#2017 Add support for display results from other sources

autoload/ale.vim

@@ -94,6 +94,11 @@ function! s:Lint(buffer, should_lint_file, timer_id) abort
     \   ? ale#engine#ignore#Exclude(l:filetype, l:linters, l:ignore_config)
     \   : l:linters
 
+    " Tell other sources that they can start checking the buffer now.
+    let g:ale_want_results_buffer = a:buffer
+    silent doautocmd <nomodeline> User ALEWantResults
+    unlet! g:ale_want_results_buffer
+
     " Don't set up buffer data and so on if there are no linters to run.
     if !has_key(g:ale_buffer_info, a:buffer) && empty(l:linters)
         return