Treatment of recursive tuples that utilize type spread.

TypeScript Version: 4.0.2

Search Terms: spread tuple in recursive tuple type

Code

I'm trying to model a type that could evaluate to any of the following:

["list", "of", "Post"];
["list", "of", "list", "of", "Post"];
["list", "of", "list", "of", "list", "of", "Post"];
// ... could go on

The following approach produces a circularity error, even though tuple types are circularity-capable since 3.7 :/

type Nested = ["list", "of", ...(["Post"] | Nested)];

Expected behavior:

To be able to type-check the following (for example):

const nested: Nested = ["list", "of", "list", "of", "Post"];

Actual behavior:

Circularity error.

Any help would be greatly appreciated! Thank you!

No source file or test is named. Start by reproducing the circularity error with the provided TypeScript 4.0.2 recursive tuple example, then trace the type-checker handling for recursive tuple types and type spreads. Done means the sample declaration and nested value type-check without the circularity error, with coverage added in the appropriate compiler test area.