feat(49385): Inlay hint for type of literal-initialized constant is unnecessary

[a-tarasyuk]

Fixes #49385

[a-tarasyuk]

@DanielRosenwasser Is this the expected behavior for this feature? Or do we need to omit variables with type declarations completely?

[DanielRosenwasser]

Or do we need to omit variables with type declarations completely?

Can you give an example?

[a-tarasyuk]

@DanielRosenwasser I meant the following case

interface Foo {
  a: number;
}
const a /* : Foo */ = { a: 1 }
        ^^^^^^^^^ - is it acceptable to have a hint here?

[DanielRosenwasser]

Hah, now we've got some more subtlety.

I would say no - first we shouldn't provide try to provide hints using structurally identical types. But for basic object types, my experience would be that that sort of hint stops being useful pretty quickly.

I guess this comes down to a few heuristics on "obvious" forms you should omit on for variables and parameter declarations

• A const initialized to a primitive literal.

  const foo = "...";

• A binding initialized with a type assertion

  const foo = { /*...*/} as SomeType;
  const bar = <SomeType>{ /*...*/};
  const baz = {/*...*/} as const;

• A binding initialized with a new expression where the instance type name and the constructor name are identical.

  class Foo {}
  namespace asd { export class Foo {} }
  const foo = new Foo();
  const foo = new asd.Foo();

• An object literal

  const foo = { a: 123, b: 456 };

@andrewbranch, @gabritto, and @jakebailey might have some thoughts.

[jakebailey]

I think those exceptions are all reasonable to my eye.