These two tests are exposing a use-after-free in the dependency scanner.
Disabling them for now so that I can fix the ASAN bots.
Disabled tests:
- ScanDependencies/error_path.swift
- ScanDependencies/error_source_locations.swift
This change modifies the dependency scanner to keep track of source locations of each encountered 'import' statement, in order to be able to emit diagnostics with source locations if an import failed to resolve.
- Keep track of each 'import' statement's source buffer, line number, and column number when adding it. The dependency scanner utilizes separate compilation instances, and therefore separate Source Managers for scanning `import` statements of user sources and textual interfaces of Swift dependencies. Since import resolution may happen in the main scanner compilation instance while the `import` itself was found by an interface-scanning sub-instance, we cannot simply hold on to the import's `SourceLoc`.
- Add libSwiftScan API for diagnostics to carry above source locations to clients.
