Bun TypeScript 5 Decorators not working

[angelhdzdev]

I've been using bun to run src/main.ts for months. I've been working on that file to test different ideas with typescript decorators for backend.

TypeScript experimental decorators, and the new v5 decorators worked.

Today, I worked in the same file, but completely new code.

Just a class with class and method decorators.

The 2nd parameter of the class method decorator is the ClassMethodDecoratorContext in the v5 decorators.
I was console.log( ctx.name ) and it returned undefined and I was confused.

So I console.log( ctx ) and it returned "signIn", the name of the AuthController class method.
So I console.log( target ) and instead of being a function, as in the new decorators, it returns the whole class as in the old decorators!!!

I checked the tsconfig, and i dont have any option for the experimental decorators.

Then I ran bunx tsx src/main.ts and it works as expected, so tsx package is respecting the tsconfig.

typescript 5.7.2, bun 1.1.43.

So either bun is not reading my tsconfig.json, or it's using the experimental decorators by default if it's not explicitly defined.

What changed!?

[angelhdzdev]

No idea what happened. I moved to a new computer. Upgraded bun and typescript to latest.

Tried same code. Now it works.

[angelhdzdev]

Reopening

It's so strange. Even forcing bun to read my tsconfig.json using --tsconfig flag, it's using the experimental decorators.
I even set experimentalDecorators: false and that doesn't nothing.

But again, tsx is handling this well.

This must be a bug.

Code:

function classDecorator() {
  return (target: any, ctx: ClassDecoratorContext) => {
    console.log({target, ctx})
  }
}

function methodDecorator() {
  return (target: any, ctx: ClassMethodDecoratorContext) => {
    console.log({target, ctx})
  }
}


function fieldDecorator() {
  return (target: any, ctx: ClassFieldDecoratorContext) => {
    console.log({target, ctx})
  }
}


@classDecorator()
class MyClass {
  @fieldDecorator()
  myField!: string

  @methodDecorator()
  myMethod() {

  }
}

With bun:

{
  target: MyClass {
    myMethod: [Function: myMethod],
  },
  ctx: "myField",
}
{
  target: MyClass {
    myMethod: [Function: myMethod],
  },
  ctx: "myMethod",
}
{
  target: [class MyClass],
  ctx: undefined,
}

With tsx:

{
  target: [Function: myMethod],
  ctx: {
    kind: 'method',
    name: 'myMethod',
    metadata: [Object: null prototype] {},
    addInitializer: [Function: addInitializer],
    static: false,
    private: false,
    access: { has: [Function (anonymous)], get: [Function (anonymous)] }
  }
}
{
  target: undefined,
  ctx: {
    kind: 'field',
    name: 'myField',
    metadata: [Object: null prototype] {},
    addInitializer: [Function: addInitializer],
    static: false,
    private: false,
    access: {
      has: [Function (anonymous)],
      get: [Function (anonymous)],
      set: [Function (anonymous)]
    }
  }
}
{
  target: [class MyClass],
  ctx: {
    kind: 'class',
    name: 'MyClass',
    metadata: [Object: null prototype] {},
    addInitializer: [Function: addInitializer]
  }
}