Our mangler is split in two version:
* `SwiftTrapMangler`, with the same behaviour as the previous
`SwiftMangler`, constructing mangled names with trap label references
* `SwiftRecursiveMangler` that replaces trap label references with
recursive calls to its own `mangle` functions, effectively rolling out
the entire chain of references
The latter is used to create lazy trap file names. Hashing is used to
avoid excessively long filenames.
* visiting now happens in a later stage than fetching labels. While
fetching a list of entities to be visited is created, and then acted
upon in actual extraction. This partially flattens the recursive
nature of `fetchLabel` into a loop inside `SwiftVisitor::extract`.
Recursion in `fetchLabel` will only happen on labels fetched while
naming an entity (calling into `SwiftMangler`).
* The choice whether to name a declaration or type has been moved from
the translators to `SwiftMangler`. Acting on this choice is contained
in `SwiftDispatcher::createLabel`.
* The choice whether to emit a body of a declaration has been moved from
`DeclTranslator` to the dispatcher. This choice is also contained in
`SwiftDispatcher::createLabel`.
* The simple functionality of the `LabelStore` has been moved to the
`SwiftDispatcher` as well.
In case the extractor is run in isolation for debugging/testing, this
will avoid littering the current working directory with artifacts, and
instead having a single `extractor-out` directory to inspect or clean
up.
Also extractor logs have been nested into a `swift` directory, as the
log directory provided by the `codeql` cli is actually shared between
languages.
This is done by adding a `isSuccessfullyExtracted` predicate that is
filled for primary files at the very end of the extractor invocation if
the frontend was performed successfully. If for example the extractor
crashes this will therefore not be filled.
The upgrade script is written so that `SuccessfullyExtractedFiles.ql`
on an upgraded script will give exactly the same results as before it.
`weakly_canonical` will resolve as much as possible in the path, and not
return an error if it can't resolve everything (for example due to a
non existant file). In any case in case of problems with the file we
will see an error when actually using the resolved path.
This tunes down some unhelpful log messages.
