Set swc option keepClassNames whenever possible

package.json

@@ -112,8 +112,8 @@
   },
   "devDependencies": {
     "@microsoft/api-extractor": "^7.15.2",
-    "@swc/core": ">=1.2.45",
-    "@swc/wasm": ">=1.2.45",
+    "@swc/core": ">=1.2.50",
+    "@swc/wasm": ">=1.2.50",
     "@types/chai": "^4.0.4",
     "@types/diff": "^4.0.2",
     "@types/lodash": "^4.14.151",
@@ -143,8 +143,8 @@
     "util.promisify": "^1.0.1"
   },
   "peerDependencies": {
-    "@swc/core": ">=1.2.45",
-    "@swc/wasm": ">=1.2.45",
+    "@swc/core": ">=1.2.50",
+    "@swc/wasm": ">=1.2.50",
     "@types/node": "*",
     "typescript": ">=2.7"
   },

src/test/index.spec.ts

@@ -345,15 +345,15 @@ test.suite('ts-node', (test) => {
         `${cmdNoProject} --transpiler ts-node/transpilers/swc-experimental transpile-only-swc`
       );
       expect(err).to.equal(null);
-      expect(stdout).to.contain('hello world');
+      expect(stdout).to.contain('Hello World!');
     });
 
     test('should support third-party transpilers via tsconfig', async () => {
       const { err, stdout } = await exec(
         `${cmdNoProject} transpile-only-swc-via-tsconfig`
       );
       expect(err).to.equal(null);
-      expect(stdout).to.contain('hello world');
+      expect(stdout).to.contain('Hello World!');
     });
 
     test('should pipe into `ts-node` and evaluate', async () => {

src/transpilers/swc.ts

@@ -55,6 +55,8 @@ export function create(createOptions: SwcTranspilerOptions): Transpiler {
   const nonTsxOptions = createSwcOptions(false);
   const tsxOptions = createSwcOptions(true);
   function createSwcOptions(isTsx: boolean): swcTypes.Options {
+    const swcTarget = targetMapping.get(target!) ?? 'es3';
+    const keepClassNames = target! >= /* ts.ScriptTarget.ES2016 */ 3;
     return {
       sourceMaps: sourceMap,
       // isModule: true,
@@ -71,7 +73,7 @@ export function create(createOptions: SwcTranspilerOptions): Transpiler {
           decorators: experimentalDecorators,
           dynamicImport: true,
         },
-        target: targetMapping.get(target!) ?? 'es3',
+        target: swcTarget,
         transform: {
           decoratorMetadata: emitDecoratorMetadata,
           legacyDecorator: true,
@@ -81,9 +83,10 @@ export function create(createOptions: SwcTranspilerOptions): Transpiler {
             useBuiltins: false,
             pragma: jsxFactory!,
             pragmaFrag: jsxFragmentFactory!,
-          },
+          } as swcTypes.ReactConfig,
         },
-      },
+        keepClassNames,
+      } as swcTypes.JscConfig,
     };
   }
 

tests/transpile-only-swc-via-tsconfig/index.ts

@@ -1,4 +1,9 @@
+// Test for #1343
+const Decorator = function () {};
+@Decorator
+class World {}
+
 // intentional type errors to check transpile-only ESM loader skips type checking
 parseInt(1101, 2);
-const x: number = 'hello world';
+const x: number = `Hello ${World.name}!`;
 console.log(x);

tests/transpile-only-swc-via-tsconfig/tsconfig.json

@@ -4,8 +4,10 @@
     "transpiler": "ts-node/transpilers/swc-experimental"
   },
   "compilerOptions": {
+    "target": "ES2018",
     "module": "ESNext",
     "allowJs": true,
-    "jsx": "react"
+    "jsx": "react",
+    "experimentalDecorators": true
   }
 }

tests/transpile-only-swc/index.ts

@@ -1,4 +1,9 @@
+// Test for #1343
+const Decorator = function () {};
+@Decorator
+class World {}
+
 // intentional type errors to check transpile-only ESM loader skips type checking
 parseInt(1101, 2);
-const x: number = 'hello world';
+const x: number = `Hello ${World.name}!`;
 console.log(x);

tests/transpile-only-swc/tsconfig.json

@@ -1,7 +1,9 @@
 {
   "compilerOptions": {
+    "target": "ES2018",
     "module": "ESNext",
     "allowJs": true,
-    "jsx": "react"
+    "jsx": "react",
+    "experimentalDecorators": true
   }
 }