`getLocation()` will now exists for all entities. When there is no
valid location, the location will still not be emitted in the DB, but
on the QL side we will then assign a special `UnknownLocation` with
empty filename and 0 for line/column start/end.
This unknown location is currently emitted (with a unique `@` key) at
the start of every extraction, but we can move it elsewhere (and
possibly in a unique global trap file) at a later stage, possibly after
or when we rework the trap file strategy.
This should solve flakiness that was observed on the control flow tests,
which is probably caused by the `nodes` predicate in the `TestOutput`
class in `ControlFlowGraphImplShared.qll` not able to assign a proper
rank when the node does not have a location.
By explicitly marking children in the `schema.yml` file, an internal
`getAChild` predicate is implemented, that is in turn used in `AstNode`
to implement `getParent`.
This is yet to be used in the control flow library to replace the
hand-rolled implementation.
A further, more complex step is to use the same information to fully
generate the core implementation of `PrintAst` (including the
accessor string). This will be done later.
The `parent` tests use the same swift code as the extractor tests, and
this is currently enforced by `sync-files.py`. Notice that `qltest.sh`
had to be modified to deal with multiple files, which was not working
yet.
This transfers the current state of `StmtVisitor` in the PoC, plus some
changes required for the update to swift 5.6.
Also `getLabel` in `SwiftDispatcher` got renamed to `createLabel`, and
is now correctly outputting the label assignment to the trap file.
This transfers the current state of `DeclVisitor` from the
proof-of-concept.
TODO: make the `declarations` tests in `extractor-tests` more
comprehensive.
This allows to avoid bypassing label type correcness in the extractor,
and allows to independently resolve TBD extractions, as with this
approach TBD nodes do have the correctly typed trap label. The TBD
status is now a predicate on the QL side.
This requires:
* a default visit using the correct type, which is achieved via macro
metaprogramming in `VisitorBase.h`, following the way
`swift::ASTVisitor` is programmed
* a mapping from labels to corresponding binding trap entries. The
functor is defined in `TrapTagTraits.h` and instantiated in generated
`TrapEntries.h`
* Binding trap entries for TBD unknown entities must not have any other
field than the `id` (after all, we are supposed to not extract them
yet). This is why all unextracted fields in `schema.yml` have been
commented out, and will be uncommentend when visitors are added
