fix(v8): fetch replace_with crates from crates.io

lib/update-v8/updateCrates.js

@@ -1,6 +1,7 @@
 import semver from 'semver';
 import * as TOML from 'smol-toml';
 import { promises as fs } from 'node:fs';
+import os from 'node:os';
 import path from 'node:path';
 
 import { removeDirectory } from './util.js';
@@ -15,6 +16,7 @@ export default function updateCrates() {
         enumerateTemporalDependencies(),
         removeExistingCrates(),
         vendorCrates(),
+        fetchPlaceholderCrates(),
         buildManifest(),
         generateLockfile(),
         updateGYP(),
@@ -78,15 +80,23 @@ function vendorCrates() {
       await fs.mkdir(nodeVendor);
 
       const subtasks = [];
-      const rustVersions = [];
+      ctx.rustVersions = [];
+      ctx.placeholderCrates = [];
       for (const dir of await fs.readdir(chromiumVendor)) {
         const crate = await getCrateInfo(dir);
         if (!crate || !ctx.temporalCrates.has(`${crate.name}@${crate.version}`)) continue;
         if (crate.name === 'temporal_capi') {
           ctx.temporalCAPIDirectory = dir;
         }
+        // Fetch replace_with placeholders from crates.io.
+        // This is a stop-gap fix that only works as long as the
+        // See https://chromium-review.googlesource.com/c/chromium/src/+/8527739
+        if (crate.metadata?.gnrt?.is_placeholder) {
+          ctx.placeholderCrates.push({ dir, name: crate.name, version: crate.version });
+          continue;
+        }
         if (crate['rust-version']) {
-          rustVersions.push(crate['rust-version']);
+          ctx.rustVersions.push(crate['rust-version']);
         }
         subtasks.push({
           title: dir,
@@ -100,11 +110,6 @@ function vendorCrates() {
         });
       }
 
-      if (rustVersions.length) {
-        const msrv = rustVersions.map(semver.coerce).reduce((a, b) => (semver.gt(a, b) ? a : b));
-        ctx.msrv = `${msrv.major}.${msrv.minor}`;
-      }
-
       return task.newListr(subtasks, { concurrent: ctx.concurrent });
 
       async function getCrateInfo(crate) {
@@ -121,10 +126,75 @@ function vendorCrates() {
   };
 }
 
+// TODO(joyeecheung): Instead of fetching the crates from crates.io,
+// generate the replacement crates from Chromium's data. e.g.
+// For `replace_with = "//third_party/rust/icu4x_data:lib"`
+// in gnrt_config.toml, copy the `.rs.data` files that the dependent
+// crates use (`impl_<marker>!(Baked)` in their provider.rs) from
+// third_party/rust/icu4x_data/src/data/common and generate a data/mod.rs in the
+// upstream crate layout.
+// See https://github.com/nodejs/node-core-utils/pull/1117
+function fetchPlaceholderCrates() {
+  return {
+    title: 'Fetch placeholder crates from crates.io',
+    skip: (ctx) => ctx.placeholderCrates.length === 0 && 'No placeholder crates',
+    task: async(ctx) => {
+      const nodeVendor = path.join(ctx.nodeDir, nodeCratesDir, 'vendor');
+      const chromiumPatches = path.join(ctx.nodeDir, chromiumCratesDir, 'patches');
+      for (const { dir, name } of ctx.placeholderCrates) {
+        try {
+          await fs.access(path.join(chromiumPatches, dir));
+        } catch {
+          continue;
+        }
+        throw new Error(`Detected Chromium patches ${name} in ${chromiumPatches}/${dir}, ` +
+          'the stop-gap fix of fetching crates from crates.io no longer work.');
+      }
+
+      // Vendor a temporary package that depends on on the crates to fetch them.
+      const tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), 'node-crates-'));
+      try {
+        const manifest = {
+          package: { name: 'placeholder_crates', version: '0.0.0', edition: '2021' },
+          dependencies: Object.fromEntries(ctx.placeholderCrates.map(({ name, version }) => (
+            [name, { version: `=${version}`, 'default-features': false }]
+          )))
+        };
+        await fs.writeFile(path.join(tmpDir, 'Cargo.toml'), TOML.stringify(manifest));
+        await fs.mkdir(path.join(tmpDir, 'src'));
+        await fs.writeFile(path.join(tmpDir, 'src/lib.rs'), '');
+        const vendorDir = path.join(tmpDir, 'vendor');
+        await forceRunAsync(ctx.cargo, ['vendor', '--quiet', '--versioned-dirs', vendorDir], {
+          ignoreFailure: false,
+          spawnArgs: { cwd: tmpDir }
+        });
+
+        for (const { dir, name, version } of ctx.placeholderCrates) {
+          const dest = path.join(nodeVendor, dir);
+          await fs.cp(path.join(vendorDir, `${name}-${version}`), dest, { recursive: true });
+          await fs.writeFile(path.join(dest, '.cargo-checksum.json'), '{"files":{}}\n');
+          const crate = TOML.parse(await fs.readFile(path.join(dest, 'Cargo.toml'), 'utf8'));
+          if (crate.package['rust-version']) {
+            ctx.rustVersions.push(crate.package['rust-version']);
+          }
+        }
+      } finally {
+        await removeDirectory(tmpDir);
+      }
+    }
+  };
+}
+
 function buildManifest() {
   return {
     title: 'Build new manifest',
     task: async(ctx) => {
+      if (ctx.rustVersions.length) {
+        const msrv = ctx.rustVersions.map(semver.coerce)
+          .reduce((a, b) => (semver.gt(a, b) ? a : b));
+        ctx.msrv = `${msrv.major}.${msrv.minor}`;
+      }
+
       const sourceManifest = TOML.parse(
         await fs.readFile(path.join(ctx.nodeDir, chromiumCratesDir, 'Cargo.toml'), 'utf8')
       );