Change latex provider to luatex, closes #476

autoload/vimtex/parser/auxiliary.vim

@@ -0,0 +1,58 @@
+if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'latex') == -1
+
+" vimtex - LaTeX plugin for Vim
+"
+" Maintainer: Karl Yngve Lervåg
+" Email:      karl.yngve@gmail.com
+"
+
+function! vimtex#parser#auxiliary#parse(file) abort " {{{1
+  return s:parse_recurse(a:file, [])
+endfunction
+
+" }}}1
+
+function! s:parse_recurse(file, parsed) abort " {{{1
+  if !filereadable(a:file) || index(a:parsed, a:file) >= 0
+    return []
+  endif
+  call add(a:parsed, a:file)
+
+  let l:lines = []
+  for l:line in readfile(a:file)
+    call add(l:lines, l:line)
+
+    if l:line =~# '\\@input{'
+      let l:file = s:input_line_parser(l:line, a:file)
+      call extend(l:lines, s:parse_recurse(l:file, a:parsed))
+    endif
+  endfor
+
+  return l:lines
+endfunction
+
+" }}}1
+
+function! s:input_line_parser(line, file) abort " {{{1
+  let l:file = matchstr(a:line, '\\@input{\zs[^}]\+\ze}')
+
+  " Remove extension to simplify the parsing (e.g. for "my file name".aux)
+  let l:file = substitute(l:file, '\.aux', '', '')
+
+  " Trim whitespaces and quotes from beginning/end of string, append extension
+  let l:file = substitute(l:file, '^\(\s\|"\)*', '', '')
+  let l:file = substitute(l:file, '\(\s\|"\)*$', '', '')
+  let l:file .= '.aux'
+
+  " Use absolute paths
+  if l:file !~# '\v^(\/|[A-Z]:)'
+    let l:file = fnamemodify(a:file, ':p:h') . '/' . l:file
+  endif
+
+  " Only return filename if it is readable
+  return filereadable(l:file) ? l:file : ''
+endfunction
+
+" }}}1
+
+endif