fix(messages): "progress" kind for busy messages #39280

Problem:  The "Scanning:" completion, bufwrite, and indent (there may be
          more) messages which indicate progress can use the "progress" kind
          for their msg_show event. Indent message does not have a kind.

Solution: Emit these messages with the "progress" kind. Set the message id
          to the replaced kind so that a UI knows to replace it (and to provide
          a migration path in case a UI was distinguishing these messages for
          whatever reason).

5 files changed, 48 insertions, 30 deletions

diff --git a/src/nvim/bufwrite.c b/src/nvim/bufwrite.c
index f45d01a289..4a14a1ecb2 100644
--- a/src/nvim/bufwrite.c
+++ b/src/nvim/bufwrite.c
@@ -1081,7 +1081,6 @@ int buf_write(buf_T *buf, char *fname, char *sfname, linenr_T start, linenr_T en
     msg_scroll = true;              // don't overwrite previous file message
   }
   if (!filtering) {
-    msg_ext_set_kind("bufwrite");
     // show that we are busy
 #ifndef UNIX
     filemess(buf, sfname, "");
@@ -1708,10 +1707,7 @@ restore_backup:
         xstrlcat(IObuff, shortmess(SHM_WRI) ? _(" [w]") : _(" written"), IOSIZE);
       }
     }
-
-    msg_ext_set_kind("bufwrite");
-    msg_ext_overwrite = true;
-    set_keep_msg(msg_trunc(IObuff, false, 0), 0);
+    set_keep_msg(msg_progress(IObuff, "bufwrite", "success", 0, true, true), 0);
   }
 
   // When written everything correctly: reset 'modified'.  Unless not
diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index 5b659cb91d..69a9ba0e2d 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -131,9 +131,12 @@ void filemess(buf_T *buf, char *name, char *s)
   msg_scroll = msg_scroll_save;
   msg_scrolled_ign = true;
   // may truncate the message to avoid a hit-return prompt
-  msg_outtrans(msg_may_trunc(false, IObuff), 0, false);
+  if (*s == NUL) {
+    msg_progress(IObuff, "bufwrite", "running", 0, false, true);
+  } else {
+    msg_outtrans(msg_may_trunc(false, IObuff), 0, false);
+  }
   msg_clr_eos();
-  ui_flush();
   msg_scrolled_ign = false;
 }
 
diff --git a/src/nvim/indent.c b/src/nvim/indent.c
index 806526b734..b10173135e 100644
--- a/src/nvim/indent.c
+++ b/src/nvim/indent.c
@@ -1004,19 +1004,20 @@ void op_reindent(oparg_T *oap, Indenter how)
       if (i > 1
           && (i % 50 == 0 || i == oap->line_count - 1)
           && oap->line_count > p_report) {
-        smsg(0, _("%" PRId64 " lines to indent... "), (int64_t)i);
+        snprintf(IObuff, IOSIZE, _("%" PRId64 " lines to indent... "), (int64_t)i);
+        // Restore cursor to avoid redrawing curwin in msg_show callback.
+        linenr_T save_lnum = curwin->w_cursor.lnum;
+        curwin->w_cursor.lnum = start_lnum;
+        msg_progress(IObuff, "indent", "running", 0, true, false);
+        curwin->w_cursor.lnum = save_lnum;
       }
 
       // Be vi-compatible: For lisp indenting the first line is not
       // indented, unless there is only one line.
-      if (i != oap->line_count - 1 || oap->line_count == 1
-          || how != get_lisp_indent) {
+      if (i != oap->line_count - 1 || oap->line_count == 1 || how != get_lisp_indent) {
         char *l = skipwhite(get_cursor_line_ptr());
-        if (*l == NUL) {                      // empty or blank line
-          amount = 0;
-        } else {
-          amount = how();                     // get the indent for this line
-        }
+        // Get indent for this line unless it is blank.
+        amount = *l == NUL ? 0 : how();
         if (amount >= 0 && set_indent(amount, 0)) {
           // did change the indent, call changed_lines() later
           if (first_changed == 0) {
@@ -1047,7 +1048,9 @@ void op_reindent(oparg_T *oap, Indenter how)
 
