Syntax overlap with proposal-shorthand-improvements

[rbuckton]

I presented on https://github.com/rbuckton/proposal-shorthand-improvements several years ago and while it did not advance to Stage 1, I intend to bring it back to committee in the near future with some amendments. My concern is that there is significant syntactic overlap between the two proposals which could be confusing should both be adopted:

this proposal:

const state2 = #{
  ...state1,
  counters[0].value: 2, // sets `state2.counters[0].value` to `2`
  metadata.lastUpdate: 1584383011300, // sets `state2.metadata.lastUpdate` to `1584383011300`
};

proposal-shorthand-improvements:

const counters = [{ value: 2 }];
const metadata = { lastUpdate: 1584383011300 };
const state2 = {
  ...state1,
  counters[0].value, // sets `state2.value` to `counters[0].value`
  metadata.lastUpdate // sets state2.lastUpdate` to `metadata.lastUpdate`
}

The proposal was not adopted due to some syntactic concerns that I intend to address, however the proposal has been on the backburner while I focused on advancing other proposals. Also note that my proposal is based on existing prior art in C#:

var x = new { y = 1 };
var obj = new { x.y };
Console.WriteLine(obj.y); // 1