fix: __vite__mapDeps code injection

packages/vite/src/node/plugins/importAnalysisBuild.ts

@@ -41,6 +41,12 @@ const preloadMarkerWithQuote = new RegExp(`['"]${preloadMarker}['"]`, 'g')
 
 const dynamicImportPrefixRE = /import\s*\(/
 
+// adjusted `convertSourceMap.mapFileCommentRegex` to match only at the last line
+// https://github.com/thlorenz/convert-source-map/blob/1afbeee2f2a42a3747c31dfcfc355387afdf42e2/index.js#L14
+const lastMapFileCommentRegex =
+  // eslint-disable-next-line regexp/no-super-linear-backtracking
+  /\/\/[@#][ \t]+sourceMappingURL=([^\s'"`]+)\n$|\/\*[@#][ \t]+sourceMappingURL=([^*]+?)[ \t]*\*\/\n$/
+
 function toRelativePath(filename: string, importer: string) {
   const relPath = path.posix.relative(path.posix.dirname(importer), filename)
   return relPath[0] === '.' ? relPath : `./${relPath}`
@@ -507,10 +513,9 @@ function __vite__mapDeps(indexes) {
   return indexes.map((i) => __vite__mapDeps.viteFileDeps[i])
 }\n`
 
-          // inject extra code before sourcemap comment
-          const mapFileCommentMatch =
-            convertSourceMap.mapFileCommentRegex.exec(code)
-          if (mapFileCommentMatch) {
+          // inject extra code before the last sourcemap comment
+          const mapFileCommentMatch = lastMapFileCommentRegex.exec(code)
+          if (config.build.sourcemap && mapFileCommentMatch) {
             s.appendRight(mapFileCommentMatch.index, mapDepsCode)
           } else {
             s.append(mapDepsCode)

playground/js-sourcemap/__tests__/js-sourcemap.spec.ts

@@ -137,23 +137,31 @@ describe.runIf(isBuild)('build tests', () => {
     const map = findAssetFile(/after-preload-dynamic.*\.js\.map/)
     expect(formatSourcemapForSnapshot(JSON.parse(map))).toMatchInlineSnapshot(`
       {
-        "mappings": "i3BAAA,OAAO,2BAAuB,EAAC,wBAE/B,QAAQ,IAAI,uBAAuB",
+        "mappings": "i3BAQA,OAAO,2BAAuB,EAAC,wBAE/B,QAAQ,IAAI,uBAAuB",
         "sources": [
           "../../after-preload-dynamic.js",
         ],
         "sourcesContent": [
-          "import('./dynamic/dynamic-foo')
+          "// false-positive sourcemap comment examples
+      //# sourceMappingURL=1.css.map
+      /*# sourceMappingURL=2.css.map */
+      ;\`
+      //# sourceMappingURL=3.css.map
+      /*# sourceMappingURL=4.css.map */
+      \`
+
+      import('./dynamic/dynamic-foo')
 
       console.log('after preload dynamic')
       ",
         ],
         "version": 3,
       }
     `)
-    //
+    // verify sourcemap comment is preserved at the last line
     const js = findAssetFile(/after-preload-dynamic.*\.js$/)
-    expect(js.trim().split('\n').at(-1)).toMatch(
-      /^\/\/# sourceMappingURL=after-preload-dynamic.*\.js\.map$/,
+    expect(js).toMatch(
+      /\n\/\/# sourceMappingURL=after-preload-dynamic.*\.js\.map\n$/,
     )
   })
 })

playground/js-sourcemap/after-preload-dynamic.js

@@ -1,3 +1,11 @@
+// false-positive sourcemap comment examples
+//# sourceMappingURL=1.css.map
+/*# sourceMappingURL=2.css.map */
+;`
+//# sourceMappingURL=3.css.map
+/*# sourceMappingURL=4.css.map */
+`
+
 import('./dynamic/dynamic-foo')
 
 console.log('after preload dynamic')