This gives the injected build system more flexibility by being able to respond to all BSP messages instead of only those methods defined in `BuiltInBuildSystem`.
I feel like the implementations are actually simpler if we split them. This will also allow us to add more advanced logic to the JSON compilation database build system in the future, such as inferring the toolchain from the compile command.
There were a few places that options only took place *after* determining
a build system, even though we have multiple that impact the search (eg.
`defaultBuildSystem` and `searchPaths`).
Additionally track project root and configuration paths separately, so
that when searching for implicit workspaces we can make sure to skip
creating duplicates.
This allows us to clean up the creation of `TestBuildSystem` a little bit because the tests can create `TestBuildSystem` instead of retrieving it from the `BuildSystemManager`.
rdar://142906050
We made quite a few fixes recently to make sure that path handling works correctly using `URL` on Windows. Use `URL` in most places to have a single type that represents file paths instead of sometimes using `AbsolutePath`.
While doing so, also remove usages of `TSCBasic.FileSystem` an `InMemoryFileSystem`. The pattern of using `InMemoryFileSystem` for tests was never consistently used and it was a little confusing that some types took a `FileSystem` parameter while other always assumed to work on the local file system.
`URL.path` returns forward slashes in the path on Windows (https://github.com/swiftlang/swift-foundation/issues/973) where we expect backslashes. Work around that by defining our own `filePath` property that is backed by `withUnsafeFileSystemRepresentation`, which produces backslashes.
rdar://137963660
The interaction to an out-of-process BSP server still went through the `BuildServerBuildSystem`, which doesn’t forward all messages to the build system and uses the old push-based model for build settings.
If we discover that the BSP server supports the new pull-based build settings model, we now forward all methods to it directly, without going through `BuiltInBuildSystemAdapter`, which has been renamed to `LegacyBuildServerBuildSystem`.
rdar://136106323
rdar://127606323
rdar://126493405
Fixes#1226Fixes#1173
