[Sonata]

I'm glad people are working on this problem. Typescript's compiler performance is certainly a weakness.

Other commenters have rightly called out the complexity of the type system as the reason why this is difficult. The other reason is that Typescript does not have a formal specification. The tsc compiler is the only reference for the correct behaviour. It would be great if the official compiler and these reimplementations could share a common test suite to ensure compatibility.

[hurflmurfl]

I suppose picking top X open source Typescript codebases and compiling them with the expectation of output being identical with TSC would be one way to test this, albeit not what one would expect as a test suite.

[8n4vidtmkvmk]

they can. thats exactly what the swc guy is doing. reusing the tsc tests