Hex Colors error with TS2590: Expression produces a union type that is too complex to represent

[AtomicGamer9523]

🔎 Search Terms

ts(2590), Expression produces a union type that is too complex to represent., HexTypes

🕗 Version & Regression Information

This is an error that typescript throws when I try to build it, as well as the LSP complains. It raises the error ts(2590), Expression produces a union type that is too complex to represent

⏯ Playground Link

https://www.typescriptlang.org/play/?#code/C4TwDgpgBAEhAeBhAFgQwE5QLxQEQAZcoAfPARiNNwCZK8BmO3AFiYFYmA2JgdiYA4mATiYBBJgCEmiJgBEmAUSYAxXAG4AUKEiwE9RAHsANgcw4ABgGIAJAG84SNOgC+dhygyv7CDy-ObtaAdOQxMzKCs3Hycvdxiox08E31jopO9EvwDwIIR+UNNsCJsMlOT40oq49OqXcpq0usrPfw0NBDBTYChA3SRjQpwHfQHMUmCCsb780bUgA

💻 Code

type HexChar = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" | "A" | "B" | "C" | "D" | "E" | "F";
type Hex3Color = `#${HexChar}${HexChar}${HexChar}`;
type Hex6Color = `#${HexChar}${HexChar}${HexChar}${HexChar}${HexChar}${HexChar}`;
type Hex8Color = `#${HexChar}${HexChar}${HexChar}${HexChar}${HexChar}${HexChar}${HexChar}${HexChar}`;

export type HexColor = Hex3Color | Hex6Color | Hex8Color;

🙁 Actual behavior

The type of HexColor should be well defined and accessible. As well as there shouldn't be any errors.

🙂 Expected behavior

The type of HexColor is any, and there are errors.

Additional information about the issue

It seems that also Deno is affected (I first discovered it using Deno). I tried switching to plain TS, still raises errors.

[AtomicGamer9523]

It seems that the maximum states that union can represent is 2^32, but Hex6Color and Hex8Color are more than that. The simple fix would be to change the max number of union states from a 32-bit integer to a 64-bit integer. I am just not quite sure where that error actually gets raised

[MartinJohns]

Duplicate of #43388.

It seems that the maximum states that union can represent is 2^32

The limit is 25, and that's intentional.

[AtomicGamer9523]

It seems that the maximum states that union can represent is 2^32

The limit is 25, and that's intentional.

I searched for 25, and can't seem to find where this limitation actually is. Is it possible to submit a PR to increase that value ?

[jcalz]

25 is from #30779 but that doesn't seem to be related to this. The limit here is on the order of 10^5, and if you are trying to write a union bigger than that then you're doing something TS doesn't want you to do. The limit is there for performance so I'm sure they're not going to increase it to some large number just because the number can be represented easily.

[RyanCavanaugh]

The limit is in place to stop your typechecking from taking six hours, not because we don't have access to 31 bits worth of integer 😉

[AtomicGamer9523]

I see, thank you. In my case the only thing I can really do then is to perform some analysis during compile time, and/or hope for #43335 to be accepted

[typescript-bot]

This issue has been marked as "Duplicate" and has seen no recent activity. It has been automatically closed for house-keeping purposes.