From c13bfc75fb832709f921652575ee3c2f57a91a87 Mon Sep 17 00:00:00 2001
From: fisker Cheung <lionkay@gmail.com>
Date: Thu, 30 Jan 2025 20:22:09 +0800
Subject: [PATCH] Support read config from `package.json` with JSONC syntax on
 Bun (#17041)

---
 changelog_unreleased/api/17041.md     | 22 ++++++++++++++++
 src/config/prettier-config/loaders.js | 36 +++++++++++++++++++++------
 2 files changed, 50 insertions(+), 8 deletions(-)
 create mode 100644 changelog_unreleased/api/17041.md

diff --git a/changelog_unreleased/api/17041.md b/changelog_unreleased/api/17041.md
new file mode 100644
index 000000000..dfeddafed
--- /dev/null
+++ b/changelog_unreleased/api/17041.md
@@ -0,0 +1,22 @@
+#### Support read config from `package.json` with JSONC syntax on Bun (#17041 by @fisker)
+
+[Bun 1.2 added JSONC support in `package.json`](https://bun.sh/blog/bun-v1.2#jsonc-support-in-package-json), in previous version of Prettier, it will ignore `prettier` config in it. Since Prettier main, we can read `prettier` config from it without error.
+
+However, since it's just a Bun feature and not supported by Node.js, it can only work when running Prettier with Bun.
+
+Important note: Prettier uses [`json-stringify` parser](https://prettier.io/docs/en/options#parser) to format `package.json` file by default, to support formatting `package.json` file with JSONC syntax, you need override the parser option
+
+```js
+export default {
+  overrides: [
+    {
+      files: ["package.json"],
+      options: {
+        parser: "jsonc",
+      },
+    },
+  ],
+};
+```
+
+If you can't upgrade Prettier for some reason, you can still use JSONC syntax in `package.json`, but don't put your `prettier` config in it, you'll have to use another [configuration file](https://prettier.io/docs/en/configuration).
diff --git a/src/config/prettier-config/loaders.js b/src/config/prettier-config/loaders.js
index b7d3923d7..10c15fb62 100644
--- a/src/config/prettier-config/loaders.js
+++ b/src/config/prettier-config/loaders.js
@@ -15,13 +15,33 @@ async function readJson(file) {
   }
 }
 
-async function loadJs(file) {
+async function importModuleDefault(file) {
   const module = await import(pathToFileURL(file).href);
   return module.default;
 }
 
+async function readPackageJson(file) {
+  try {
+    return await readJson(file);
+  } catch (error) {
+    // TODO: Add tests for this
+    // Bun supports comments and trialing comma in `package.json`
+    // And it can load via `import()`
+    // https://bun.sh/blog/bun-v1.2#jsonc-support-in-package-json
+    if (process.versions.bun) {
+      try {
+        return await importModuleDefault(file);
+      } catch {
+        // No op
+      }
+    }
+
+    throw error;
+  }
+}
+
 async function loadConfigFromPackageJson(file) {
-  const { prettier } = await readJson(file);
+  const { prettier } = await readPackageJson(file);
   return prettier;
 }
 
@@ -60,12 +80,12 @@ const loaders = {
     }
   },
   ".json": readJson,
-  ".js": loadJs,
-  ".mjs": loadJs,
-  ".cjs": loadJs,
-  ".ts": loadJs,
-  ".mts": loadJs,
-  ".cts": loadJs,
+  ".js": importModuleDefault,
+  ".mjs": importModuleDefault,
+  ".cjs": importModuleDefault,
+  ".ts": importModuleDefault,
+  ".mts": importModuleDefault,
+  ".cts": importModuleDefault,
   ".yaml": loadYaml,
   ".yml": loadYaml,
   // No extension