Refactor conform config

- Change `format_on_save` to a blacklist
- Use stylua's lsp for formatting instead of its CLI

See nvim-lua/kickstart.nvim#1991

Author: joshjavier

dot_config/nvim/init.lua

@@ -398,6 +398,8 @@ require('lazy').setup({
         -- Special Lua Config, as recommended by neovim help docs
         lua_ls = {
           on_init = function(client)
+            client.server_capabilities.documentFormattingProvider = false -- Disable formatting (formatting is done by stylua)
+
             if client.workspace_folders then
               local path = client.workspace_folders[1].name
               if path ~= vim.fn.stdpath 'config' and (vim.uv.fs_stat(path .. '/.luarc.json') or vim.uv.fs_stat(path .. '/.luarc.jsonc')) then return end
@@ -420,8 +422,11 @@ require('lazy').setup({
               },
             })
           end,
+          ---@type lspconfig.settings.lua_ls
           settings = {
-            Lua = {},
+            Lua = {
+              format = { enable = false }, -- Disable formatting (formatting is done by stylua)
+            },
           },
         },
 
@@ -472,7 +477,7 @@ require('lazy').setup({
     keys = {
       {
         '<leader>f',
-        function() require('conform').format { async = true, lsp_format = 'fallback' } end,
+        function() require('conform').format { async = true } end,
         mode = '',
         desc = '[F]ormat buffer',
       },
@@ -482,21 +487,23 @@ require('lazy').setup({
     opts = {
       notify_on_error = false,
       format_on_save = function(bufnr)
-        -- Disable "format_on_save lsp_fallback" for languages that don't
-        -- have a well standardized coding style. You can add additional
-        -- languages here or re-enable it for the disabled ones.
-        local disable_filetypes = { c = true, cpp = true }
-        if disable_filetypes[vim.bo[bufnr].filetype] then
-          return nil
+        -- You can specify filetypes to autoformat on save here:
+        local enabled_filetypes = {
+          lua = true,
+          python = true,
+        }
+        if enabled_filetypes[vim.bo[bufnr].filetype] then
+          return { timeout_ms = 500 }
         else
-          return {
-            timeout_ms = 500,
-            lsp_format = 'fallback',
-          }
+          return nil
         end
       end,
+      default_format_opts = {
+        lsp_format = 'fallback', -- Use external formatters if configured below, otherwise use LSP formatting. Set to `false` to disable LSP formatting entirely.
+      },
+      -- You can also specify external formatters in here.
       formatters_by_ft = {
-        lua = { 'stylua' },
+        -- rust = { 'rustfmt' },
         sh = { 'shfmt' },
         -- Conform can also run multiple formatters sequentially
         -- python = { "isort", "black" },