Change Unions/Tagged Union initialization

[CrazieNewb]

Current way

const foo = Type { .Int = .{
  .signedness = .signed,
  .bits = 32,
} };

const boo: Type = .{
  .Int = .{
    .signedness = .signed,
    .bits = 32,
  }
};

Proposed way

const foo = Type.Int {       //$1
  .signedness = .signed,
  .bits = 32,
};

const boo: Type = .Int {
  .signedness = .signed,
  .bits = 32,
};

Pros:

• Easier to read
• Fits capitalization of enum's (treats them as a type)
• Fits enum initialization syntax
• Treats void type union fields as an enum

Cons:

• New special syntax
• Union field may be confused with a type ($1)

Extra:
const bar = Type.Int { ... } syntax might be confusing

const foo: Foo = .{
  .x = 5,      // Could be optional, or not
  .y = .A {5}  // Is clearly a union + tuple
  .z = .X      // is an enum or void union
};

const bar = Type.Int {   // Could be a union or type
  .signedness = .signed,
  .bits = 32,
};

[tauoverpi]

See #10710 which solves this without changes to initialization for @Type where it's currently a major pain point.

[mlugg]

Please do not file a proposal to change the language.