Feature Idea: How far can we take Pyrefly's type inference?

[michaelfortunato]

Is it possible for Pyrefly to see that x must be an int in the second if block as the two predicates are the same and its dependency b has not changed?

x: int | None = None
b = "foo"
if b == "bar":
   x = 3
if b == "bar":
    # is it possible to infer that x MUST be 3 here? 
    reveal_type(x)

https://pyrefly.org/sandbox/?code=MQAg6gpgNgxg9gWwiALnVALZAFAngJwgDMpcQBlAQwDsATAIzgA8AaTASwGcQuRKQADpQDmEAFCgA7lkIhccAK4gYNEJPzsUENpwyVZNWiCgR91PowUpUuAe2rCe5vCgxxqAOgkSQACQgGBsqKAiYgRKYoCoTccEQc3JyGjEwAXD4AtCAA4hDWhJRQGSjsSDYCyDBYMADW9o4REAyUtZkgAKqcyIQAbqZQAPoothAAFACUqOj2nBUw1vYR%2BIRGwxWcbRBMFRpI1NaSmhiYyACSACIAouGR0RDcrpQHyJwKAgJw%2BNajEB7CHnwrHB4AhQnltCBhHBitDaMR7Jp2O42G4%2Bvg2HkYOM2mANFo%2BHQQPgFM5cK53ME4SBaOxCPNSE45Ip8CB6Pg4JIuvgxGIiOyEOV6jxQZ9rAAqMRpJzWAA%2BIAAcu5kABeBVKsT0ECqgBERDgcG1YnY8U1yp19H02vSIBtTC1IAAzEaTVrzZbrTaQKBeJpBHBOJx2PQwmgnEtME8QHaALLtcgAFVZyAdIBkEAA-CAxJ6iRA%2BoUhiNRkxsaBev1CxU1OwoFBBOzaAoYMh%2BGtkAF2SzHtYtLXuPIlK5kG2QHhCCQyHoNqAQQIrE1wp8TrmovhzKN7AllJQujoUPhsUA&version=3.12

[rchen152]

I believe the fact that pyrefly doesn't narrow here is a bug - if I tweak the example to https://pyrefly.org/sandbox/?code=GYJw9gtgBALgngBwJYDsDmUkQWEMogCmAboQIYA2A%2BvAoQFAAeAXJivgD5QByYKhUALw8%2BDACaFgUYAAoAlM3pRlUAEZCoAImBgwmpSqRT1g4ZtVkQmxSttRGGgMwHlRtULMWrNu8oDEmADOmPg4gYFIqhQCMGBswIQgsAAWZPgOALIAqgDKACpqAo5QyYmEAPxQLnZEpJQ0iIQyjHJAA&version=3.12, then pyrefly reveals Literal[3].

[rchen152]

Closing this discussion in favor of newly opened #997.