Problem: LuaLS struggles with the generics used in Nvim's runtime,
requiring broad diagnostic suppressions. Indexing is also slow.
Solution: Use EmmyLua for type checks in the build and CI. It offers
more sophisticated type checking, substantially better support for
generics, and much better flow analysis.
Correct the affected annotations. Use `@internal`, supported directly by
EmmyLua, instead of `@nodoc` for shared internal declarations, and
support it in the help parser.
AI-assisted
Problem:
- Choosing a new EXX error code is tedious.
- It's possible to accidentally use an EXX error code for different
purposes.
Solution:
Add a lint check which requires EXX error codes to have a :help tag.
This also avoids duplicates because `make doc` does `:helptags ++t doc`
which fails if duplicates are found.
Problem:
We want to encourage implementing core features in Lua instead of C, but
it's clumsy because:
- Core Lua code (built into `nvim` so it is available even if VIMRUNTIME
is missing/invalid) requires manually updating CMakeLists.txt, or
stuffing it into `_editor.lua`.
- Core Lua modules are not organized similar to C modules, `_editor.lua`
is getting too big.
Solution:
- Introduce `_core/` where core Lua code can live. All Lua modules added
there will automatically be included as bytecode in the `nvim` binary.
- Move these core modules into `_core/*`:
```
_defaults.lua
_editor.lua
_options.lua
_system.lua
shared.lua
```
TODO:
- Move `_extui/ => _core/ui2/`
