Co-authored-by: Dustin S. <dstackmasta27@gmail.com>
Co-authored-by: Ferenc Fejes <fejes@inf.elte.hu>
Co-authored-by: Maria José Solano <majosolano99@gmail.com>
Co-authored-by: Yochem van Rosmalen <git@yochem.nl>
Co-authored-by: brianhuster <phambinhanctb2004@gmail.com>
Co-authored-by: zeertzjq <zeertzjq@outlook.com>

Problem:
Per the documentation, passing `false` as the `enable` parameter of
`vim.lsp.enable()` should disable the given LSP(s), but it does not work
due to a logic error.

Specifically, `enable == false and nil or {}` will always evaluate to
`{}` because `nil` is falsy.

Solution:
Correct the conditional statement.

When `root_dir` is a function it can (and often will) call the provided
callback function in a fast API context (e.g. in the `on_exit` handler
of `vim.system`). When the callback function is executed we should
ensure that it runs vim.lsp.start on the main event loop.

Co-authored-by: Axel <axelhjq@gmail.com>
Co-authored-by: Colin Kennedy <colinvfx@gmail.com>
Co-authored-by: Daiki Noda <sys9kdr@users.noreply.github.com>
Co-authored-by: Evgeni Chasnovski <evgeni.chasnovski@gmail.com>
Co-authored-by: Jean-Jacq du Plessis <1030058+jj-du-plessis@users.noreply.github.com>
Co-authored-by: Juan Giordana <juangiordana@gmail.com>
Co-authored-by: Lincoln Wallace <locnnil0@gmail.com>
Co-authored-by: Matti Hellström <hellstrom@scm.com>
Co-authored-by: Steven Locorotondo <steven.locorotondo@justeattakeaway.com>
Co-authored-by: Yochem van Rosmalen <git@yochem.nl>
Co-authored-by: glepnir <glephunter@gmail.com>
Co-authored-by: ifish <fishioon@live.com>

Allows to retrieve the configuration as it will be used by `lsp.enable`
- including the parts merged from `*` and rtp.

This is useful for explicit startup control
(`vim.lsp.start(vim.lsp.config[name])`)

Closes https://github.com/neovim/neovim/issues/31640

If root_dir is a function it is evaluated when the client is created to
determine the root directory.

This enables dynamically determining the root directory based on e.g.
project or directory structure (example: finding a parent Cargo.toml
file that contains "[workspace]" in a Rust project).

Problem: LSP configs on the runtimepath must have the same name as the
LSP server and must also explicitly set the name in vim.lsp.config. This
is redundant and creates a footgun where a user may accidentally use the
wrong name when assigning to the vim.lsp.config table.

Solution: Return a table from lsp/ runtimepath files instead

Problem:
regression since https://github.com/neovim/neovim/pull/31340

`nvim -l repro.lua`:
```lua
vim.lsp.start { cmd = { 'lua-language-server' }, name = 'lua_ls' }
vim.lsp.start { cmd = { 'lua-language-server' }, name = 'lua_ls', root_dir = 'foo' }

-- swapped case will be ok:
-- vim.lsp.start { cmd = { 'lua-language-server' }, name = 'lua_ls', root_dir = 'foo' }
-- vim.lsp.start { cmd = { 'lua-language-server' }, name = 'lua_ls' }
```

Failure:
```
E5113: Error while calling lua chunk: /…/lua/vim/lsp.lua:214: bad argument #1 to
'ipairs' (table expected, got nil)
stack traceback:
        [C]: in function 'ipairs'
        /…/lua/vim/lsp.lua:214: in function 'reuse_client'
        /…/lua/vim/lsp.lua:629: in function 'start'
        repro.lua:34: in main chunk
```