nvim: plugins: Drop nvim-lightbulb

Drop nvim-lightbulb and just add the needed functionality. This also
fixes a minor bug where the code action detection was incorrectly
being done under codeLensProvider instead of codeActionProvider.

nvim/.config/nvim/after/plugin/nvim-lightbulb.lua

@@ -1,23 +0,0 @@
-require'nvim-lightbulb'.update_lightbulb {
-  sign = {
-    enabled  = true,
-    priority = 10,
-  },
-  float = {
-    enabled  = false,
-    text     = "💡",
-    win_opts = {},
-  },
-  virtual_text = {
-    enabled = false,
-    text    = "💡",
-  },
-  status_text = {
-    enabled          = false,
-    text             = "💡",
-    text_unavailable = ""
-  },
-  autocmd = {
-    enabled = false,
-  }
-}

nvim/.config/nvim/lua/lsp.lua

@@ -1,5 +1,5 @@
-local protocol   = require 'vim.lsp.protocol'
-local lightbulb  = require 'nvim-lightbulb'
+local protocol = require 'vim.lsp.protocol'
+local lsp_util = vim.lsp.util
 
 vim.lsp.set_log_level("off")
 
@@ -73,6 +73,32 @@ local lsp_key_mappings = {
   { "codeLensProvider", 'n', '<LocalLeader>L', '<cmd>lua vim.lsp.codelens.clear()<CR>' },
 }
 
+local CODE_ACTION_AVAILABLE = "CodeActionAvailable"
+local CODE_ACTION_GROUP     = "code-action-group"
+
+if vim.tbl_isempty(vim.fn.sign_getdefined(CODE_ACTION_AVAILABLE)) then
+  vim.fn.sign_define(CODE_ACTION_AVAILABLE, { text = "💡", texthl = "DiagnosticSignInfo" })
+end
+
+local code_action_update_sign = function(old_line, new_line, bufnr)
+  bufnr = bufnr or "%"
+
+  if old_line then
+    vim.fn.sign_unplace(
+      CODE_ACTION_GROUP, { id = old_line, buffer = bufnr }
+    )
+    vim.b.code_action_line = nil
+  end
+
+  if new_line and (vim.b.code_action_line ~= new_line) then
+    vim.fn.sign_place(
+      new_line, CODE_ACTION_GROUP, CODE_ACTION_AVAILABLE, bufnr,
+      { lnum = new_line, priority = 10 }
+    )
+    vim.b.code_action_line = new_line
+  end
+end
+
 local cargo_reload_workspace = function()
   vim.lsp.buf_request(0, 'rust-analyzer/reloadWorkspace', nil, function(err)
     if err then
@@ -168,17 +194,33 @@ local on_attach = function(client, bufnr)
     end
   end
 
+  if client.server_capabilities.codeActionProvider then
+    vim.api.nvim_create_autocmd({"CursorHold", "CursorHoldI"}, {
+      group    = lsp_augroup_id,
+      buffer   = bufnr,
+      callback = function()
+        -- Taken from https://github.com/neovim/nvim-lspconfig/wiki/Code-Actions
+        local context  = { diagnostics = vim.lsp.diagnostic.get_line_diagnostics() }
+        local params   = lsp_util.make_range_params()
+        params.context = context
+        vim.lsp.buf_request(0, 'textDocument/codeAction', params, function(err, result, ctx, config)
+          if result and not vim.tbl_isempty(result) then
+            local line = params.range.start.line
+            code_action_update_sign(vim.b.code_action_line, line + 1, bufnr)
+          else
+            code_action_update_sign(vim.b.code_action_line, nil, bufnr)
+          end
+        end)
+      end
+    })
+  end
+
   if client.server_capabilities.codeLensProvider then
     vim.api.nvim_create_autocmd({"CursorHold", "CursorHoldI", "InsertLeave"}, {
       group    = lsp_augroup_id,
       buffer   = bufnr,
       callback = vim.lsp.codelens.refresh,
     })
-    vim.api.nvim_create_autocmd({"CursorHold", "CursorHoldI"}, {
-      group    = lsp_augroup_id,
-      buffer   = bufnr,
-      callback = lightbulb.update_lightbulb,
-    })
   end
 
   if client.server_capabilities.documentHighlightProvider then

nvim/.config/nvim/lua/plugins.lua

@@ -17,7 +17,6 @@ require "paq" {
   'tpope/vim-dispatch'                ,
   'junegunn/vim-easy-align'           ,
   'nvim-lua/plenary.nvim'             ,
-  'kosayoda/nvim-lightbulb'           ,
   'mfussenegger/nvim-lint'            ,
   'nvim-treesitter/nvim-treesitter'   ,
   'mfussenegger/nvim-treehopper'      ,