Support for Rust

[Champii]

Hello !

I've started the work concerning the rust bindings of SourcetrailDB. It is a (very) early (and non yet working) version of those, made with rust-bindgen.

You can see the progress and contribute at https://github.com/Champii/SourcetrailDB/tree/master/resources_rust

The current approach is to use rust-bindgen directly on the generated static library, but that may be inefficient as rust-bindgen does not handle std types well (std::string for example). Their doc recommend to generate them all as opaque types, but then we lose the ability to use them.

One of the possible workaround is to create a C ABI to interface the C++ code with Rust, or to try the method used by the python bindings and wrap the most commonly used features in a lightweight and thus Rust-friendly C++ library.

I'll try them both and consider the one that fit the most.

Feel free to share your point of view on the matter, and/or throw some suggestions on the best way to handle that !

If I can be of any help, I'd be glad to :)

[astrolemonade]

How do you manage to represent lifetimes or variable shadowing in Sourcetrail?

[egraether]

@cata0309 We don't.

• Variables in global or class scope are stored as symboland must have a unique name. They show up in the graph.
• Variables in function scope are stored as local_symbol and must have a unique name as well, but that name is not displayed anywhere. So you can shadow a variable by supplying a different name, e.g. by adding the location of first declaration to it's name: var_a<5:2> and var_a<10:6>.

[astrolemonade]

In Rust lang you can do something like this

//Immutable by default
let x=16;
//But you can change its value and also its type with shadowing 
let x=vec![3.4,4.5];

How would you represent the variable x if it is in the same function? It can have the same name as in the example and still different meanings. There must be a way to distinguish the first declaration and the shadowing one. Is it possible to add some additional info to them like line position in a local_symbol in this case? I always asked myself how Sourcetrail would manage to deal with lifetimes and also with user created data types.

[egraether]

As mentioned, you can append info to the name of the local_symbol. It's up to the indexer author to decide whether these 2 variables are the same or not.

[jokeyrhyme]

Do you think it is possible to use the Rust language server for this work? That might make it possible to map all languages that have such a server (e.g. Go, TypeScript, etc) in a generic way into Sourcetrail

[yozlet]

@jokeyrhyme I was just wondering the same thing, because a well-implemented Language Server can handle most (maybe all?) of what Sourcetrail needs. I'll create a separate issue.

EDIT: Added as #20

[D1mon]

how is the project progressing? I've been waiting for a ~year. I really need rust language support. please do not abandon the project.

[astrolemonade]

@D1mon I am sorry to inform you but it looks like a dead end, things are moving slow.