vim-patch:8.2.4156: fileinfo message overwrites echo'ed message

Problem:    Fileinfo message overwrites echo'ed message.
Solution:   Reset need_fileinfo when displaying a message. (Rob Pilling,
            closes vim/vim#9569)
726f7f91fd

src/nvim/message.c

@@ -327,11 +327,12 @@ bool msg_attr_keep(const char *s, int attr, bool keep, bool multiline)
   }
   retval = msg_end();
 
-  if (keep && retval && vim_strsize((char_u *)s) < (Rows - cmdline_row - 1)
-      * Columns + sc_col) {
+  if (keep && retval && vim_strsize((char_u *)s) < (Rows - cmdline_row - 1) * Columns + sc_col) {
     set_keep_msg((char *)s, 0);
   }
 
+  need_fileinfo = false;
+
   xfree(buf);
   --entered;
   return retval;
@@ -1355,6 +1356,7 @@ void msg_start(void)
 
   if (!msg_silent) {
     XFREE_CLEAR(keep_msg);              // don't display old message now
+    need_fileinfo = false;
   }
 
   if (need_clr_eos) {
@@ -2026,6 +2028,8 @@ void msg_puts_attr_len(const char *const str, const ptrdiff_t len, int attr)
   if (!msg_use_printf() || (headless_mode && default_grid.chars)) {
     msg_puts_display((const char_u *)str, len, attr, false);
   }
+
+  need_fileinfo = false;
 }
 
 /// Print a formatted message

src/nvim/testdir/test_messages.vim

@@ -135,3 +135,35 @@ func Test_echo_string_partial()
   call assert_equal("function('CountSpaces', [{'ccccccccccc': ['ab', 'cd'], 'aaaaaaaaaaa': v:false, 'bbbbbbbbbbbb': ''}])", string(function('CountSpaces', [#{aaaaaaaaaaa: v:false, bbbbbbbbbbbb: '', ccccccccccc: ['ab', 'cd']}])))
 endfunc
 
+" Message output was previously overwritten by the fileinfo display, shown
+" when switching buffers. If a buffer is switched to, then a message if
+" echoed, we should show the message, rather than overwriting it with
+" fileinfo.
+func Test_fileinfo_after_echo()
+  CheckScreendump
+
+  let content =<< trim END
+    file a.txt
+
+    hide edit b.txt
+    call setline(1, "hi")
+    setlocal modified
+
+    hide buffer a.txt
+
+    set updatetime=1
+    autocmd CursorHold * b b.txt | w | echo "'b' written"
+  END
+
+  call writefile(content, 'Xtest_fileinfo_after_echo')
+  let buf = RunVimInTerminal('-S Xtest_fileinfo_after_echo', #{rows: 6})
+  call VerifyScreenDump(buf, 'Test_fileinfo_after_echo', {})
+
+  call term_sendkeys(buf, ":q\<CR>")
+
+  " clean up
+  call StopVimInTerminal(buf)
+  call delete('Xtest_fileinfo_after_echo')
+endfunc
+
+" vim: shiftwidth=2 sts=2 expandtab

test/functional/legacy/messages_spec.lua

@@ -2,6 +2,7 @@ local helpers = require('test.functional.helpers')(after_each)
 local Screen = require('test.functional.ui.screen')
 local clear = helpers.clear
 local command = helpers.command
+local exec = helpers.exec
 local feed = helpers.feed
 
 before_each(clear)
@@ -35,4 +36,34 @@ describe('messages', function()
                                               |
     ]])
   end)
+
+  it('fileinfo does not overwrite echo message vim-patch:8.2.4156', function()
+    local screen = Screen.new(40, 6)
+    screen:set_default_attr_ids({
+      [1] = {bold = true, foreground = Screen.colors.Blue},  -- NonText
+    })
+    screen:attach()
+    exec([[
+      set shortmess-=F
+
+      file a.txt
+
+      hide edit b.txt
+      call setline(1, "hi")
+      setlocal modified
+
+      hide buffer a.txt
+
+      set updatetime=1
+      autocmd CursorHold * b b.txt | w | echo "'b' written"
+    ]])
+    screen:expect([[
+      ^hi                                      |
+      {1:~                                       }|
+      {1:~                                       }|
+      {1:~                                       }|
+      {1:~                                       }|
+      'b' written                             |
+    ]])
+  end)
 end)