fix: improve sourcemap support

Author: gera2ld

package.json

@@ -38,10 +38,10 @@
   },
   "dependencies": {
     "@babel/runtime": "^7.23.7",
+    "@jridgewell/sourcemap-codec": "^1.5.0",
     "@rollup/pluginutils": "^5.1.0",
     "estree-walker": "^3.0.3",
-    "is-reference": "^3.0.2",
-    "magic-string": "^0.30.7"
+    "is-reference": "^3.0.2"
   },
   "devDependencies": {
     "@gera2ld/plaid": "~2.7.0",

pnpm-lock.yaml

@@ -1,5 +1,5 @@
+import { encode } from '@jridgewell/sourcemap-codec';
 import { readFile } from 'fs/promises';
-import MagicString from 'magic-string';
 import type { Plugin } from 'rollup';
 import { collectGmApi, getMetadata } from './util';
 
@@ -32,7 +32,7 @@ export default (transform?: (metadata: string) => string): Plugin => {
      * Use `renderChunk` instead of `banner` to preserve the metadata after minimization.
      * Note that this plugin must be put after `@rollup/plugin-terser`.
      */
-    async renderChunk(code, chunk) {
+    async renderChunk(code, chunk, options) {
       const metadataFile =
         chunk.isEntry &&
         [chunk.facadeModuleId, ...Object.keys(chunk.modules)]
@@ -51,11 +51,27 @@ export default (transform?: (metadata: string) => string): Plugin => {
       }
       metadata = getMetadata(metadata, grantSet);
       if (transform) metadata = transform(metadata);
-      const s = new MagicString(code);
-      s.prepend(`${metadata}\n\n`);
+      let map = null;
+
+      if (options.sourcemap) {
+        const mappings = [
+          ...Array.from(metadata.split('\n'), () => []),
+          [],
+          ...Array.from(code.split('\n'), () => [[0, 0, 0, 0]]),
+        ];
+        map = {
+          version: 3,
+          file: chunk.fileName,
+          sources: [chunk.fileName],
+          sourcesContent: [code],
+          names: [],
+          mappings: encode(mappings),
+        };
+      }
+
       return {
-        code: s.toString(),
-        map: s.generateMap({ hires: 'boundary' }).toString(),
+        code: `${metadata}\n\n${code}`,
+        map,
       };
     },
   };