The idea here is to unify the different ways in which we can currently set options on SourceKit-LSP in a scalable way: Environment variables, command line arguments to `sourcekit-lsp` and initialization options.
The idea is that a user can define a `~/.sourcekit-lsp/.sourcekit-lsp` file (we store logs in `~/.sourcekit-lsp/logs` on non-Darwin platforms), which will be used as the default configuration for all SourceKit-LSP instances. They can also place a `.sourcekit-lsp` file in the root of a workspace to configure SourceKit-LSP for that project specifically, eg. setting arguments that need to be passed to `swift build` for that project and which thus also need to be set on SourceKit-LSP.
For compatibility reasons, I’m mapping the existing command line options into the new options structure for now. I hope to delete the command line arguments in the future and solely rely on `.sourcekit-lsp` configuration files.
Environment variable will be migrated to `.sourcekit-lsp` in a follow-up commit.
Since the `Atomic*` types can not be marked as `Sendable` (because they aren’t C structs), we can change the variables to constants and can remove `nonisolated(unsafe)`.
We used C atomics but these were allocated as Swift variables. Even thought they were atomic, concurrent accesses to them could violate Swift’s exclusivity laws, raising thread sanitizer errors.
Allocate the C atomics using malloc to fix this problem.
rdar://129170128
This allows us to run `sourcekit-lsp index --project /path/to/project` to index a project. Intended to debugging purposes, eg.
- Profile the time it takes to index a project
- See if the project can be indexed successfully
- Look at signposts generated during indexing in Instruments to see whether indexing or preparation is the bottleneck and how well we can parallelize tasks.
