OK, I think I've actually come up with an answer to my own question.
Firstly, I generate two tags files: tags_c_vim and tags_c_omni.
In my _vimrc I have:
let tags_vim='tags_c_vim'
let tags_omni='tags_c_omni'
exe "set tags=".tags_vim
to setup some variables pointing to the different tags files, and to set the "vim" tags to be the default tags.
Then I also have this, again in the _vimrc:
imap <F8> <ESC>:exe "set tags=".tags_omni<CR>a<C-X><C-O>
autocmd InsertLeave * if pumvisible() == 0|exe "set tags=".tags_vim|endif
the first line here maps F8 so it changes the tags setting to point to the "omni" tags before then invoking the omnicomplete popup menu, and the second line resets the tags setting to the "vim" tags when insert mode is next left after the popup has closed.
It's going to need some extensive use to make sure it's robust enough, but it does seem to work after some quick testing.
Two improvements I'd still like to make:
- Map the setting of the "omni" tags to the omnicomplete C-X,C-O command instead of a new F8 mapping. (I think I need to set the tags and then call omni#cpp#maycomplete#Complete(), but I couldn't work out how to do this)
- Hook the resetting of the "vim" tags into either omnicomplete itself finishing or the popup menu closing
Anyway, I just thought I'd share.
Cheers,
thoughton.