Previously we had some heuristics in the backends trying to achieve this with a
lot of holes ; this should be much more solid, relying on `Bindlib` to do the
correct renamings.
**Note1**: it's not plugged into the backends other than OCaml at the moment.
**Note2**: the related, obsolete heuristics haven't been cleaned out yet
**Note3**: we conservatively suppose a single namespace at the moment. This is
required for e.g. Python, but it forces vars named like struct fields to be
renamed, which is more verbose in e.g. OCaml. The renaming engine could be
improved to support different namespaces, with a way to select how to route the
different kinds of identifiers into them.
Similarly, customisation for what needs to be uppercase or lowercase is not
available yet.
**Note4**: besides excluding keywords, we should also be careful to exclude (or
namespace):
- the idents used in the runtime (e.g. `o_add_int_int`)
- the dynamically generated idents (e.g. `embed_*`)
**Note5**: module names themselves aren't handled yet. The reason is that they
must be discoverable by the user, and even need to match the filenames, etc. In
other words, imagine that `Mod` is a keyword in the target language. You can't
rename a module called `Mod` to `Mod1` without knowing the whole module context,
because that would destroy the mapping for a module already called `Mod1`.
A reliable solution would be to translate all module names to e.g.
`CatalaModule_*`, which we can assume will never conflict with any built-in, and
forbid idents starting with that prefix. We may also want to restrict their
names to ASCII ? Currently we use a projection, but what if I have two modules
called `Là` and `La` ?
This includes a few separate changes:
- pass visibility information of declarations (depending on wether the
declaration was in a ```catala-metadata block or not)
- add reasonable hash computation functions to discriminate the interfaces. In
particular:
* Uids have a `hash` function that depends on their string, but not on their
actual uid (which is not stable between runs of the compiler) ; the existing
`hash` function and its uses have been renamed to `id`.
* The `Hash` module provides the tools to properly combine hashes, etc. While
we rely on `Hashtbl.hash` for the atoms, we take care not to use it on any
recursive structure (it relies on a bounded traversal).
- insert the hashes in the artefacts, and properly check and report those (for
OCaml)
**Remains to do**:
- Record and check the hashes in the other backends
- Provide a way to get stable inline-test outputs in the presence of module
hashes
- Provide a way to write external modules that don't break at every Catala
update.
This changes the `decl_ctx` to be toplevel only, with flattened references to
uids for most elements. The module hierarchy, which is still useful in a few
places, is kept separately.
Module names are also changed to UIDs early on, and support for module aliases
has been added (needs testing).
This resolves some issues with lookup, and should be much more robust, as well
as more convenient for most lookups.
The `decl_ctx` was also extended for string ident lookups, which avoids having
to keep the desugared resolution structure available throughout the compilation
chain.
rather than scattered in structures
The context is still hierarchical for defs though, so one needs to retrieve the
path to lookup in the correct context for info. Exceptions are enums and struct
defs, which are re-exposed at toplevel.
The module is renamed to `Mark`, and functions renamed to avoid redundancy:
`Marked.mark` is now `Mark.add`
`Marked.unmark` is now `Mark.remove`
`Marked.map_under_mark` is now simply `Mark.map`
etc.
`Marked.same_mark_as` is replaced by `Mark.copy`, but with the arguments
swapped (which seemed more convenient throughout)
Since a type `Mark.t` would indicate a mark, and to avoid confusion, the type
`Marked.t` is renamed to `Mark.ed` as a shorthand for `Mark.marked` ; this part
can easily be removed if that's too much quirkiness.
