fix: show autocmd output when F is in shortmess (#18251)

The default value of including F in 'shortmess' has the unfortunate side
effect of hiding output from autocommands. This is a common source of
confusion and often leads people to think their autocommands are not
working when they are. There is a small snippet in the docs for
'shortmess' indicating that the F flag suppresses autocmd output, but
it's not easy to find if you don't already know to look for it.

This commit removes that behavior of the F flag to make it only suppress
file info when opening a new file.

runtime/doc/options.txt

@@ -5532,8 +5532,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 		"Pattern not found", "Back at original", etc.
 	  q	use "recording" instead of "recording @a"
 	  F	don't give the file info when editing a file, like `:silent`
-		was used for the command; note that this also affects messages
+		was used for the command
-		from autocommands
 	  S     do not show search count message when searching, e.g.
 	        "[1/5]"
 

runtime/doc/vim_diff.txt

@@ -375,6 +375,7 @@ Normal commands:
 Options:
   'ttimeout', 'ttimeoutlen' behavior was simplified
   |jumpoptions| "stack" behavior
+  'shortmess' the "F" flag does not affect output from autocommands
 
 Shell:
   Shell output (|:!|, |:make|, …) is always routed through the UI, so it

src/nvim/buffer.c

@@ -109,6 +109,7 @@ static int read_buffer(int read_stdin, exarg_T *eap, int flags)
 {
   int retval = OK;
   linenr_T line_count;
+  bool silent = shortmess(SHM_FILEINFO);
 
   // Read from the buffer which the text is already filled in and append at
   // the end.  This makes it possible to retry when 'fileformat' or
@@ -117,7 +118,7 @@ static int read_buffer(int read_stdin, exarg_T *eap, int flags)
   retval = readfile(read_stdin ? NULL : curbuf->b_ffname,
                     read_stdin ? NULL : curbuf->b_fname,
                     line_count, (linenr_T)0, (linenr_T)MAXLNUM, eap,
-                    flags | READ_BUFFER);
+                    flags | READ_BUFFER, silent);
   if (retval == OK) {
     // Delete the binary lines.
     while (--line_count >= 0) {
@@ -162,6 +163,7 @@ int open_buffer(int read_stdin, exarg_T *eap, int flags)
   bufref_T old_curbuf;
   long old_tw = curbuf->b_p_tw;
   int read_fifo = false;
+  bool silent = shortmess(SHM_FILEINFO);
 
   // The 'readonly' flag is only set when BF_NEVERLOADED is being reset.
   // When re-entering the same buffer, it should not change, because the
@@ -212,7 +214,6 @@ int open_buffer(int read_stdin, exarg_T *eap, int flags)
   curwin->w_valid = 0;
 
   if (curbuf->b_ffname != NULL) {
-    int old_msg_silent = msg_silent;
 #ifdef UNIX
     int save_bin = curbuf->b_p_bin;
     int perm;
@@ -231,13 +232,10 @@ int open_buffer(int read_stdin, exarg_T *eap, int flags)
       curbuf->b_p_bin = true;
     }
 #endif
-    if (shortmess(SHM_FILEINFO)) {
-      msg_silent = 1;
-    }
 
     retval = readfile(curbuf->b_ffname, curbuf->b_fname,
                       (linenr_T)0, (linenr_T)0, (linenr_T)MAXLNUM, eap,
-                      flags | READ_NEW | (read_fifo ? READ_FIFO : 0));
+                      flags | READ_NEW | (read_fifo ? READ_FIFO : 0), silent);
 #ifdef UNIX
     if (read_fifo) {
       curbuf->b_p_bin = save_bin;
@@ -246,7 +244,6 @@ int open_buffer(int read_stdin, exarg_T *eap, int flags)
       }
     }
 #endif
-    msg_silent = old_msg_silent;
 
     // Help buffer is filtered.
     if (bt_help(curbuf)) {
@@ -262,7 +259,7 @@ int open_buffer(int read_stdin, exarg_T *eap, int flags)
     curbuf->b_p_bin = true;
     retval = readfile(NULL, NULL, (linenr_T)0,
                       (linenr_T)0, (linenr_T)MAXLNUM, NULL,
-                      flags | (READ_NEW + READ_STDIN));
+                      flags | (READ_NEW + READ_STDIN), silent);
     curbuf->b_p_bin = save_bin;
     if (retval == OK) {
       retval = read_buffer(true, eap, flags);
@@ -903,14 +900,7 @@ void handle_swap_exists(bufref_T *old_curbuf)
       buf = old_curbuf->br_buf;
     }
     if (buf != NULL) {
-      int old_msg_silent = msg_silent;
-
-      if (shortmess(SHM_FILEINFO)) {
-        msg_silent = 1;  // prevent fileinfo message
-      }
       enter_buffer(buf);
-      // restore msg_silent, so that the command line will be shown
-      msg_silent = old_msg_silent;
 
       if (old_tw != curbuf->b_p_tw) {
         check_colorcolumn(curwin);
@@ -5611,7 +5601,7 @@ bool buf_contents_changed(buf_T *buf)
   if (ml_open(curbuf) == OK
       && readfile(buf->b_ffname, buf->b_fname,
                   (linenr_T)0, (linenr_T)0, (linenr_T)MAXLNUM,
-                  &ea, READ_NEW | READ_DUMMY) == OK) {
+                  &ea, READ_NEW | READ_DUMMY, false) == OK) {
     // compare the two files line by line
     if (buf->b_ml.ml_line_count == curbuf->b_ml.ml_line_count) {
       differ = false;

