SCIP based Language Server & extension for VS Code

[guw]

Feature request description

I think it would be nice to have a VS Code extension and a Language Server based on SCIP, which provides typical IDE editing functions such as:

• Code completion
• Code/Source actions / Refactoring
• doc hovers
• Type search
• Code outline
• Code navigation
• Call Hierarchy
• Type Hierarchy
• Code lens (references/implementations)

Additional interesting functions (but which probably require language specific parsers/handlers)

• Code folding
• Code formatting (on-type/selection/file)
• Code snippets

Is your feature request related to a problem? If so, please describe.

In very large Java code bases it's easy to trigger scaling issues in any IDE. For example, when the Java classpath is significant size for IntelliJ and Eclipse to handle. There are thousands of components/modules/projects and seldomly everything needs to be setup fully within an IDE. However, all IDEs require a full classpath for most of the features to work correctly.

We recently invested into extending the VS Code Java language support to make it compatible with Bazel. It works ok but shows the scaling problems in large code bases.

https://github.com/salesforce/bazel-vscode-java/
https://github.com/salesforce/bazel-eclipse/

The idea of having a SCIP based LS in VS Code should solve the following problems:

• don't need full classpath setup
• reduce setup time (less initial indexing)
• discoverability (easier to find code that's not set up)

Ideally a SCIP based IDE integration would work with:

• indexes provided/hosted by a central SourceGraph installation (this needs details how to make that version safe)
• indexes available in Bazel remote cache (produced by some CI system)
• indexes built locally (eg., in a local feature branch)
• indexes built in memory based on modifications to source files not saved to disk yet

[guw]

@varungandhi-src Thanks for cross-linking the issue. Is there interest in collaborating on a LS extension? We are a SourceGraph customer and I am interested in chatting with you folks about it.

[mmanela]

Thanks for filing the issue. Building a SCIP based language server is a fascinating idea. While this is not an area we can actively invest in, we do have changes planned that may help with it. We are working on building stronger SCIP oriented apis that may help in building a language server. We are also happy to consult and answer questions if this is a project you want to move forward with.