vim-patch:8.1.0161: buffer not updated with 'autoread' set if file was deleted

Problem:    Buffer not updated with 'autoread' set if file was deleted.
            (Michael Naumann)
Solution:   Don't set the timestamp to zero. (closes vim/vim#3165)
386bc82a3f

Sleep 2 seconds for autoread (https://github.com/neovim/neovim/pull/7592).

src/nvim/fileio.c

@@ -4892,10 +4892,12 @@ buf_check_timestamp (
           )) {
     retval = 1;
 
-    /* set b_mtime to stop further warnings (e.g., when executing
+    // set b_mtime to stop further warnings (e.g., when executing
-     * FileChangedShell autocmd) */
+    // FileChangedShell autocmd)
     if (!file_info_ok) {
-      buf->b_mtime = 0;
+      // When 'autoread' is set we'll check the file again to see if it
+      // re-appears.
+      buf->b_mtime = buf->b_p_ar;
       buf->b_orig_size = 0;
       buf->b_orig_mode = 0;
     } else {

src/nvim/testdir/test_stat.vim

@@ -46,6 +46,15 @@ func Test_existent_directory()
   call assert_equal('rwx', getfperm(dname)[0:2])
 endfunc
 
+func SleepForTimestamp()
+  " FAT has a granularity of 2 seconds, otherwise it's usually 1 second
+  if has('win32')
+    sleep 2
+  else
+    sleep 2
+  endif
+endfunc
+
 func Test_checktime()
   let fname = 'Xtest.tmp'
 
@@ -53,12 +62,7 @@ func Test_checktime()
   call writefile(fl, fname)
   set autoread
   exec 'e' fname
-  " FAT has a granularity of 2 seconds, otherwise it's usually 1 second
+  call SleepForTimestamp()
-  if has('win32')
-    sleep 2
-  else
-    sleep 2
-  endif
   let fl = readfile(fname)
   let fl[0] .= ' - checktime'
   call writefile(fl, fname)
@@ -68,6 +72,46 @@ func Test_checktime()
   call delete(fname)
 endfunc
 
+func Test_autoread_file_deleted()
+  new Xautoread
+  set autoread
+  call setline(1, 'original')
+  w!
+
+  call SleepForTimestamp()
+  if has('win32')
+    silent !echo changed > Xautoread
+  else
+    silent !echo 'changed' > Xautoread
+  endif
+  checktime
+  call assert_equal('changed', trim(getline(1)))
+
+  call SleepForTimestamp()
+  messages clear
+  if has('win32')
+    silent !del Xautoread
+  else
+    silent !rm Xautoread
+  endif
+  checktime
+  call assert_match('E211:', execute('messages'))
+  call assert_equal('changed', trim(getline(1)))
+
+  call SleepForTimestamp()
+  if has('win32')
+    silent !echo recreated > Xautoread
+  else
+    silent !echo 'recreated' > Xautoread
+  endif
+  checktime
+  call assert_equal('recreated', trim(getline(1)))
+
+  call delete('Xautoread')
+  bwipe!
+endfunc
+
+
 func Test_nonexistent_file()
   let fname = 'Xtest.tmp'