From e1ec1e64bb1adf9a182fccb62c4b9e664edfd366 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fran=C3=A7ois=20Daoust?= <fd@w3.org>
Date: Thu, 23 Nov 2023 14:48:49 +0100
Subject: [PATCH] Fix build when previous build steps already exist (#1137)

Before it runs a build step, the code loads the results of the previous step.
If the file exists, it also loads the previous results of the current step, for
use as fallback if some network issue occurs.

The loading was done using `require()`. The problem is that `require()`
maintains a cache of loaded modules, so if the previous results of the current
step existed, the code actually reused them for the *following* step as well.

This bug did not occur in production because the build job starts from scratch.
In particular, it does not have previous results of build steps.
---
 src/build-index.js | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/build-index.js b/src/build-index.js
index 56c1ba3b..687f34a4 100644
--- a/src/build-index.js
+++ b/src/build-index.js
@@ -373,16 +373,18 @@ async function generateIndex(specs, { step = "all", previousIndex = null, log =
 async function generateIndexFile(specsFile, targetFile, step) {
   // If the index already exists, reuse the info it contains when info cannot
   // be refreshed due to some external (network) issue.
-  const previousIndex = (function () {
+  const previousIndex = await (async function () {
     try {
-      return require(path.resolve(targetFile));
+      const json = await fs.readFile(path.resolve(targetFile), 'utf8');
+      return JSON.parse(json);
     }
     catch (err) {
       return [];
     }
   })();
 
-  const specs = require(path.resolve(specsFile));
+  const specsJson = await fs.readFile(path.resolve(specsFile));
+  const specs = JSON.parse(specsJson);
   const index = await generateIndex(specs, { previousIndex, step });
   console.log(`Write ${targetFile}...`);
   await fs.writeFile(targetFile, JSON.stringify(index, null, 2));