Language server first pass

[micahscopes]

This is an initial implementation of the Fe language server. See the readme for further details.

Progress

May 2023

• Orientation, research and study of rust-analyzer, Fe compiler
• LSP server crate scaffolding
• LSP-based VSCode extension
• Hover prototype
  • printing debug information
• Basic development setup and documentation

June 2023

• Diagnostics publishing prototype
  • using current deprecated diagnostics functionality

July 2023

• Syntax highlighting in the VSCode extension via Textmate grammar file
• Initial work on transitioning to the new compiler architecture
  • Salsa2022 database setup for language server
  • Overhaul diagnostics types to support types in new compiler crates
  • Working prototype of new diagnostics functionality based on @Y-Nak's name-resolution branch

August 2023

• Improvements to LSP server + VSCode extension development setup
• Improved document/didChange handling
• Flexible LSP server global logging support using the log crate
• Further work on transitioning to the new compiler overhaul
  • Go-to definition prototype working for standalone .fe files; based on @Y-Nak's compiler rewrite
    • Name resolution from cursor position
    • Snap tests and unit tests for go-to definition functionality
  • Error handling improvements
    • At the time, the rewritten name resolution only supported type resolution in the early resolution stage, but the data types and LSP server implementation should seamlessly support progress on the new compiler's name resolution functionality without many changes

September 2023

• Go-to definition cleanup
• Initial "workspace" functionality
  • a data structure and API for generating, caching and synchronizing necessary salsa inputs to support language server functionality
  • should support file synchronization via filesystem watching and LSP file change events alike
  • Sketch of initial workspace cache data structures
    • Featuring a prefix tree based lookup for salsa inputs representing files, ingots and top-modules
    • Supporting local, external and standalone ingot caches.
  • Upgraded go-to definition functionality to work with "local" ingots containing multiple modules
  • Integration of workspace data structures with existing language server data structures; slight refactor of existing architecture
  • Initial workspace sync prototype and tests
• Initial support for subdiagnostics
• Research and study of rust-analyzer's file synchronization functionality
• Workspace sync API brainstorming and design

November/December 2023

• Improve the internal synchronization API for the "workspace" data structure to support an explicit update step
• Integrate the "workspace" data structure with LSP events and a rudimentary filesystem watcher

[sbillig]

🎉