A modern programming language that makes developers happier.

kotlinlang

What purpose does `TowerData`, `TowerContext`,`TowerXXX` serve in type resolve stage?  Is it similar to `FirScope` and its subclasses? but is used for FunctionCall type resolving?

During resolution of one single call compiler creates so called "tower" with different scopes on each level and then processes level by level until find successful candidate(s) in some level
All (or almost all) levels are based on some scope, but bring additional semantic information, which is specific only to call resolution
E.g. scopes of implicit and explicit receiver are semantically the same, but they have different meaning for tower resolver (e.g. they have different priorities and different rules for implicit invoke resolution)

So all classes with word `Tower` in the name relates to call resolution