fix(build): namespace virtual module ids in sourcemap sources

Author: pi0

src/build/plugins.ts

@@ -8,7 +8,7 @@ import { unwasm } from "unwasm/plugin";
 import { routeMeta } from "./plugins/route-meta.ts";
 import { serverMain } from "./plugins/server-main.ts";
 import { virtual, virtualDeps } from "./plugins/virtual.ts";
-import { sourcemapMinify } from "./plugins/sourcemap-min.ts";
+import { sourcemap } from "./plugins/sourcemap.ts";
 import { raw, RESOLVED_RE as rawModulesRE } from "./plugins/raw.ts";
 import { importAttributes } from "./plugins/import-attributes.ts";
 import { externals } from "./plugins/externals.ts";
@@ -75,13 +75,14 @@ export async function baseBuildPlugins(nitro: Nitro, base: BaseBuildConfig) {
     );
   }
 
-  // Sourcemap minify
-  if (
-    nitro.options.sourcemap &&
-    !nitro.options.dev &&
-    nitro.options.experimental.sourcemapMinify !== false
-  ) {
-    plugins.push(sourcemapMinify());
+  // Sourcemap
+  if (nitro.options.sourcemap && !nitro.options.dev) {
+    plugins.push(
+      sourcemap({
+        virtualIds: virtualPlugin.api.modules.keys(),
+        minify: nitro.options.experimental.sourcemapMinify !== false,
+      })
+    );
   }
 
   return plugins;

src/build/plugins/sourcemap-min.ts

@@ -0,0 +1,58 @@
+import type { ExistingRawSourceMap, Plugin } from "rollup";
+
+// Ids of virtual modules already namespaced by their own plugins
+const VIRTUAL_PREFIX_RE = /(?:^|\/)(virtual:.+)$/;
+
+export function sourcemap(opts: { virtualIds: Iterable<string>; minify: boolean }): Plugin {
+  const virtualIds = [...opts.virtualIds];
+
+  return {
+    name: "nitro:sourcemap",
+    generateBundle(_options, bundle) {
+      for (const [key, asset] of Object.entries(bundle)) {
+        // Only process sourcemaps
+        if (!key.endsWith(".map") || !("source" in asset) || typeof asset.source !== "string") {
+          continue;
+        }
+
+        // Parse sourcemap
+        const sourcemap: ExistingRawSourceMap = JSON.parse(asset.source);
+
+        // Virtual modules have no file on disk. Bundlers emit their ids as (relative)
+        // paths, making consumers warn about missing sources. Namespace them instead.
+        if (sourcemap.sources) {
+          sourcemap.sources = sourcemap.sources.map((source) =>
+            source ? virtualSource(source, virtualIds) : source
+          );
+        }
+
+        if (opts.minify) {
+          // Remove sourcesContent
+          delete sourcemap.sourcesContent;
+
+          // Remove x_google_ignoreList
+          delete sourcemap.x_google_ignoreList;
+
+          if ((sourcemap.sources || []).every((s) => s?.includes("node_modules"))) {
+            sourcemap.mappings = ""; // required key
+          }
+        }
+
+        asset.source = JSON.stringify(sourcemap);
+      }
+    },
+  };
+}
+
+function virtualSource(source: string, virtualIds: string[]): string {
+  const namespaced = VIRTUAL_PREFIX_RE.exec(source)?.[1];
+  if (namespaced) {
+    return namespaced;
+  }
+  for (const id of virtualIds) {
+    if (source === id || source.endsWith(`/${id}`)) {
+      return `virtual:${id}`;
+    }
+  }
+  return source;
+}

src/build/plugins/sourcemap.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from "vitest";
-import { sourcemapMinify } from "../../src/build/plugins/sourcemap-min.ts";
+import { sourcemap } from "../../src/build/plugins/sourcemap.ts";
 
 type BundleAsset = { type: "asset"; source: string };
 
@@ -20,8 +20,14 @@ function createSourcemapAsset(sourcemap: {
   };
 }
 
-function runPlugin(bundle: Record<string, BundleAsset>) {
-  const plugin = sourcemapMinify();
+function runPlugin(
+  bundle: Record<string, BundleAsset>,
+  opts: { virtualIds?: string[]; minify?: boolean } = {}
+) {
+  const plugin = sourcemap({
+    virtualIds: opts.virtualIds || [],
+    minify: opts.minify ?? true,
+  });
   (plugin.generateBundle as Function).call(null, {}, bundle);
   const results: Record<string, ReturnType<typeof JSON.parse>> = {};
   for (const [key, asset] of Object.entries(bundle)) {
@@ -32,7 +38,7 @@ function runPlugin(bundle: Record<string, BundleAsset>) {
   return results;
 }
 
-describe("sourcemapMinify", () => {
+describe("sourcemap", () => {
   it("removes sourcesContent from all sourcemaps", () => {
     const bundle = {
       "index.mjs.map": createSourcemapAsset({
@@ -109,4 +115,41 @@ describe("sourcemapMinify", () => {
     const results = runPlugin(bundle);
     expect(results["chunk.mjs.map"].mappings).toBe("");
   });
+
+  it("namespaces virtual module sources", () => {
+    const bundle = {
+      "_chunks/app.mjs.map": createSourcemapAsset({
+        sources: [
+          "../../../../workspace/app/#nitro/virtual/app",
+          "../../../../workspace/app/#virtual-route",
+          "../../../../workspace/app/virtual:nitro:raw:/workspace/app/server/files/test.txt.js",
+          "../../src/routes/index.ts",
+        ],
+      }),
+    };
+    const results = runPlugin(bundle, {
+      virtualIds: ["#nitro/virtual/app", "#virtual-route"],
+    });
+    expect(results["_chunks/app.mjs.map"].sources).toEqual([
+      "virtual:#nitro/virtual/app",
+      "virtual:#virtual-route",
+      "virtual:nitro:raw:/workspace/app/server/files/test.txt.js",
+      "../../src/routes/index.ts",
+    ]);
+  });
+
+  it("keeps sourcesContent when minify is disabled", () => {
+    const bundle = {
+      "index.mjs.map": createSourcemapAsset({
+        sources: ["../../workspace/app/#nitro/virtual/app"],
+        sourcesContent: ["export default 42;"],
+      }),
+    };
+    const results = runPlugin(bundle, {
+      virtualIds: ["#nitro/virtual/app"],
+      minify: false,
+    });
+    expect(results["index.mjs.map"].sourcesContent).toEqual(["export default 42;"]);
+    expect(results["index.mjs.map"].sources).toEqual(["virtual:#nitro/virtual/app"]);
+  });
 });