Overhaul the logic and method names involved in enabling and disabling
reference caching in `TupleTree<T>`. `TupleTreeReference<T, U>` now
lazily caches the target and will traverse the path only when needed.
Also expose and use these functions in the new pipeline, which should
provide some speedup when executing a `Schedule`.
Not every case can benefit from extra liniency, so they were manually
reviewed on a case by case basis.
Additionally, this drops a couple of "this should be a non-strict
specialization" commits, because of a bug with clang
(see the GenericGraph concepts rework commit for more details) as
to avoid confusion (we wouldn't want anyone trying to solve these
"todo"s) until the clang struct type deduction is fixed. Especially
considering that there are currently no cases where these softer
versions would be beneficial (we never inherit from templates in
question).
`DocumentError`s are the inteded way of propagating errors from the
pipeline to the frontend when a location is required to inform the user
of the error whereabouts.
We used to assign an uninitialized field to `false`. However, what we
really wanted to is to construct the optional by invoking the default
constructor of the `value_type` of the optional.
Model classes are now described by a YAML document, which is used to
generate C++ headers containing classes and all the boilerplate
required for YAML serialization/deserialization, usage in
SortedVectors, etc. See the README in include/revng/Model for more
info.
Alessandro Di Federico