filetype setting lost after reloading all files in buffer

Question

After running :bufdo e! All my files lose their filetype setting and I have to manually run :set ft=XXX in each file.

Anyone know how to so

Answer 1

You can fix this automatically via the following autocmd:

" Enable syntax highlighting when buffers were loaded through :bufdo, which
" disables the Syntax autocmd event to speed up processing.
augroup EnableSyntaxHighlighting
    " Filetype processing does happen, so we can detect a buffer initially
    " loaded during :bufdo through a set filetype, but missing b:current_syntax.
    " Also don't do this when the user explicitly turned off syntax highlighting
    " via :syntax off.
    " Note: Must allow nesting of autocmds so that the :syntax enable triggers
    " the ColorScheme event. Otherwise, some highlighting groups may not be
    " restored properly.
    autocmd! BufWinEnter * nested if exists('syntax_on') && ! exists('b:current_syntax') && ! empty(&l:filetype) | syntax enable | endif

    " The above does not handle reloading via :bufdo edit!, because the
    " b:current_syntax variable is not cleared by that. During the :bufdo,
    " 'eventignore' contains "Syntax", so this can be used to detect this
    " situation when the file is re-read into the buffer. Due to the
    " 'eventignore', an immediate :syntax enable is ignored, but by clearing
    " b:current_syntax, the above handler will do this when the reloaded buffer
    " is displayed in a window again.
    autocmd! BufRead * if exists('syntax_on') && exists('b:current_syntax') && ! empty(&l:filetype) && index(split(&eventignore, ','), 'Syntax') != -1 | unlet! b:current_syntax | endif
augroup END

Edit: Add autocmd nesting for proper restore of highlight groups and handle buffer reloads, as the question explicitly asked for this.