Satisfies operator affects type inference for Symbol

[yoshi-pi]

🔎 Search Terms

"Symbol", "satisfies", "type inference"

🕗 Version & Regression Information

• This changed between versions v4.9 and latest

⏯ Playground Link

https://www.typescriptlang.org/play/?#code/MYewdgzgLgBAZiEMC8MDKBPAtgIxAGwAoBKAbhgHoKYAVACwFMYoMAHJkOeRGASwmZsGnbiABQoSLBwBDAE4p02PEWIwIMqPzi8GAiMoLkqtRoPYwRshf3WH8QA

💻 Code

const foo = Symbol(); // The type of foo is typeof foo
const bar = Symbol() satisfies symbol; // The type of bar is symbol

🙁 Actual behavior

Using the satisfies operator with Symbol changes the type of bar to symbol, instead of typeof foo.

🙂 Expected behavior

I expected the satisfies operator to have no effect on type inference, so bar should have the type typeof bar.

Additional information about the issue

No response

[RyanCavanaugh]

I'm trying to figure out why you would ever write this code in the first place. Is there a more realistic repro?

[Andarist]

Since I created a PR to "fix" this - I also don't see why one would like to write this but it looks like satisfies is changing the type of its operand here and that's something that satisfies, on principle, shouldn't do. So I just decided to open a PR for this since it was a one-line change anyway.

[yoshi-pi]

I simply discovered this problem and was curious to know whether it's a bug or intentional, so I opened an issue.