyId,
  range: RealDependencyLocation,
  range_stmt: RealDependencyLocation,
+ prefix: String,
  declaration: Option<DeclarationId>,
 }
 
 impl ESMExportExpressionDependency {
  pub fn new(
  range: RealDependencyLocation,
  range_stmt: RealDependencyLocation,
+ prefix: String,
  declaration: Option<DeclarationId>,
  ) -> Self {
  Self {
  range,
  range_stmt,
  declaration,
+ prefix,
  id: DependencyId::default(),
  }
  }
@@ -171,7 +174,7 @@ impl DependencyTemplate for ESMExportExpressionDependency {
  source.replace(
  self.range_stmt.start,
  self.range.start,
- "/* ESM default export */ ",
+ format!("/* ESM default export */ {}", self.prefix).as_str(),
  None,
  );
  } else {
@@ -227,7 +230,7 @@ impl DependencyTemplate for ESMExportExpressionDependency {
  source.replace(
  self.range_stmt.start,
  self.range.start,
- &format!("{}(", content),
+ &format!("{}({}", content, self.prefix),
  None,
  );
  source.replace_with_enforce(

crates/rspack_plugin_javascript/src/parser_plugin/esm_export_dependency_parser_plugin.rs

@@ -1,7 +1,9 @@
+use itertools::Itertools;
 use rspack_core::{
  BoxDependency, ConstDependency, DependencyType, RealDependencyLocation, SpanExt,
 };
 use swc_core::atoms::Atom;
+use swc_core::common::comments::CommentKind;
 use swc_core::common::Spanned;
 
 use super::esm_import_dependency_parser_plugin::{ESMSpecifierData, ESM_SPECIFIER_TAG};
@@ -158,6 +160,20 @@ impl JavascriptParserPlugin for ESMExportDependencyParserPlugin {
  let dep: ESMExportExpressionDependency = ESMExportExpressionDependency::new(
  range.with_source(parser.source_map.clone()),
  statement_span.into(),
+ parser
+ .comments
+ .and_then(|c| c.get_leading(expr_span.lo))
+ .map(|c| {
+ c.iter()
+ .dedup()
+ .map(|c| match c.kind {
+ CommentKind::Block => format!("/*{}*/", c.text),
+ CommentKind::Line => format!("//{}\n", c.text),
+ })
+ .collect_vec()
+ .join("")
+ })
+ .unwrap_or_default(),
  match expr {
  ExportDefaultExpression::FnDecl(f) => {
  let start = f.span().real_lo();

packages/rspack-test-tools/tests/__snapshots__/Config.test.js.snap

@@ -459,6 +459,13 @@ exports[`config config/library/modern-module-force-concaten step should pass: .
 const d = 'd'
 `;
 
+exports[`config config/library/modern-module-force-concaten step should pass: ESM export should concat 1`] = `
+;// CONCATENATED MODULE: ./a.js
+const a = 'a'
+
+export { a };
+`;
+
 exports[`config config/library/modern-module-force-concaten step should pass: external module should bail out when bundling 1`] = `
 import { createRequire as __WEBPACK_EXTERNAL_createRequire } from "module";
 var __webpack_modules__ = ({
@@ -551,13 +558,6 @@ const value = foo + (bar_default())
 export { value };
 `;
 
-exports[`config config/library/modern-module-force-concaten step should pass: ESM export should concat 1`] = `
-;// CONCATENATED MODULE: ./a.js
-const a = 'a'
-
-export { a };
-`;
-
 exports[`config config/library/modern-module-force-concaten step should pass: unambiguous should bail out 1`] = `const c = 'c'`;
 
 exports[`config config/optimization/minimizer-esm-asset exported tests minimizing an asset file of esm type should success 1`] = `console.log(import.meta.url);export const a=1;`;

packages/rspack-test-tools/tests/configCases/parsing/harmony-export-comment/index.js

@@ -0,0 +1,16 @@
+import { requestEngine } from './share';
+import used from './used';
+
+used;
+
+const content = __non_webpack_require__("fs").readFileSync(__filename, 'utf-8');
+const pureComment = "/* #__PURE__ */";
+it("should keep pure comment of unused export default", () => {
+ const methodName = "createRequest";
+ expect(content).toContain(`${pureComment}${methodName}`)
+});
+
+it("should keep pure comment of used export default", () => {
+ const methodName = "function __WEBPACK_DEFAULT_EXPORT__()";
+ expect(content).toContain(`${pureComment}${methodName}`)
+});

packages/rspack-test-tools/tests/configCases/parsing/harmony-export-comment/rspack.config.js

@@ -0,0 +1,15 @@
+/**
+ * @type {import('@rspack/core').Configuration}
+ */
+module.exports = {
+ entry: "./index.js",
+ node: {
+ __dirname: false,
+ __filename: false
+ },
+ optimization: {
+ sideEffects: false,
+ concatenateModules: false,
+ innerGraph: false
+ }
+}

packages/rspack-test-tools/tests/configCases/parsing/harmony-export-comment/share.js

@@ -0,0 +1,9 @@
+function createRequest() {
+}
+function requestEngine() {
+
+}
+
+export default /* #__PURE__ */ createRequest();
+
+export { requestEngine };

packages/rspack-test-tools/tests/configCases/parsing/harmony-export-comment/used.js

@@ -0,0 +1,9 @@
+
+function fun2() {
+
+}
+
+export default /* #__PURE__ */ function () {
+}
+
+export { fun2 };

packages/rspack-test-tools/tests/treeShakingCases/pure_comments_magic_comments/__snapshots__/treeshaking.snap.txt

@@ -10,7 +10,7 @@ function res() {
  answer;
 }
 const a = 3;
-/* unused ESM default export */ var __WEBPACK_DEFAULT_EXPORT__ = ((/* unused pure expression or super */ null && (res())));
+/* unused ESM default export */ var __WEBPACK_DEFAULT_EXPORT__ = (/*#__PURE__*/(/* unused pure expression or super */ null && (res())));
 
 
 }),