fix: extracted comments should be behind the shebang (#12380)

* Add tests

* Fix

* Update crates/rspack_plugin_swc_js_minimizer/src/lib.rs

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: CPunisher

crates/rspack_plugin_swc_js_minimizer/src/lib.rs

@@ -298,7 +298,7 @@ async fn process_assets(&self, compilation: &mut Compilation) -> Result<()> {
           }
         };
 
-        let output = match javascript_compiler.minify(
+        let mut output = match javascript_compiler.minify(
           swc_core::common::FileName::Custom(filename.to_string()),
           input,
           js_minify_options,
@@ -316,33 +316,80 @@ async fn process_assets(&self, compilation: &mut Compilation) -> Result<()> {
             },
         };
 
-        let source = if let Some(source_map) = output.map {
-          SourceMapSource::new(SourceMapSourceOptions {
-            value: output.code,
-            name: filename,
-            source_map,
-            original_source: None,
-            inner_source_map: input_source_map,
-            remove_original_source: true,
-          })
-          .boxed()
-        } else {
-          RawStringSource::from(output.code).boxed()
-        };
-        let source = if let Some(Some(banner)) = extract_comments_option.map(|option| option.banner)
-          && all_extracted_comments
+        let banner = if all_extracted_comments
           .lock()
           .expect("all_extract_comments lock failed")
-          .contains_key(filename)
-        {
-          ConcatSource::new([
-            RawStringSource::from(banner).boxed(),
-            RawStringSource::from_static("\n").boxed(),
-            source
-          ]).boxed()
-        } else {
-          source
+          .contains_key(filename) {
+            extract_comments_option.and_then(|option| option.banner)
+          } else {
+            None
+          };
+
+        let source = match banner {
+            Some(banner) => {
+              // There are two cases with banner:
+              // 1. There's no shebang, we just prepend the banner to the code.
+              // 2. There's a shebang, we prepend the shebang, then the banner, then the code.
+
+              let mut shebang = None;
+              if output.code.starts_with("#!") {
+                if let Some(line_pos) = output.code.find('\n') {
+                  shebang = Some(output.code[0..line_pos + 1].to_string());
+                  output.code = output.code[line_pos + 1..].to_string();
+                } else {
+                  // Handle shebang without newline - treat entire content as shebang
+                  shebang = Some(output.code.clone());
+                  output.code = String::new();
+                }
+              }
+
+              let source = if let Some(source_map) = output.map {
+                SourceMapSource::new(SourceMapSourceOptions {
+                  value: output.code,
+                  name: filename,
+                  source_map,
+                  original_source: None,
+                  inner_source_map: input_source_map,
+                  remove_original_source: true,
+                })
+                .boxed()
+              } else {
+                RawStringSource::from(output.code).boxed()
+              };
+
+              if let Some(shebang) = shebang {
+                ConcatSource::new([
+                  RawStringSource::from(shebang).boxed(),
+                  RawStringSource::from(banner).boxed(),
+                  RawStringSource::from_static("\n").boxed(),
+                  source
+                ]).boxed()
+              } else {
+                ConcatSource::new([
+                  RawStringSource::from(banner).boxed(),
+                  RawStringSource::from_static("\n").boxed(),
+                  source
+                ]).boxed()
+              }
+            },
+            None => {
+              // If there's no banner, we don't need to handle `output.code` at all.
+              if let Some(source_map) = output.map {
+                SourceMapSource::new(SourceMapSourceOptions {
+                  value: output.code,
+                  name: filename,
+                  source_map,
+                  original_source: None,
+                  inner_source_map: input_source_map,
+                  remove_original_source: true,
+                })
+                .boxed()
+              } else {
+                RawStringSource::from(output.code).boxed()
+              }
+            },
         };
+
         original.set_source(Some(source));
         original.get_info_mut().minimized.replace(true);
       }

