random thought whether `mypy` needs to check transitive depe

Question

random thought whether `mypy` needs to check transitive dependees is dependent on whether a file exports a type and the same goes for `javac` where we actually implemented exports described in <https blog pantsbuild org automatically unlocking concurrent builds and fine grained caching on the jvm with dependency inference exporttypes|the JVM inference post>

witty-crayon-22786 · Answer

but there is some circularity involved in actually figuring out which types are exported we can do it in Java because return types and non local variables must have their types declared and so dependency inference can indicate that certain symbols get exported

witty-crayon-22786 · Answer

doing the same with mypy would involve recursively invoking mypy upward in the graph with a plugin that told you which other modules a file consumed

bitter-ability-32190 · Answer

What would be the gain

witty-crayon-22786 · Answer

if you change an implementation detail such as a method body rather than a public API like a return type or method then we would not need to `check` dependees

bitter-ability-32190 · Answer

I think wiring the mypy cache gets us a lot fo the way for perf This would be an orthogonal bonus perf

witty-crayon-22786 · Answer

yea

witty-crayon-22786 · Answer

it s primarily significant in huge repos

witty-crayon-22786 · Answer

cc < ancient vegetable 10556> since you worked on exports

bitter-ability-32190 · Answer

Seems doable assuming we could ask mypy for the info

bitter-ability-32190 · Answer

You d need to run using the users mypy PEX IMO so it d need to be supported across a wide range of versions

witty-crayon-22786 · Answer

yea tricky and actually unlike dependency inference in general getting this wrong could lead to under checking compilation

witty-crayon-22786 · Answer

i e if you fail to notice an export you don t check a dependee that you did need to check

happy-kitchen-89482 · Answer

Supporting the mypy cache and daemon might be bigger wins

hundreds-father-404 · Answer

yeah mypy is already pretty fast w o pants

bitter-ability-32190 · Answer

< hundreds father 404> that s what I said about `black`and it s cache joy cat

bitter-ability-32190 · Answer

But also yeah I think cache would be a heavy hitter In the spirit of blazing fast CI though porque no Los dos

happy-kitchen-89482 · Answer

Porque esto es complicado

bitter-ability-32190 · Answer

I think the two ideas are orthogonal enough to not complicate each other