use [""] in object will lose ts check

🔎 Search Terms

          This seems to be a TypeScript bug/limitation:

TypeScript Playground

Originally posted by @KermanX in https://github.com/vuejs/language-tools/issues/3819#issuecomment-2173682276

🕗 Version & Regression Information

• This is a crash
• This changed between versions ______ and _______
• This changed in commit or PR _______
• This is the behavior in every version I tried, and I reviewed the FAQ for entries about _________
• I was unable to test this on prior versions because _______

⏯ Playground Link

https://www.typescriptlang.org/play/?#code/FAYw9gdgzgLgBAQwFxwEoFNwCcAmAeWLASwgHMAaOCAVwFsAjdLAPjgDI4BvRARhR7gBfOAF4uQxFEQQAnsGAIAdAh7AA9GrgA9APwKA2gCIVhgLrrNuhcoBMF7XoRGENs3A1wAcgHk4ACQBJTwAVAEJ7KyA

💻 Code

const a: Record<string, number> & { a1: 1 } = { } as any

a.a1
// ^?
a["a1"]
// ^?
a.a2
// ^?
a["a2"] // NO HINT!
// ^?

🙁 Actual behavior

a["a2"] // NO HINT!

🙂 Expected behavior

a["a2"] should be hint by typescript

Additional information about the issue

No response

Start with the linked TypeScript Playground and reproduce the difference between a.a2 and a["a2"] using the Record<string, number> intersection shown in the issue. Trace how these two property-access forms are checked and identify why the bracket form produces no hint. Done means a["a2"] receives the expected TypeScript hint consistently with a.a2.