`zig build` on save with `ALE`

init.vim

  " zig ALE linter by fubd @ FreeNode
  " Author: Kevin Watters <[email protected]>
  " Description: This file adds support for checking zig code.
  "
  
  let g:ale_lint_on_text_changed = 'never'
  let g:ale_zig_compiler = "zig"
  
  function! ZigGetExecutable(buffer) abort
      return g:ale_zig_compiler
  endfunction
  
  function! s:find_build_dir(direc, count) abort
      let l:path = a:direc . "/build.zig"
      if filereadable(l:path)
          return a:direc
      else
          if a:count < 10
              return s:find_build_dir(expand(a:direc . "../"), a:count + 1)
          endif
      endif 
  
      return "."
  endif
  
  endfunction
  
  function! ZigGetCommand(buffer) abort
      let l:buf_direc = expand('%:h')
      let l:direc = s:find_build_dir(l:buf_direc, 0)
  
      return 'cd ' . direc . ' && ' . fnameescape(ZigGetExecutable(a:buffer))
      \   . ' build --verbose'
  endfunction
  
  function! ZigHandleZigCompilerCheck(buffer, lines) abort
      " Regular expression to match messages:
      " They look like:
      "
      " C:\Users\Foo\src\myproject\src\main.zig:24:4: error: invalid token: '.'
      "
      let l:pattern = '\v([^\(]+):(\d+):(\d+): error: (.*)$'
  
      let l:output = [] " For each match, update the l:output list:
  
      for l:match in ale#util#GetMatches(a:lines, l:pattern)
          call add(l:output, {
          \   'filename': expand(l:match[1]),
          \   'lnum': str2nr(l:match[2]),
          \   'col': str2nr(l:match[3]),
          \   'text': l:match[4],
          \   'type': 'E'
          \})
      endfor
  
      return l:output
  endfunction
  
  call ale#linter#Define('zig', {
  \   'name': 'zigbuild',
  \   'executable_callback': 'ZigGetExecutable',
  \   'command_callback': 'ZigGetCommand',
  \   'callback': 'ZigHandleZigCompilerCheck',
  \   'output_stream': 'both'
  \})
  
  " zig bindings
  augroup filetype_zig
    autocmd FileType zig nnoremap <buffer> <leader>en :ALENextWrap<CR>
    autocmd FileType zig nnoremap <buffer> <leader>ep :ALEPreviousWrap<CR>
    autocmd FileType zig nnoremap <silent> <localleader>= :call zig#fmt#Format()<CR>
  augroup END