src/nvim/ex_cmds.c

@@ -1387,7 +1387,7 @@ static void do_filter(linenr_T line1, linenr_T line2, exarg_T *eap, char_u *cmd,
   if (do_out) {
     if (otmp != NULL) {
       if (readfile(otmp, NULL, line2, (linenr_T)0, (linenr_T)MAXLNUM, eap,
-                   READ_FILTER) != OK) {
+                   READ_FILTER, false) != OK) {
         if (!aborting()) {
           msg_putchar('\n');
           semsg(_(e_notread), otmp);

src/nvim/ex_docmd.c

@@ -7702,13 +7702,13 @@ static void ex_read(exarg_T *eap)
         return;
       }
       i = readfile(curbuf->b_ffname, curbuf->b_fname,
-                   eap->line2, (linenr_T)0, (linenr_T)MAXLNUM, eap, 0);
+                   eap->line2, (linenr_T)0, (linenr_T)MAXLNUM, eap, 0, false);
     } else {
       if (vim_strchr(p_cpo, CPO_ALTREAD) != NULL) {
         (void)setaltfname(eap->arg, eap->arg, (linenr_T)1);
       }
       i = readfile(eap->arg, NULL,
-                   eap->line2, (linenr_T)0, (linenr_T)MAXLNUM, eap, 0);
+                   eap->line2, (linenr_T)0, (linenr_T)MAXLNUM, eap, 0, false);
     }
     if (i != OK) {
       if (!aborting()) {

src/nvim/fileio.c

@@ -176,7 +176,7 @@ void filemess(buf_T *buf, char_u *name, char_u *s, int attr)
 ///
 /// @return     FAIL for failure, NOTDONE for directory (failure), or OK
 int readfile(char_u *fname, char_u *sfname, linenr_T from, linenr_T lines_to_skip,
-             linenr_T lines_to_read, exarg_T *eap, int flags)
+             linenr_T lines_to_read, exarg_T *eap, int flags, bool silent)
 {
   int fd = 0;
   int newfile = (flags & READ_NEW);
@@ -472,11 +472,13 @@ int readfile(char_u *fname, char_u *sfname, linenr_T from, linenr_T lines_to_ski
           return FAIL;
         }
       }
+      if (!silent) {
         if (dir_of_file_exists(fname)) {
           filemess(curbuf, sfname, (char_u *)new_file_message(), 0);
         } else {
           filemess(curbuf, sfname, (char_u *)_("[New DIRECTORY]"), 0);
         }
+      }
       // Even though this is a new file, it might have been
       // edited before and deleted.  Get the old marks.
       check_marks_read();
@@ -658,7 +660,7 @@ int readfile(char_u *fname, char_u *sfname, linenr_T from, linenr_T lines_to_ski
   // Autocommands may add lines to the file, need to check if it is empty
   wasempty = (curbuf->b_ml.ml_flags & ML_EMPTY);
 
-  if (!recoverymode && !filtering && !(flags & READ_DUMMY)) {
+  if (!recoverymode && !filtering && !(flags & READ_DUMMY) && !silent) {
     if (!read_stdin && !read_buffer) {
       filemess(curbuf, sfname, (char_u *)"", 0);
     }
@@ -1788,7 +1790,7 @@ failed:
       return OK;                // an interrupt isn't really an error
     }
 
-    if (!filtering && !(flags & READ_DUMMY)) {
+    if (!filtering && !(flags & READ_DUMMY) && !silent) {
       add_quoted_fname((char *)IObuff, IOSIZE, curbuf, (const char *)sfname);
       c = false;
 
@@ -5191,7 +5193,7 @@ void buf_reload(buf_T *buf, int orig_mode, bool reload_options)
     curbuf->b_flags |= BF_CHECK_RO;           // check for RO again
     keep_filetype = true;                     // don't detect 'filetype'
     if (readfile(buf->b_ffname, buf->b_fname, (linenr_T)0, (linenr_T)0,
-                 (linenr_T)MAXLNUM, &ea, flags) != OK) {
+                 (linenr_T)MAXLNUM, &ea, flags, false) != OK) {
       if (!aborting()) {
         semsg(_("E321: Could not reload \"%s\""), buf->b_fname);
       }

src/nvim/memline.c

@@ -994,7 +994,7 @@ void ml_recover(bool checkext)
    */
   if (curbuf->b_ffname != NULL) {
     orig_file_status = readfile(curbuf->b_ffname, NULL, (linenr_T)0,
-                                (linenr_T)0, (linenr_T)MAXLNUM, NULL, READ_NEW);
+                                (linenr_T)0, (linenr_T)MAXLNUM, NULL, READ_NEW, false);
   }
 
   // Use the 'fileformat' and 'fileencoding' as stored in the swap file.
@@ -1069,7 +1069,7 @@ void ml_recover(bool checkext)
               line_count = pp->pb_pointer[idx].pe_line_count;
               if (readfile(curbuf->b_ffname, NULL, lnum,
                            pp->pb_pointer[idx].pe_old_lnum - 1, line_count,
-                           NULL, 0) != OK) {
+                           NULL, 0, false) != OK) {
                 cannot_open = true;
               } else {
                 lnum += line_count;

src/nvim/quickfix.c

@@ -5753,7 +5753,7 @@ static buf_T *load_dummy_buffer(char_u *fname, char_u *dirname_start, char_u *re
     newbuf_to_wipe.br_buf = NULL;
     readfile_result = readfile(fname, NULL, (linenr_T)0, (linenr_T)0,
                                (linenr_T)MAXLNUM, NULL,
-                               READ_NEW | READ_DUMMY);
+                               READ_NEW | READ_DUMMY, false);
     newbuf->b_locked--;
     if (readfile_result == OK
         && !got_int