microsoft / microsoft/TypeScript
Generic Tuple Optional Parameter spread errors with Type instantiation is excessively deep and possibly infinite. ts(2589)
まだ誰も着手していません。
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説明
Bug Report
type StringableParameters<TArgs>
= TArgs extends [optionalHead?:(infer OptionalArg), ...optionalRest:infer OptionalRest] //optionalHead? <- this question mark is what's causing error
? [(OptionalArg|string)?, ...StringableParameters<OptionalRest>] //ts(2589)
: []
type Test = StringableParameters<[1,2?,3?]>
// type Test = [(string | 1)?, (string | 2)?, (string | 3)?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, any?, ...any[]]
That question mark TArgs extends [optionalHead?:(infer OptionalArg) allowing parameters to be optional is leading to the infinite nesting with ts2589 error. If I remove that question mark - it compiles, but omit the optional parameters of the tuple
type StringableParameters<TArgs> = TArgs extends [optionalHead:(infer OptionalArg), ...optionalRest:infer OptionalRest]
? [(OptionalArg|string), ...StringableParameters<OptionalRest>]
: []
type Test = StringableParameters<[1, 2?, 3?]>
//type Test = [string | 1] - optional parameters omitted
🔎 Search Terms
Type instantiation is excessively deep and possibly infinite. ts(2589)
Generic Tuple extends Optional argument
🕗 Version & Regression Information
Typescript v5, v4.7.4,...
⏯ Playground Link
Playground link with relevant code
💻 Code
type StringableParameters<TArgs>
= TArgs extends [optionalHead?:(infer OptionalArg), ...optionalRest:infer OptionalRest] //optionalHead? <- this question mark is what's causing error
? [(OptionalArg|string)?, ...StringableParameters<OptionalRest>] //ts(2589)
: []
type TestOptional = StringableParameters<[1,2?,3?]>
/* type TestOptional = [(string | 1 | undefined)?, (string | 2 | undefined)?, (string | 3 | undefined)?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?,
unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?,
unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?,
unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, unknown?, ... 6 more ...?, any?]
*/
type StringableParametersNoOptional<TArgs>
= TArgs extends [optionalHead:(infer OptionalArg), ...optionalRest:infer OptionalRest] //optionalHead? <- this question mark is what's causing error
? [(OptionalArg|string), ...StringableParametersNoOptional<OptionalRest>] //ts(2589)
: []
type TestNoOptional = StringableParametersNoOptional<[1,2?,3?]>
//type TestNoOptional = [string | 1]
🙁 Actual behavior
Type instantiation is excessively deep and possibly infinite.(2589) and if I use ts-ignore, the TestOptional type has excessive amount of unknown optional parameters on the tail
🙂 Expected behavior
type TestOptional = [(string | 1 | undefined)?, (string | 2 | undefined)?, (string | 3 | undefined)?]
コントリビューションガイド
はじめの一歩
- issue を最後まで読み、次にプロジェクトのコントリビューションガイドを読みます。
- 着手することを issue にコメントします — 二人が同じ作業をするのを防げます。
- リポジトリをフォークし、ブランチを切って変更します。
- issue 番号を参照したプルリクエストを送ります。
調査の方向性
リンクされた TypeScript Playground の再現コードから始め、issue に示された optional および non-optional の tuple conditional types を比較してください。optional spread がなぜ過剰な unknown パラメーターへ再帰するのかを調査してください。完了の条件は、ts(2589) なしで期待される3要素の optional tuple が生成されることです。
索引モデルが issue の本文から書いたものです。
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