The 29th version of GNU Emacs is probably going to be released sometime this year (2023). This version introduces awesome new features such as:

• eglot, a Language Server Protocol client
• use-package for simplified package configuration
• treesit source code parsing with tree-sitter

These features makes it possible to have a complete development environment for Go with built-in GNU Emacs packages. In order to have syntax highlight and other features¹, use the following on your configuration file:

(use-package treesit
  :preface
  (dolist (mapping '((go-mode . go-ts-mode)))
    (add-to-list 'major-mode-remap-alist mapping))
  :init
  (add-to-list 'auto-mode-alist '("\\.go\\'" . go-ts-mode))
  (add-to-list 'auto-mode-alist '("/go\\.mod\\'" . go-mod-ts-mode)))

For the LSP client, you can write the following to automatically connect to gopls when you open a Go file:

(use-package eglot
  :hook ((go-ts-mode . eglot-ensure))

This should be enough to give you LSP support, syntax highlighting and error diagnostics. All of this already bundled on GNU Emacs!