refactor: create function for deferred loading

The benefit of this is that users only pay for what they use. If e.g.
only `vim.lsp.buf_get_clients()` is called then they don't need to load
all modules under `vim.lsp` which could lead to significant startuptime
saving.

Also `vim.lsp.module` is a bit nicer to user compared to
`require("vim.lsp.module")`.

This isn't used for some nested modules such as `filetype` as it breaks
tests with error messages such as "attempt to index field 'detect'".
It's not entirely certain the reason for this, but it is likely it is
due to filetype being precompiled which would imply deferred loading
isn't needed for performance reasons.

7 files changed, 17 insertions, 19 deletions

diff --git a/runtime/lua/vim/lsp/_completion.lua b/runtime/lua/vim/lsp/_completion.lua
index 7a607d6c13..84dbf9083e 100644
--- a/runtime/lua/vim/lsp/_completion.lua
+++ b/runtime/lua/vim/lsp/_completion.lua
@@ -8,7 +8,7 @@ local ms = protocol.Methods
 ---@return string parsed snippet
 local function parse_snippet(input)
   local ok, parsed = pcall(function()
-    return require('vim.lsp._snippet_grammar').parse(input)
+    return vim.lsp._snippet_grammar.parse(input)
   end)
   return ok and tostring(parsed) or input
 end
@@ -206,7 +206,7 @@ function M.omnifunc(findstart, base)
     local params = util.make_position_params(win, client.offset_encoding)
     client.request(ms.textDocument_completion, params, function(err, result)
       if err then
-        require('vim.lsp.log').warn(err.message)
+        vim.lsp.log.warn(err.message)
       end
       if result and vim.fn.mode() == 'i' then
         local matches
diff --git a/runtime/lua/vim/lsp/_dynamic.lua b/runtime/lua/vim/lsp/_dynamic.lua
index 5edb27b498..3c9dee2c69 100644
--- a/runtime/lua/vim/lsp/_dynamic.lua
+++ b/runtime/lua/vim/lsp/_dynamic.lua
@@ -1,4 +1,4 @@
-local glob = require('vim.glob')
+local glob = vim.glob
 
 --- @class lsp.DynamicCapabilities
 --- @field capabilities table<string, lsp.Registration[]>
diff --git a/runtime/lua/vim/lsp/_watchfiles.lua b/runtime/lua/vim/lsp/_watchfiles.lua
index af4cc65f71..59b8c38166 100644
--- a/runtime/lua/vim/lsp/_watchfiles.lua
+++ b/runtime/lua/vim/lsp/_watchfiles.lua
@@ -1,6 +1,6 @@
 local bit = require('bit')
-local glob = require('vim.glob')
-local watch = require('vim._watch')
+local glob = vim.glob
+local watch = vim._watch
 local protocol = require('vim.lsp.protocol')
 local ms = protocol.Methods
 local lpeg = vim.lpeg
diff --git a/runtime/lua/vim/lsp/diagnostic.lua b/runtime/lua/vim/lsp/diagnostic.lua
index cba5b66672..46dda01e3f 100644
--- a/runtime/lua/vim/lsp/diagnostic.lua
+++ b/runtime/lua/vim/lsp/diagnostic.lua
@@ -1,8 +1,6 @@
 ---@brief lsp-diagnostic
 
-local util = require('vim.lsp.util')
 local protocol = require('vim.lsp.protocol')
-local log = require('vim.lsp.log')
 local ms = protocol.Methods
 
 local api = vim.api
@@ -95,7 +93,7 @@ local function tags_lsp_to_vim(diagnostic, client_id)
       tags = tags or {}
       tags.deprecated = true
     else
-      log.info(string.format('Unknown DiagnosticTag %d from LSP client %d', tag, client_id))
+      vim.lsp.log.info(string.format('Unknown DiagnosticTag %d from LSP client %d', tag, client_id))
     end
   end
   return tags
@@ -425,7 +423,7 @@ end
 local function _refresh(bufnr, opts)
   opts = opts or {}
   opts['bufnr'] = bufnr
-  util._refresh(ms.textDocument_diagnostic, opts)
+  vim.lsp.util._refresh(ms.textDocument_diagnostic, opts)
 end
 
