adds gopls config

modules/nvim/config/lsp/gopls.lua

@@ -0,0 +1,99 @@
+---@brief
+---
+--- https://github.com/golang/tools/tree/master/gopls
+---
+--- Google's lsp server for golang.
+
+--- @class go_dir_custom_args
+---
+--- @field envvar_id string
+---
+--- @field custom_subdir string?
+
+local mod_cache = nil
+local std_lib = nil
+
+---@param custom_args go_dir_custom_args
+---@param on_complete fun(dir: string | nil)
+local function identify_go_dir(custom_args, on_complete)
+  local cmd = { "go", "env", custom_args.envvar_id }
+  vim.system(cmd, { text = true }, function(output)
+    local res = vim.trim(output.stdout or "")
+    if output.code == 0 and res ~= "" then
+      if custom_args.custom_subdir and custom_args.custom_subdir ~= "" then
+        res = res .. custom_args.custom_subdir
+      end
+      on_complete(res)
+    else
+      vim.schedule(function()
+        vim.notify(
+          ("[gopls] identify " .. custom_args.envvar_id .. " dir cmd failed with code %d: %s\n%s"):format(
+            output.code,
+            vim.inspect(cmd),
+            output.stderr
+          )
+        )
+      end)
+      on_complete(nil)
+    end
+  end)
+end
+
+---@return string?
+local function get_std_lib_dir()
+  if std_lib and std_lib ~= "" then
+    return std_lib
+  end
+
+  identify_go_dir({ envvar_id = "GOROOT", custom_subdir = "/src" }, function(dir)
+    if dir then
+      std_lib = dir
+    end
+  end)
+  return std_lib
+end
+
+---@return string?
+local function get_mod_cache_dir()
+  if mod_cache and mod_cache ~= "" then
+    return mod_cache
+  end
+
+  identify_go_dir({ envvar_id = "GOMODCACHE" }, function(dir)
+    if dir then
+      mod_cache = dir
+    end
+  end)
+  return mod_cache
+end
+
+---@param fname string
+---@return string?
+local function get_root_dir(fname)
+  if mod_cache and fname:sub(1, #mod_cache) == mod_cache then
+    local clients = vim.lsp.get_clients({ name = "gopls" })
+    if #clients > 0 then
+      return clients[#clients].config.root_dir
+    end
+  end
+  if std_lib and fname:sub(1, #std_lib) == std_lib then
+    local clients = vim.lsp.get_clients({ name = "gopls" })
+    if #clients > 0 then
+      return clients[#clients].config.root_dir
+    end
+  end
+  return vim.fs.root(fname, "go.work") or vim.fs.root(fname, "go.mod") or vim.fs.root(fname, ".git")
+end
+
+---@type vim.lsp.Config
+return {
+  cmd = { "gopls" },
+  filetypes = { "go", "gomod", "gowork", "gotmpl" },
+  root_dir = function(bufnr, on_dir)
+    local fname = vim.api.nvim_buf_get_name(bufnr)
+    get_mod_cache_dir()
+    get_std_lib_dir()
+    -- see: https://github.com/neovim/nvim-lspconfig/issues/804
+    on_dir(get_root_dir(fname))
+  end,
+}