YouCompleteme works but can not complete using TAB

Question

I installed YouCompleteMe using vundle. Then installed all plugins and installed YCM using

./install.sh --clang-completer

This is how my vimrc looks:

syntax on
set expandtab
set cindent
set tabstop=4
retab
set shiftwidth=4
set hlsearch
set paste
set ic
set number
colorscheme molokai
set t_Co=256

set nocompatible              " be iMproved, required
filetype off                  " required

" set the runtime path to include Vundle and initialize
set rtp+=~/.vim/bundle/Vundle.vim
call vundle#begin()

Plugin 'gmarik/Vundle.vim'
Plugin 'tpope/vim-fugitive'
Plugin 'tpope/vim-repeat' 
Plugin 'kien/ctrlp.vim'
Plugin 'sjl/gundo.vim'
Plugin 'Valloric/YouCompleteMe'
Plugin 'scrooloose/syntastic'
Plugin 'Valloric/ListToggle'

call vundle#end()            " required


filetype plugin indent on 

"options for syntastic"

set statusline+=%#warningmsg#
set statusline+=%{SyntasticStatuslineFlag()}
set statusline+=%*
let g:syntastic_python_checkers=['pep8', 'pylint', 'python']
let g:syntastic_enable_signs=1
let g:syntastic_auto_loc_list=1
let g:syntastic_check_on_open = 1
let g:syntastic_check_on_wq = 1
let g:syntastic_error_symbol = "X"
let g:syntastic_style_error_symbol = ">"
let g:syntastic_warning_symbol = "!"
let g:syntastic_style_warning_symbol = ">"
let g:syntastic_echo_current_error=1
let g:syntastic_enable_balloons = 1
let g:syntastic_auto_jump=1

"Gundo options"

nnoremap <F5> :GundoToggle<CR>

"CtrlP options"
let g:ctrlp_map = '<c-p>'
let g:ctrlp_cmd = 'CtrlP'

"Powerline stuff"
python from powerline.vim import setup as powerline_setup
python powerline_setup()
python del powerline_setup

set laststatus=2

YCM works but I can't switch between the suggestions using TAB, only using Down and Up arrows and accepting with Enter.

Why is happening this? Is another program using the TAB key?

thanks a lot for the help

Answer 1

By configuring set paste, you're effectively disabling all mappings and abbreviations.

You only need that set when you actually paste text in terminal Vim! It's best to bind this to a key. As mappings cannot be used when the option is set, Vim provides a special option for this:

:set pastetoggle=<F10>

Further commentary

As the ~/.vimrc is sourced at the beginning of Vim startup (when files passed to it haven't yet been loaded), the retab is ineffective; just drop it. If you really want automatic reindenting for opened files, you'd have to employ an :autocmd BufRead * retab for that, but I'd advise against that.

Answer 2

The problem was due to the "set paste" line in my .vimrc

so, I removed it, and when I want to paste large blocks of code in vim, I just write :set paste to enable it or :set nopaste to disable it. This toggle can be also mapped to f10 or any key.