Auto-synthesize getter and setter at different access levels

[bbrk24]

C# allows you to automatically synthesize a getter and a setter for a hidden field with different access levels:

class Foo
{
    public int X { get; private set; }
}

class Foo has three declarations:

• A hidden private field with a name generated by the compiler
• A synthesized public getter for X that returns the value of the hidden private field
• A synthesized private setter for X that modifies the value of the hidden field

Swift has a different syntax for the same concept:

class Foo {
  public private(set) var x: Int
}

Civet could make use of the same thing:

class Foo
  private set x: number
// vvv
class Foo {
  #x: number;
  get x(): number { return this.#x; }
  private set x(value: number) { this.#x = value; }
}

I'm open to suggestions on the syntax; it doesn't have to be private set NAME: TYPE. TypeScript does not have a way to indicate that a field should be readonly at one access level but not another, but it does allow the getter and setter to have different access levels as in the above code.

The private field would have to have a synthesized name such that even if the class had an unrelated #x, this would not conflict.