When querying a Swift module, the scanner now also keeps track of all discovered candidate binary modules which are not compatible with current compilation.
- If a Swift dependency is successfully resolved to a compatible binary module or a textual interface, a warning is emitted for every incompatible binary Swift module discovered along the way.
- If a Swift dependency is not resolved, but incompatible module candidates were found, an error is emitted - while it is likely that the scan would fail downstream, it is also possible that an underlying Clang module dependency (with the same name) is successfuly resolved and the Swift lookup failure is ignored, which is still going to lead to failures most of the time if the client code assumes the presence of the Swift overlay module in this scenario.
This change refactors common error reporting by the scanner into a 'ModuleDependencyIssueReporter' class, which also keeps track of all diagnosed failed lookups to avoid repeating diagnostics.
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.
