ImportType attributes can include JS expressions

[easrng]

🔎 Search Terms

importtype, import type parsing

🕗 Version & Regression Information

• This changed between versions 4.6.4 and 4.7.4 (with the old assert keyword)

⏯ Playground Link

https://www.typescriptlang.org/play/?ts=6.0.0-dev.20250802#code/CYUwxgNghgTiAEBbA9sArhBAiA7lALlgNwBQ+AngA4ID68AvPBdcgGbwCWilyM+AFLgJYANPADeJePCgBnWSD4AuCVOkyV-fgEoGAPlXr1YZADtZyTADoIyAOaCcAC3LwwUU-HLI08HDA58BAArWXgnRRAAfhiorG1SIwBfbR0RNSSSFNIgA

💻 Code

declare module "wat";
type _ = typeof import("wat", {
  assert: {
    a: (() => {
      console.log("why can you write js here????");
    })(),
  }
});

🙁 Actual behavior

parser accepts arbitrary JS expressions inside a type expression

🙂 Expected behavior

parser only allows string literal values or arbitrary type values

Additional information about the issue

No response

[sdotson]

I'll give it a go: #62638