nvim: use icons for diagnostics

.config/nvim/lua/my/coding.lua

@@ -81,3 +81,10 @@ require('project_nvim').setup({
     show_hidden = false,
     fallback_buffer_dir = true
 })
+
+-- icons for diagnostics in the symbol column
+local signs = { Error = " ", Warn = " ", Hint = " ", Info = " " }
+for type, icon in pairs(signs) do
+    local hl = "DiagnosticSign" .. type
+    vim.fn.sign_define(hl, { text = icon, texthl = hl, numhl = hl })
+end