I'm working on building an IDE, Handmade Hero-style [1]. Writing the code analysis part completely from scratch (parser, static analysis, building a database of the user's types), integrating with Neovim and gdb for seamless vi keybindings and debugging.

A related project is RemedyBG, which is a debugger trying to replace Visual Studio's debugger, and is also written without any third-party libraries: https://remedybg.itch.io/remedybg

[1] https://handmadehero.org/