   if (oap->line_count > p_report) {
     i = oap->line_count - (i + 1);
-    smsg(0, NGETTEXT("%" PRId64 " line indented ", "%" PRId64 " lines indented ", i), (int64_t)i);
+    snprintf(IObuff, IOSIZE,
+             NGETTEXT("%" PRId64 " line indented ", "%" PRId64 " lines indented ", i), (int64_t)i);
+    msg_progress(IObuff, "indent", "success", 0, true, false);
   }
   if ((cmdmod.cmod_flags & CMOD_LOCKMARKS) == 0) {
     // set '[ and '] marks
diff --git a/src/nvim/insexpand.c b/src/nvim/insexpand.c
index 6e986eb5fe..964c2517d6 100644
--- a/src/nvim/insexpand.c
+++ b/src/nvim/insexpand.c
@@ -1944,11 +1944,8 @@ static void ins_compl_files(int count, char **files, bool thesaurus, int flags,
   for (int i = 0; i < count && !got_int && !ins_compl_interrupted(); i++) {
     FILE *fp = os_fopen(files[i], "r");  // open dictionary file
     if (flags != DICT_EXACT && !shortmess(SHM_COMPLETIONSCAN) && !compl_autocomplete) {
-      msg_hist_off = true;  // reset in msg_trunc()
-      msg_ext_set_kind("completion");
-      vim_snprintf(IObuff, IOSIZE,
-                   _("Scanning dictionary: %s"), files[i]);
-      msg_trunc(IObuff, true, HLF_R);
+      vim_snprintf(IObuff, IOSIZE, _("Scanning dictionary: %s"), files[i]);
+      msg_progress(IObuff, "completion", "running", HLF_R, false, true);
     }
 
     if (fp == NULL) {
@@ -3823,16 +3820,13 @@ static int process_next_cpt_value(ins_compl_next_state_T *st, int *compl_type_ar
       st->dict_f = DICT_EXACT;
     }
     if (!shortmess(SHM_COMPLETIONSCAN) && !compl_autocomplete) {
-      msg_hist_off = true;  // reset in msg_trunc()
-      msg_ext_overwrite = true;
-      msg_ext_set_kind("completion");
       vim_snprintf(IObuff, IOSIZE, _("Scanning: %s"),
                    st->ins_buf->b_fname == NULL
                    ? buf_spname(st->ins_buf)
                    : st->ins_buf->b_sfname == NULL
                    ? st->ins_buf->b_fname
                    : st->ins_buf->b_sfname);
-      msg_trunc(IObuff, true, HLF_R);
+      msg_progress(IObuff, "completion", "running", HLF_R, false, true);
     }
   } else if (*st->e_cpt == NUL) {
     status = INS_COMPL_CPT_END;
@@ -3865,11 +3859,8 @@ static int process_next_cpt_value(ins_compl_next_state_T *st, int *compl_type_ar
       } else if (*st->e_cpt == ']' || *st->e_cpt == 't') {
         compl_type = CTRL_X_TAGS;
         if (!shortmess(SHM_COMPLETIONSCAN) && !compl_autocomplete) {
-          msg_ext_set_kind("completion");
-          msg_hist_off = true;  // reset in msg_trunc()
-          msg_ext_overwrite = true;
           vim_snprintf(IObuff, IOSIZE, "%s", _("Scanning tags."));
-          msg_trunc(IObuff, true, HLF_R);
+          msg_progress(IObuff, "completion", "running", HLF_R, false, true);
         }
       }
     }
diff --git a/src/nvim/message.c b/src/nvim/message.c
index 4748bd1db9..1d7c24ce02 100644
--- a/src/nvim/message.c
+++ b/src/nvim/message.c
@@ -14,6 +14,7 @@
 #include "klib/kvec.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
+#include "nvim/api/vim.h"
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
 #include "nvim/buffer_defs.h"
@@ -387,7 +388,6 @@ MsgID msg_multihl(MsgID id, HlMessage hl_msg, const char *kind, bool history, bo
   msg_clr_eos();
   bool need_clear = false;
   bool hl_msg_updated = false;
-  msg_ext_history = history;
   if (kind != NULL) {
     msg_ext_set_kind(kind);
   }
@@ -1099,6 +1099,31 @@ char *msg_may_trunc(bool force, char *s)
   return s;
 }
 
+char *msg_progress(char *s, char *id, char *status, int hl_id, bool hist, bool trunc)
+{
+  Error err = ERROR_INIT;
+  Dict(echo_opts) opts = {
+    .kind = cstr_as_string("progress"),
+    .source = cstr_as_string("nvim"),
+    .status = cstr_as_string(status),
+    .id = CSTR_AS_OBJ(id),
+  };
+  if (hist && (!trunc || ui_has(kUIMessages))) {
+    msg_hist_add(s, -1, 0);
+  }
+  if (trunc) {
+    s = msg_may_trunc(false, s);
+  }
+  MAXSIZE_TEMP_ARRAY(chunk, 2);
+  MAXSIZE_TEMP_ARRAY(chunks, 1);
+  ADD_C(chunk, CSTR_AS_OBJ(s));
+  ADD_C(chunk, INTEGER_OBJ(hl_id));
+  ADD_C(chunks, ARRAY_OBJ(chunk));
+  nvim_echo(chunks, false, &opts, &err);
+  ui_flush();
+  return s;
+}
+
 void hl_msg_free(HlMessage hl_msg)
 {
   for (size_t i = 0; i < kv_size(hl_msg); i++) {