From 9330c1a1183723638b3c83cff63ec6f18a09294c Mon Sep 17 00:00:00 2001
From: dsyddall <danielsyddall@gmail.com>
Date: Tue, 14 Nov 2023 12:02:29 +0000
Subject: [PATCH] fix(core): respect useDefineForClassFields tsconfig value
 (#740)

---
 packages/core/index.ts                             |  2 ++
 .../ts-compiler-options-to-swc-config.spec.ts      |  2 ++
 packages/register/read-default-tsconfig.ts         | 14 ++++++++++++--
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/packages/core/index.ts b/packages/core/index.ts
index a7f50b111..c79573ea5 100644
--- a/packages/core/index.ts
+++ b/packages/core/index.ts
@@ -17,6 +17,7 @@ export interface Options {
   jsx?: boolean
   experimentalDecorators?: boolean
   emitDecoratorMetadata?: boolean
+  useDefineForClassFields?: boolean
   dynamicImport?: boolean
   esModuleInterop?: boolean
   keepClassNames?: boolean
@@ -49,6 +50,7 @@ function transformOption(path: string, options?: Options, jest = false): SwcOpti
           transform: {
             legacyDecorator: Boolean(opts.experimentalDecorators),
             decoratorMetadata: Boolean(opts.emitDecoratorMetadata),
+            useDefineForClassFields: Boolean(opts.useDefineForClassFields),
             react: options?.react,
             // @ts-expect-error
             hidden: {
diff --git a/packages/register/__test__/ts-compiler-options-to-swc-config.spec.ts b/packages/register/__test__/ts-compiler-options-to-swc-config.spec.ts
index fea7b875e..f220c87cb 100644
--- a/packages/register/__test__/ts-compiler-options-to-swc-config.spec.ts
+++ b/packages/register/__test__/ts-compiler-options-to-swc-config.spec.ts
@@ -15,6 +15,7 @@ test('default values', (t) => {
     sourcemap: false,
     experimentalDecorators: false,
     emitDecoratorMetadata: false,
+    useDefineForClassFields: false,
     esModuleInterop: false,
     dynamicImport: true,
     externalHelpers: false,
@@ -99,6 +100,7 @@ test('should set all values', (t) => {
     target: 'es5',
     experimentalDecorators: options.experimentalDecorators,
     emitDecoratorMetadata: options.emitDecoratorMetadata,
+    useDefineForClassFields: false,
     esModuleInterop: options.esModuleInterop,
     externalHelpers: true,
     dynamicImport: true,
diff --git a/packages/register/read-default-tsconfig.ts b/packages/register/read-default-tsconfig.ts
index 9f98cf1b8..6e6b56da9 100644
--- a/packages/register/read-default-tsconfig.ts
+++ b/packages/register/read-default-tsconfig.ts
@@ -97,21 +97,31 @@ function toModule(moduleKind: ts.ModuleKind) {
   }
 }
 
+/**
+ * The default value for useDefineForClassFields depends on the emit target
+ * @see https://www.typescriptlang.org/tsconfig#useDefineForClassFields
+ */
+function getUseDefineForClassFields(compilerOptions: ts.CompilerOptions, target: ts.ScriptTarget): boolean {
+  return compilerOptions.useDefineForClassFields ?? target >= ts.ScriptTarget.ES2022
+}
+
 export function tsCompilerOptionsToSwcConfig(options: ts.CompilerOptions, filename: string): Options {
   const isJsx = filename.endsWith('.tsx') || filename.endsWith('.jsx') || Boolean(options.jsx)
+  const target = options.target ?? ts.ScriptTarget.ES2018
   return {
     module: toModule(options.module ?? ts.ModuleKind.ES2015),
-    target: toTsTarget(options.target ?? ts.ScriptTarget.ES2018),
+    target: toTsTarget(target),
     jsx: isJsx,
     sourcemap: options.sourceMap && options.inlineSourceMap ? 'inline' : Boolean(options.sourceMap),
     experimentalDecorators: options.experimentalDecorators ?? false,
     emitDecoratorMetadata: options.emitDecoratorMetadata ?? false,
+    useDefineForClassFields: getUseDefineForClassFields(options, target),
     esModuleInterop: options.esModuleInterop ?? false,
     dynamicImport: true,
     keepClassNames: true,
     externalHelpers: Boolean(options.importHelpers),
     react:
-      options.jsxFactory || options.jsxFragmentFactory || options.jsx || options.jsxImportSource
+      options.jsxFactory ?? options.jsxFragmentFactory ?? options.jsx ?? options.jsxImportSource
         ? {
             pragma: options.jsxFactory,
             pragmaFrag: options.jsxFragmentFactory,