lsp: vim.lsp.diagnostic (#12655)

Breaking Changes:
- Deprecated all `vim.lsp.util.{*diagnostics*}()` functions.
    - Instead, all functions must be found in vim.lsp.diagnostic
    - For now, they issue a warning ONCE per neovim session. In a
      "little while" we will remove them completely.
- `vim.lsp.callbacks` has moved to `vim.lsp.handlers`.
    - For a "little while" we will just redirect `vim.lsp.callbacks` to
      `vim.lsp.handlers`. However, we will remove this at some point, so
      it is recommended that you change all of your references to
      `callbacks` into `handlers`.
    - This also means that for functions like |vim.lsp.start_client()|
      and similar, keyword style arguments have moved from "callbacks"
      to "handlers". Once again, these are currently being forward, but
      will cease to be forwarded in a "little while".
- Changed the highlight groups for LspDiagnostic highlight as they were
  inconsistently named.
    - For more information, see |lsp-highlight-diagnostics|
- Changed the sign group names as well, to be consistent with
  |lsp-highlight-diagnostics|

General Enhancements:
- Rewrote much of the getting started help document for lsp. It also
  provides a much nicer configuration strategy, so as to not recommend
  globally overwriting builtin neovim mappings.

LSP Enhancements:
- Introduced the concept of |lsp-handlers| which will allow much better
  customization for users without having to copy & paste entire files /
  functions / etc.

Diagnostic Enhancements:
- "goto next diagnostic" |vim.lsp.diagnostic.goto_next()|
- "goto prev diagnostic" |vim.lsp.diagnostic.goto_prev()|
    - For each of the gotos, auto open diagnostics is available as a
      configuration option
- Configurable diagnostic handling:
    - See |vim.lsp.diagnostic.on_publish_diagnostics()|
    - Delay display until after insert mode
    - Configure signs
    - Configure virtual text
    - Configure underline
- Set the location list with the buffers diagnostics.
    - See |vim.lsp.diagnostic.set_loclist()|
- Better performance for getting counts and line diagnostics
    - They are now cached on save, to enhance lookups.
    - Particularly useful for checking in statusline, etc.
- Actual testing :)
    - See ./test/functional/plugin/lsp/diagnostic_spec.lua
- Added `guisp` for underline highlighting

NOTE: "a little while" means enough time to feel like most plugins and
plugin authors have had a chance to refactor their code to use the
updated calls. Then we will remove them completely. There is no need to
keep them, because we don't have any released version of neovim that
exposes these APIs. I'm trying to be nice to people following HEAD :)

Co-authored: [Twitch Chat 2020](https://twitch.tv/teej_dv)

1 files changed, 16 insertions, 0 deletions

diff --git a/runtime/lua/vim/highlight.lua b/runtime/lua/vim/highlight.lua
index 705b34dc99..0012dce081 100644
--- a/runtime/lua/vim/highlight.lua
+++ b/runtime/lua/vim/highlight.lua
@@ -2,6 +2,22 @@ local api = vim.api
 
 local highlight = {}
 
+--@private
+function highlight.create(higroup, hi_info, default)
+  local options = {}
+  -- TODO: Add validation
+  for k, v in pairs(hi_info) do
+    table.insert(options, string.format("%s=%s", k, v))
+  end
+  vim.cmd(string.format([[highlight %s %s %s]], default and "default" or "", higroup, table.concat(options, " ")))
+end
+
+--@private
+function highlight.link(higroup, link_to, force)
+  vim.cmd(string.format([[highlight%s link %s %s]], force and "!" or " default", higroup, link_to))
+end
+
+
 --- Highlight range between two positions
 ---
 --@param bufnr number of buffer to apply highlighting to