chore: use client.request instead of buf_request (#1503)

* Use client.request directly instead of vim.lsp.buf_request to call methods
that are outside the official LSP specification, such as clangd's 
"textDocument/switchSourceHeader". 
* This avoids sending an inapplicable request to all servers, as we cannot
ahead of time validate the methods a given server supports.

3 files changed, 60 insertions, 38 deletions

diff --git a/lua/lspconfig/server_configurations/clangd.lua b/lua/lspconfig/server_configurations/clangd.lua
index 08cf307a..cda6ef43 100644
--- a/lua/lspconfig/server_configurations/clangd.lua
+++ b/lua/lspconfig/server_configurations/clangd.lua
@@ -3,22 +3,27 @@ local util = require 'lspconfig.util'
 -- https://clangd.llvm.org/extensions.html#switch-between-sourceheader
 local function switch_source_header(bufnr)
   bufnr = util.validate_bufnr(bufnr)
+  local clangd_client = util.get_active_client_by_name(bufnr, 'clangd')
   local params = { uri = vim.uri_from_bufnr(bufnr) }
-  vim.lsp.buf_request(
-    bufnr,
-    'textDocument/switchSourceHeader',
-    params,
-    util.compat_handler(function(err, result)
-      if err then
-        error(tostring(err))
-      end
-      if not result then
-        print 'Corresponding file cannot be determined'
-        return
-      end
-      vim.api.nvim_command('edit ' .. vim.uri_to_fname(result))
-    end)
-  )
+  if clangd_client then
+    clangd_client.request(
+      'textDocument/switchSourceHeader',
+      params,
+      util.compat_handler(function(err, result)
+        if err then
+          error(tostring(err))
+        end
+        if not result then
+          print 'Corresponding file cannot be determined'
+          return
+        end
+        vim.api.nvim_command('edit ' .. vim.uri_to_fname(result))
+      end),
+      bufnr
+    )
+  else
+    print 'method textDocument/switchSourceHeader is not supported by any servers active on the current buffer'
+  end
 end
 
 local root_pattern = util.root_pattern('compile_commands.json', 'compile_flags.txt', '.git')
diff --git a/lua/lspconfig/server_configurations/texlab.lua b/lua/lspconfig/server_configurations/texlab.lua
index 4bcb6c81..1e43976a 100644
--- a/lua/lspconfig/server_configurations/texlab.lua
+++ b/lua/lspconfig/server_configurations/texlab.lua
@@ -1,5 +1,4 @@
 local util = require 'lspconfig.util'
-local lsp = vim.lsp
 
 local texlab_build_status = vim.tbl_add_reverse_lookup {
   Success = 0,
@@ -17,39 +16,49 @@ local texlab_forward_status = vim.tbl_add_reverse_lookup {
 
 local function buf_build(bufnr)
   bufnr = util.validate_bufnr(bufnr)
+  local texlab_client = util.get_active_client_by_name(bufnr, 'texlab')
   local params = {
     textDocument = { uri = vim.uri_from_bufnr(bufnr) },
   }
-  lsp.buf_request(
-    bufnr,
-    'textDocument/build',
-    params,
-    util.compat_handler(function(err, result)
-      if err then
-        error(tostring(err))
-      end
-      print('Build ' .. texlab_build_status[result.status])
-    end)
-  )
+  if texlab_client then
+    texlab_client.request(
+      'textDocument/build',
+      params,
+      util.compat_handler(function(err, result)
+        if err then
+          error(tostring(err))
+        end
+        print('Build ' .. texlab_build_status[result.status])
+      end),
+      bufnr
+    )
+  else
+    print 'method textDocument/build is not supported by any servers active on the current buffer'
+  end
 end
 
 local function buf_search(bufnr)
   bufnr = util.validate_bufnr(bufnr)
+  local texlab_client = util.get_active_client_by_name(bufnr, 'texlab')
   local params = {
     textDocument = { uri = vim.uri_from_bufnr(bufnr) },
     position = { line = vim.fn.line '.' - 1, character = vim.fn.col '.' },
   }
-  lsp.buf_request(
-    bufnr,
-    'textDocument/forwardSearch',
-    params,
-    util.compat_handler(function(err, result)
-      if err then
-        error(tostring(err))
-      end
-      print('Search ' .. texlab_forward_status[result.status])
-    end)
-  )
+  if texlab_client then
+    texlab_client.request(
+      'textDocument/forwardSearch',
+      params,
+      util.compat_handler(function(err, result)
+        if err then
+          error(tostring(err))
+        end
+        print('Search ' .. texlab_forward_status[result.status])
+      end),
+      bufnr
+    )
+  else
+    print 'method textDocument/forwardSearch is not supported by any servers active on the current buffer'
+  end
 end
 
 -- bufnr isn't actually required here, but we need a valid buffer in order to
diff --git a/lua/lspconfig/util.lua b/lua/lspconfig/util.lua
index b6780aa9..c7f4eb53 100644
--- a/lua/lspconfig/util.lua
+++ b/lua/lspconfig/util.lua
@@ -414,4 +414,12 @@ function M.get_clients_from_cmd_args(arg)
   return vim.tbl_values(result)
 end
 
+function M.get_active_client_by_name(bufnr, servername)
+  for _, client in pairs(vim.lsp.buf_get_clients(bufnr)) do
+    if client.name == servername then
+      return client
+    end
+  end
+end
+
 return M