patch 8.2.2900: QuitPre is triggered before :wq writes the file

Problem:    QuitPre is triggered before :wq writes the file, which is
            different from other commands.
Solution:   Trigger QuitPre after writing the file. (closes #8279)

src/ex_docmd.c

@@ -6089,7 +6089,7 @@ ex_stop(exarg_T *eap)
 }
 
 /*
- * ":exit", ":xit" and ":wq": Write file and quite the current window.
+ * ":exit", ":xit" and ":wq": Write file and quit the current window.
  */
     static void
 ex_exit(exarg_T *eap)
@@ -6112,17 +6112,17 @@ ex_exit(exarg_T *eap)
 	return;
     }
 
-    if (before_quit_autocmds(curwin, FALSE, eap->forceit))
-	return;
-
     /*
-     * if more files or windows we won't exit
+     * we plan to exit if there is only one relevant window
      */
     if (check_more(FALSE, eap->forceit) == OK && only_one_window())
 	exiting = TRUE;
-    if (       ((eap->cmdidx == CMD_wq
+
-		    || curbufIsChanged())
+    // Write the buffer for ":wq" or when it was changed.
-		&& do_write(eap) == FAIL)
+    // Trigger QuitPre and ExitPre.
+    // Check if we can exit now, after autocommands have changed things.
+    if (((eap->cmdidx == CMD_wq || curbufIsChanged()) && do_write(eap) == FAIL)
+	    || before_quit_autocmds(curwin, FALSE, eap->forceit)
 	    || check_more(TRUE, eap->forceit) == FAIL
 	    || (only_one_window() && check_changed_any(eap->forceit, FALSE)))
     {

src/testdir/test_writefile.vim

@@ -915,4 +915,25 @@ func Test_write_binary_file()
   call delete('Xfile3')
 endfunc
 
+" Check that buffer is written before triggering QuitPre
+func Test_wq_quitpre_autocommand()
+  edit Xsomefile
+  call setline(1, 'hello')
+  split
+  let g:seq = []
+  augroup Testing
+    au QuitPre * call add(g:seq, 'QuitPre - ' .. (&modified ? 'modified' : 'not modified'))
+    au BufWritePost * call add(g:seq, 'written')
+  augroup END
+  wq
+  call assert_equal(['written', 'QuitPre - not modified'], g:seq)
+
+  augroup Testing
+    au!
+  augroup END
+  bwipe!
+  unlet g:seq
+  call delete('Xsomefile')
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2900,
 /**/
     2899,
 /**/