tests/rspack-test/configCases/rslib/hashbang-and-extract-comments/a.js

@@ -0,0 +1,30 @@
+/*! Legal Comment */
+
+/**
+ * @preserve Copyright 2009 SomeThirdParty.
+ * Here is the full license text and copyright
+ * notice for this file. Note that the notice can span several
+ * lines and is only terminated by the closing star and slash:
+ */
+
+/**
+ * Utility functions for the foo package.
+ * @license Apache-2.0
+ */
+
+/*! Legal Foo */
+
+// Foo
+
+/*
+ Foo Bar
+ */
+
+// @license
+
+/*
+ * Foo
+ */
+// @lic
+
+module.exports = "aaaa";

tests/rspack-test/configCases/rslib/hashbang-and-extract-comments/index.js

@@ -0,0 +1,9 @@
+#!/usr/bin/env node
+
+import os from "os";
+import a from "./a.js";
+
+export function hello() {
+	console.log(a);
+	return "hello from rslib hashbang" + os.platform();
+}

tests/rspack-test/configCases/rslib/hashbang-and-extract-comments/rspack.config.js

@@ -0,0 +1,80 @@
+const {
+	rspack,
+	experiments: { RslibPlugin, EsmLibraryPlugin }
+} = require("@rspack/core");
+
+/** @type {import("@rspack/core").Configuration} */
+const baseConfig = {
+	entry: {
+		index: "./index.js"
+	},
+	target: "node",
+	node: {
+		__filename: false,
+		__dirname: false
+	},
+	optimization: {
+		minimize: true,
+		minimizer: [
+			new rspack.SwcJsMinimizerRspackPlugin({
+				extractComments: true
+			})
+		]
+	}
+};
+
+module.exports = [
+	// CJS output
+	{
+		...baseConfig,
+		output: {
+			library: {
+				type: "commonjs"
+			}
+		},
+		plugins: [new RslibPlugin()]
+	},
+	// ESM output (without EsmLibraryPlugin)
+	{
+		...baseConfig,
+		experiments: {
+			outputModule: true
+		},
+		externals: {
+			os: "module os"
+		},
+		output: {
+			module: true,
+			library: {
+				type: "modern-module"
+			}
+		},
+		plugins: [new RslibPlugin()]
+	},
+	// ESM output (with EsmLibraryPlugin)
+	{
+		...baseConfig,
+		experiments: {
+			outputModule: true
+		},
+		externals: {
+			os: "module os"
+		},
+		output: {
+			module: true,
+			library: {
+				type: "modern-module"
+			}
+		},
+		plugins: [new RslibPlugin(), new EsmLibraryPlugin()]
+	},
+	// Test entry
+	{
+		entry: "./test.js",
+		target: "node",
+		node: {
+			__filename: false,
+			__dirname: false
+		}
+	}
+];

tests/rspack-test/configCases/rslib/hashbang-and-extract-comments/test.config.js

@@ -0,0 +1,6 @@
+/** @type {import("../../../..").TConfigCaseConfig} */
+module.exports = {
+	findBundle: function (i, options) {
+		return ["./bundle3.js"];
+	}
+};

tests/rspack-test/configCases/rslib/hashbang-and-extract-comments/test.js

@@ -0,0 +1,17 @@
+const path = require('path');
+const fs = require('fs');
+
+const testCases = [
+	{ name: 'CJS', file: 'bundle0.js' },
+	{ name: 'ESM', file: 'bundle1.mjs' },
+	{ name: 'ESM (with EsmLibraryPlugin)', file: 'bundle2.mjs' }
+];
+
+testCases.forEach(({ name, file }) => {
+	it(`should include hashbang at the first line (${name})`, () => {
+		const filePath = path.resolve(__dirname, file);
+		const content = fs.readFileSync(filePath, 'utf-8');
+
+		expect(content.startsWith('#!/usr/bin/env node\n')).toBe(true);
+	});
+});