Investigate using the new Kotlin analysis API

[fwcd]

Update (June 2022):

A prototype of a language server using the new analysis APIs can be found in the kotlin-analysis-server repo. Note that this is not production ready and mostly intended as a playground for experimentation currently.

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The Kotlin frontend is currently undergoing large architectural changes with the migration to FIR and will provide some new APIs for IDE-related usage that we could hook into, once ready.

The interesting modules seem to be mostly located in analysis (in the Kotlin repo). Useful resources:

• Official Kotlin repo:
  • The docs for the analysis API
    • ...including this overview of the API (explicitly mentions LSP as a use case)
    • ...and this usage doc
  • KtAnalysisSession from analysis
  • The analysis-api-standalone project
• IntelliJ IDEA repo:
  • The new Kotlin plugin, along with its implementation of completions
• Kotlin Symbol Processor (KSP):
  • An example project using the standalone analysis API
  • See this build.gradle.kts for an example of the Maven repos and dependencies needed for the analysis API
  • See this main method for an example how to bootstrap the compiler/analysis APIs
• Kotlin Website:
  • This roadmap
• YouTrack:
  • This issue tracking standalone mode for the analysis API (explicitly mentions LSP as a use case)
  • This issue regarding prototyping of an IDE plugin
  • This issue regarding use of Analysis API with Frontend 1.0
• Kotlin Blog:
  • This blog post: The road to the K2 compiler
    • The linked YouTube video, which includes an overview over the new compiler architecture
• Kotlin Slack (requires invitation, see here):
  • Discussion of some FIR internals
  • This diagram of the Kotlin compiler architecture

[lppedd]

Might be useful! https://kotlin.github.io/analysis-api/index_md.html

[amgdev9]

Hi! Got the analysis api working with the features needed to develop an lsp server, PoC here: https://github.com/amgdev9/kotlin-lsp, this api helps with having diagnostics and incremental updates, but integration with build systems and an indexing solution is not part of the api and must be developed separately

[lppedd]

Hey, that's cool!

I also want to mention (if you didn't know already) that an LSP is part of GSoC 2025. So whoever is working on it might be able to get good help.

[lppedd]

BTW @amgdev9, did the answer provided in KT-74247 help in any way? I was curious about the custom "analysis API platform".

[amgdev9]

BTW @amgdev9, did the answer provided in KT-74247 help in any way? I was curious about the custom "analysis API platform".

That response helped me so much, the poc is a custom platform implementation, doing it this way there is no limitation with file mutation as opposed to using the standalone platform. It was tough to implement nonetheless as the docs are so little and I had to dig deep in the kotlin codebase to understand all the moving pieces

Hey, that's cool!

I also want to mention (if you didn't know already) that an LSP is part of GSoC 2025. So whoever is working on it might be able to get good help.

OMG I cant believe the lsp is finally in their roadmap 😂, seriously you have made my day. Anyway if this poc becomes useless as we will now have official support at least I learned a ton about compilers, analysis and stuff, so well I dont regret it in the end

[lppedd]

Anyway if this poc becomes useless

I think it's the contrary. GSoC is a community effort, so while it appears they finally caved and decided to give the LSP some level of priority, the owner of the effort is still the community, in this specific case you and all the people trying to understand how to do it.

This is a good opportunity to have a bigger "team" working on it. I would give it a shot and maybe ask someone from JetBrains how to approach it as part of GSoC. Or at least let them know there is a starting point.

[amgdev9]

Anyway if this poc becomes useless

I think it's the contrary. GSoC is a community effort, so while it appears they finally caved and decided to give the LSP some level of priority, the owner of the effort is still the community, in this specific case you and all the people trying to understand how to do it.

This is a good opportunity to have a bigger "team" working on it. I would give it a shot and maybe ask someone from JetBrains how to approach it as part of GSoC. Or at least let them know there is a starting point.

Oh, I see! Definitely I will contact JB in case I can help and provide all my research as a starting point