We currently allow sending requests to the BSP server before `build/initialize` returns. This is not valid in general and we should wait for the initialize result before sending any other messages.
rdar://136111469
When you had a package at `/pkg_real` and a symlink `/pkg` pointing to `/pkg_real`, then opened a workspace at `/pkg`, we wouldn’t get any build settings for any of the files. This was masked in tests because they still called `SwiftPMBuildSystem.targets(for:)`, which handled symlink resolution but wasn’t called in production.
Handle symlink resolution `BuildSystemManager`, remove `SwiftPMBuildSystem.targets(for:)` and its related members/methods, and migrate the tests to go through `BuildSystemManager`, which is what production code does. A nice side effect of this is that the tests will log the requests sent to the build system.
We had a retain cycle from `BuildSystemManager` to `LocalConnection`. Fix it by making `LocalConnection` have a weak reference to `BuildSystemManager`.
`buildTarget/inverseSources` is not required to be implemented by BSP servers and we have almost all information needed for it in `BuildSystemManager`.
This also makes sure that `buildTarget/sources` and `buildTarget/inverseSources` actually match each other. Before this change, we had source files like `Package.swift` for which we returned a target from `buildTarget/inverseSources` but that weren’t part of that target’s sources retrieved using `buildTarget/sources`.
The implementation of which file’s dependencies have been updated is common across all build systems and thus build systems shouldn’t need to implement this logic. This also allows us to remove `BuildSystemDelegate`.
`Workspace` is responsible for creating the `BuildSystemManager` and responds to most of the delegate calls. It should thus also be the delegate of `BuildSystemManager`.
This finalizes the move of `BuiltInBuildSystem` creation into `BuiltInBuildSystemAdapter` and means that we can set the message handler of the `BuiltInBuildSystem` during initialization instead of using a setter method.
This way we create the `BuiltInBuildSystem` at the same time that we create the `BuildSystemManager`, which gets us one step closer to creating the `BuiltInBuildSystem` from the `BuiltInBuildSystemAdapter`.
