Calling `setCurrentWorkingDirectory` on `getRealFileSystem` sets the
working directory for the process itself. This is unsafe for clients
such as SourceKit which can process multiple concurrent requests,
and may be used as an in-process library in e.g sourcekit-lsp. Switch
to `createPhysicalFileSystem` instead, where setting the working
directory is done locally on the FileSystem itself.
The diagnostic group documentation now point to the swift.org URL rather
than the toolchain path, so it no longer needs to be passed all the way
through sourcekitd.
Resolves rdar://151500502.
Although I don't plan to bring over new assertions wholesale
into the current qualification branch, it's entirely possible
that various minor changes in main will use the new assertions;
having this basic support in the release branch will simplify that.
(This is why I'm adding the includes as a separate pass from
rewriting the individual assertions)
It appears that a6ebd3083d changed the behavior of `-fno-modules-validate-system-headers` (aka. `DisableModulesValidateSystemDependencies`) in conjunction with `-fmodules-validate-once-per-build-session`: Before that change, `-fno-modules-validate-system-headers` needed to be passed for `-fmodules-validate-once-per-build-session` to have any effect (we were always validating system dependencies if `-fno-modules-validate-once-per-build-session` was not set). After the change, `-fno-modules-validate-once-per-build-session` causes system dependencies to never be validated, independent of the build session timestamp.
This change should have no effect on Xcode because it adds `-fmodules-validate-system-headers` to the compiler arguments for Swift files, which overrides `SearchPathOpts.DisableModulesValidateSystemDependencies = true;`
Driver uses its path to derive the plugin paths (i.e.
'lib/swift/host/plugins' et al.) Previously it was a constant string
'swiftc' that caused SourceKit failed to find dylib plugins in the
toolchain. Since 'SwiftLangSupport' knows the swift-frontend path,
use it, but replacing the filename with 'swiftc', to derive the plugin
paths.
rdar://107849796
