vim cannot fold cpp and golang code

vim cannot fold test.cpp, vim prompts E490 no fold found, but rename this file to test.c or test.cc, vim can use zc to fold this same code.

I have set configure in .vimrc foldmethod=syntax set foldlevel=0 set foldnestmax=2 VIMRUNTIME=/usr/share/vim/vim80

in /usr/share/vim/vim80/ftplugin, there exits a cpp.vim file. 

why vim cannot fold *.cpp and *.go, any problem?

--
--
You received this message from the "vim_use" maillist.
Do not top-post! Type your reply below the text you are replying to.
For more information, visit http://www.vim.org/maillist.php

---
You received this message because you are subscribed to the Google Groups "vim_use" group.
To unsubscribe from this group and stop receiving emails from it, send an email to vim_use+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.