conform: disable autoformat on save for specified filetypes

Provide a method to disable autoformat on save for specified
filetypes. By default disable for C/C++ as an example, because
it does not have a well standardized coding style.

Based on conform recipe:
https://github.com/stevearc/conform.nvim/blob/master/doc/recipes.md

Author: dam9000

init.lua

@@ -603,10 +603,19 @@ require('lazy').setup({
     'stevearc/conform.nvim',
     opts = {
       notify_on_error = false,
-      format_on_save = {
-        timeout_ms = 500,
-        lsp_fallback = true,
-      },
+      format_on_save = function(bufnr)
+        -- Disable "autoformat on save" 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', 'cpp' }
+        if vim.tbl_contains(disable_filetypes, vim.bo[bufnr].filetype) then
+          return
+        end
+        return {
+          timeout_ms = 500,
+          lsp_fallback = true,
+        }
+      end,
       formatters_by_ft = {
         lua = { 'stylua' },
         -- Conform can also run multiple formatters sequentially