 --- Enable pull diagnostics for a buffer
diff --git a/runtime/lua/vim/lsp/handlers.lua b/runtime/lua/vim/lsp/handlers.lua
index 6ed8e1d40f..26a71487e2 100644
--- a/runtime/lua/vim/lsp/handlers.lua
+++ b/runtime/lua/vim/lsp/handlers.lua
@@ -120,7 +120,7 @@ M[ms.client_registerCapability] = function(_, result, ctx)
   local unsupported = {}
   for _, reg in ipairs(result.registrations) do
     if reg.method == ms.workspace_didChangeWatchedFiles then
-      require('vim.lsp._watchfiles').register(reg, ctx)
+      vim.lsp._watchfiles.register(reg, ctx)
     elseif not client.dynamic_capabilities:supports_registration(reg.method) then
       unsupported[#unsupported + 1] = reg.method
     end
@@ -144,7 +144,7 @@ M[ms.client_unregisterCapability] = function(_, result, ctx)
 
   for _, unreg in ipairs(result.unregisterations) do
     if unreg.method == ms.workspace_didChangeWatchedFiles then
-      require('vim.lsp._watchfiles').unregister(unreg, ctx)
+      vim.lsp._watchfiles.unregister(unreg, ctx)
     end
   end
   return vim.NIL
@@ -223,19 +223,19 @@ M[ms.workspace_workspaceFolders] = function(_, _, ctx)
 end
 
 M[ms.textDocument_publishDiagnostics] = function(...)
-  return require('vim.lsp.diagnostic').on_publish_diagnostics(...)
+  return vim.lsp.diagnostic.on_publish_diagnostics(...)
 end
 
 M[ms.textDocument_diagnostic] = function(...)
-  return require('vim.lsp.diagnostic').on_diagnostic(...)
+  return vim.lsp.diagnostic.on_diagnostic(...)
 end
 
 M[ms.textDocument_codeLens] = function(...)
-  return require('vim.lsp.codelens').on_codelens(...)
+  return vim.lsp.codelens.on_codelens(...)
 end
 
 M[ms.textDocument_inlayHint] = function(...)
-  return require('vim.lsp.inlay_hint').on_inlayhint(...)
+  return vim.lsp.inlay_hint.on_inlayhint(...)
 end
 
 --see: https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_references
@@ -643,7 +643,7 @@ end
 
 ---@see https://microsoft.github.io/language-server-protocol/specification/#workspace_inlayHint_refresh
 M[ms.workspace_inlayHint_refresh] = function(err, result, ctx, config)
-  return require('vim.lsp.inlay_hint').on_refresh(err, result, ctx, config)
+  return vim.lsp.inlay_hint.on_refresh(err, result, ctx, config)
 end
 
 -- Add boilerplate error validation and logging for all of these.
diff --git a/runtime/lua/vim/lsp/health.lua b/runtime/lua/vim/lsp/health.lua
index fe06006108..9c989e5246 100644
--- a/runtime/lua/vim/lsp/health.lua
+++ b/runtime/lua/vim/lsp/health.lua
@@ -5,7 +5,7 @@ function M.check()
   local report_info = vim.health.info
   local report_warn = vim.health.warn
 
-  local log = require('vim.lsp.log')
+  local log = vim.lsp.log
   local current_log_level = log.get_level()
   local log_level_string = log.levels[current_log_level]
   report_info(string.format('LSP log level : %s', log_level_string))
diff --git a/runtime/lua/vim/lsp/util.lua b/runtime/lua/vim/lsp/util.lua
index cee09d85e0..b5e15e135c 100644
--- a/runtime/lua/vim/lsp/util.lua
+++ b/runtime/lua/vim/lsp/util.lua
@@ -3,7 +3,7 @@ local snippet = require('vim.lsp._snippet_grammar')
 local validate = vim.validate
 local api = vim.api
 local list_extend = vim.list_extend
-local highlight = require('vim.highlight')
+local highlight = vim.highlight
 local uv = vim.uv
 
 local npcall = vim.F.npcall
@@ -636,7 +636,7 @@ end
 ---@see complete-items
 function M.text_document_completion_list_to_complete_items(result, prefix)
   vim.deprecate('vim.lsp.util.text_document_completion_list_to_complete_items()', nil, '0.11')
-  return require('vim.lsp._completion')._lsp_to_complete_items(result, prefix)
+  return vim.lsp._completion._lsp_to_complete_items(result, prefix)
 end
 
 --- Like vim.fn.bufwinid except it works across tabpages.