commit https://github.com/vim/vim/commit/46643713dc6bb04b4e84986b1763ef309e960161 Author: Bram Moolenaar <Bram@vim.org> Date: Fri Sep 9 21:42:36 2016 +0200 patch 7.4.2357 Problem: Attempt to read history entry while not initialized. Solution: Skip when the index is negative.

" Vim filetype plugin file
" Language:	C++
" Maintainer:	Bram Moolenaar <Bram@vim.org>
" Last Change:	2001 Jan 15

" Only do this when not done yet for this buffer
if exists("b:did_ftplugin")
  finish
endif

" Behaves just like C
runtime! ftplugin/c.vim ftplugin/c_*.vim ftplugin/c/*.vim