Microsoft/TypeScript

`typeChecker.getTypeArguments` returns unexpected extra type argument

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#38.391 aberto em 7 de mai. de 2020

 (1 comentário) (0 reação) (0 responsável)TypeScript (13.395 forks)batch import
BugDomain: APIHelp Wanted

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Description

TypeScript Version: 3.8.3

Search Terms: getTypeArguments

Code

Given input like

class X extends Y<string> {}

Call typeChecker.getTypeArguments(typeChecker.getTypeAtLocation(...)) on the Y<string> node.

Expected behavior: You get back one type argument (string).

Actual behavior: You get back two, string and X.

I imagine this is maybe something around how TS handles this typing internally, but as a user of the API I'm not sure I can predict when this function returns these or not.

Playground Link:

Related Issues: https://github.com/microsoft/TypeScript/issues/33693 suggests this API changed recently

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