Intellisense doesn't narrow properly when discriminator is a template literal

[gordonmleigh]

🔎 Search Terms

"intellisense template literal", "intellisense property union"

🕗 Version & Regression Information

• This is the behavior in every version I tried (v4.9.5, v5.8.2)

⏯ Playground Link

No response

💻 Code

I didn't include a playground link since it's an intellisense issue.

type A = {
  id: `A:${string}`;
  a: number;
};

type B = {
  id: `B:${string}`;
  b: number;
};

function foo<T extends A | B>(item: T): void {}

foo({ id: "B:" /* auto-complete here */ });

🙁 Actual behavior

When you trigger intellisense, it suggests all the property names of the union, even if it could already narrow it based on what you've typed so far:

If id is a literal rather than a template literal type, the suggestions are properly narrowed.

🙂 Expected behavior

I think the property suggestions should be limited to the narrowed type, similar to if the discriminant is an ordinary string literal.

Additional information about the issue

No response