- **Explanation**: Makes SymbolGraphGen use fully-qualified module names
when comparing modules for determining symbol sources.
- **Scope**: Fixes an uncommon bug when extending an Objective-C type
using a header with the same name as the source module's header.
- **Issues**: rdar://152676102
- **Original PRs**: #82112
- **Risk**: Low. The change does not affect normal compilation, and the
change will only affect which symbol graph a symbol is sorted into, and
shouldn't introduce any crashes.
- **Testing**: Automated tests verify the change.
- **Reviewers**: @franklinsch
