On a clean ubuntu 20.04 installation I installed the Swift compiler, Visual Studio Code, downloaded the sourcekit-lsp and installed the plugin I build from it into Visual Studio Code.
Swift version 5.2.4 (swift-5.2.4-RELEASE) Target: x86_64-unknown-linux-gnu
Everything seems to work as expected, except for classes that are in different files, which are not recognized within VSCode:
use of unresolved identifier 'Calculator'
However, when building and running the application, everything is fine and works as expected.
Multiple people in the past seem to have had the same issue, but I have so far been unable to find any answer to how I might resolve the issue.