From 846bd094d2d3f9725b2e87e574a70221264f8697 Mon Sep 17 00:00:00 2001
From: bluwy <bjornlu.dev@gmail.com>
Date: Wed, 12 Jul 2023 16:33:59 +0800
Subject: [PATCH 1/2] fix(esbuild): enable experimentalDecorators by default

---
 packages/vite/src/node/plugins/esbuild.ts            |  8 ++++++++
 .../tsconfig-json/__tests__/tsconfig-json.spec.ts    | 12 ++++++++++++
 playground/tsconfig-json/src/decorator.ts            |  8 ++++++++
 3 files changed, 28 insertions(+)
 create mode 100644 playground/tsconfig-json/src/decorator.ts

diff --git a/packages/vite/src/node/plugins/esbuild.ts b/packages/vite/src/node/plugins/esbuild.ts
index fedb39d9d844a1..128d14f6ce1cd0 100644
--- a/packages/vite/src/node/plugins/esbuild.ts
+++ b/packages/vite/src/node/plugins/esbuild.ts
@@ -142,6 +142,14 @@ export async function transformWithEsbuild(
       compilerOptions.useDefineForClassFields = false
     }
 
+    // esbuild v0.18 only transforms decorators when `experimentalDecorators` is set to `true`.
+    // To preserve compat with the esbuild breaking change, we set `experimentalDecorators` to
+    // `true` by default if it's unset.
+    // TODO: Remove this in Vite 5
+    if (compilerOptions.experimentalDecorators === undefined) {
+      compilerOptions.experimentalDecorators = true
+    }
+
     // esbuild uses tsconfig fields when both the normal options and tsconfig was set
     // but we want to prioritize the normal options
     if (options) {
diff --git a/playground/tsconfig-json/__tests__/tsconfig-json.spec.ts b/playground/tsconfig-json/__tests__/tsconfig-json.spec.ts
index a5e2dd47d191cd..dd130a65291001 100644
--- a/playground/tsconfig-json/__tests__/tsconfig-json.spec.ts
+++ b/playground/tsconfig-json/__tests__/tsconfig-json.spec.ts
@@ -67,4 +67,16 @@ describe('transformWithEsbuild', () => {
       'import { MainTypeOnlyClass } from "./not-used-type";',
     )
   })
+
+  test('experimentalDecorators', async () => {
+    const main = path.resolve(__dirname, '../src/decorator.ts')
+    const mainContent = fs.readFileSync(main, 'utf-8')
+    // Should not error when transpiling decorators
+    // TODO: In Vite 5, this should require setting `tsconfigRaw.experimentalDecorators`
+    // or via the closest `tsconfig.json`
+    const result = await transformWithEsbuild(mainContent, main, {
+      target: 'es2020',
+    })
+    expect(result.code).toContain('__decorateClass')
+  })
 })
diff --git a/playground/tsconfig-json/src/decorator.ts b/playground/tsconfig-json/src/decorator.ts
new file mode 100644
index 00000000000000..27a5027cb23f17
--- /dev/null
+++ b/playground/tsconfig-json/src/decorator.ts
@@ -0,0 +1,8 @@
+function first() {
+  return function (...args: any[]) {}
+}
+
+export class Foo {
+  @first()
+  method() {}
+}

From cbb24c4ead343583c142ad8a6c806701fcab0e93 Mon Sep 17 00:00:00 2001
From: bluwy <bjornlu.dev@gmail.com>
Date: Thu, 13 Jul 2023 14:08:34 +0800
Subject: [PATCH 2/2] fix: enable experimentalDecorators during scan

---
 packages/vite/src/node/optimizer/scan.ts  | 17 +++++++++++++++--
 playground/tsconfig-json/src/decorator.ts |  5 ++++-
 playground/tsconfig-json/src/main.ts      |  1 +
 3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/packages/vite/src/node/optimizer/scan.ts b/packages/vite/src/node/optimizer/scan.ts
index 3c592cec499de5..c762b6b584cf8f 100644
--- a/packages/vite/src/node/optimizer/scan.ts
+++ b/packages/vite/src/node/optimizer/scan.ts
@@ -205,8 +205,11 @@ async function prepareEsbuildScanner(
 
   const plugin = esbuildScanPlugin(config, container, deps, missing, entries)
 
-  const { plugins = [], ...esbuildOptions } =
-    config.optimizeDeps?.esbuildOptions ?? {}
+  const {
+    plugins = [],
+    tsconfigRaw,
+    ...esbuildOptions
+  } = config.optimizeDeps?.esbuildOptions ?? {}
 
   return await esbuild.context({
     absWorkingDir: process.cwd(),
@@ -219,6 +222,16 @@ async function prepareEsbuildScanner(
     format: 'esm',
     logLevel: 'silent',
     plugins: [...plugins, plugin],
+    tsconfigRaw:
+      typeof tsconfigRaw === 'string'
+        ? tsconfigRaw
+        : {
+            ...tsconfigRaw,
+            compilerOptions: {
+              experimentalDecorators: true,
+              ...tsconfigRaw?.compilerOptions,
+            },
+          },
     ...esbuildOptions,
   })
 }
diff --git a/playground/tsconfig-json/src/decorator.ts b/playground/tsconfig-json/src/decorator.ts
index 27a5027cb23f17..2dc056ec09c809 100644
--- a/playground/tsconfig-json/src/decorator.ts
+++ b/playground/tsconfig-json/src/decorator.ts
@@ -4,5 +4,8 @@ function first() {
 
 export class Foo {
   @first()
-  method() {}
+  // @ts-expect-error we intentionally not enable `experimentalDecorators` to test esbuild compat
+  method(@first test: string) {
+    return test
+  }
 }
diff --git a/playground/tsconfig-json/src/main.ts b/playground/tsconfig-json/src/main.ts
index 6ae1fe03b7d023..bec5c6bcc2729d 100644
--- a/playground/tsconfig-json/src/main.ts
+++ b/playground/tsconfig-json/src/main.ts
@@ -1,6 +1,7 @@
 // @ts-nocheck
 import '../nested/main'
 import '../nested-with-extends/main'
+import './decorator'
 
 // eslint-disable-next-line @typescript-eslint/consistent-type-imports
 import { MainTypeOnlyClass } from './not-used-type'