refactor: add const and remove unnecessary casts (#22841)

21 files changed, 71 insertions, 73 deletions

diff --git a/src/nvim/channel.c b/src/nvim/channel.c
index f68ee2b39e..a0fe3cc734 100644
--- a/src/nvim/channel.c
+++ b/src/nvim/channel.c
@@ -218,7 +218,7 @@ void channel_create_event(Channel *chan, const char *ext_source)
     source = ext_source;
   } else {
     eval_fmt_source_name_line(IObuff, sizeof(IObuff));
-    source = (const char *)IObuff;
+    source = IObuff;
   }
 
   assert(chan->id <= VARNUMBER_MAX);
diff --git a/src/nvim/charset.c b/src/nvim/charset.c
index a3aa6783ee..63459495f8 100644
--- a/src/nvim/charset.c
+++ b/src/nvim/charset.c
@@ -755,7 +755,7 @@ int ptr2cells(const char *p_in)
 /// @param s
 ///
 /// @return number of character cells.
-int vim_strsize(char *s)
+int vim_strsize(const char *s)
 {
   return vim_strnsize(s, MAXCOL);
 }
@@ -769,7 +769,7 @@ int vim_strsize(char *s)
 /// @param len
 ///
 /// @return Number of character cells.
-int vim_strnsize(char *s, int len)
+int vim_strnsize(const char *s, int len)
 {
   assert(s != NULL);
   int size = 0;
diff --git a/src/nvim/drawscreen.c b/src/nvim/drawscreen.c
index 1c8bf56e8e..13e9d1ea49 100644
--- a/src/nvim/drawscreen.c
+++ b/src/nvim/drawscreen.c
@@ -939,9 +939,9 @@ int showmode(void)
           }
           if (length - vim_strsize(edit_submode) > 0) {
             if (edit_submode_pre != NULL) {
-              msg_puts_attr((const char *)edit_submode_pre, attr);
+              msg_puts_attr(edit_submode_pre, attr);
             }
-            msg_puts_attr((const char *)edit_submode, attr);
+            msg_puts_attr(edit_submode, attr);
           }
           if (edit_submode_extra != NULL) {
             msg_puts_attr(" ", attr);  // Add a space in between.
@@ -950,7 +950,7 @@ int showmode(void)
             } else {
               sub_attr = attr;
             }
-            msg_puts_attr((const char *)edit_submode_extra, sub_attr);
+            msg_puts_attr(edit_submode_extra, sub_attr);
           }
         }
       } else {
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index fc9ddb75ef..edaa2bb809 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -596,7 +596,7 @@ int var_redir_start(char *name, int append)
 ///   :redir => foo
 ///   :let foo
 ///   :redir END
-void var_redir_str(char *value, int value_len)
+void var_redir_str(const char *value, int value_len)
 {
   if (redir_lval == NULL) {
     return;
@@ -2147,10 +2147,10 @@ int pattern_match(const char *pat, const char *text, bool ic)
   // avoid 'l' flag in 'cpoptions'
   char *save_cpo = p_cpo;
   p_cpo = empty_option;
-  regmatch.regprog = vim_regcomp((char *)pat, RE_MAGIC + RE_STRING);
+  regmatch.regprog = vim_regcomp(pat, RE_MAGIC + RE_STRING);
   if (regmatch.regprog != NULL) {
     regmatch.rm_ic = ic;
-    matches = vim_regexec_nl(&regmatch, (char *)text, (colnr_T)0);
+    matches = vim_regexec_nl(&regmatch, text, (colnr_T)0);
     vim_regfree(regmatch.regprog);
   }
   p_cpo = save_cpo;
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index df8004dc73..25d383d8ea 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -4670,7 +4670,7 @@ static void find_some_match(typval_T *const argvars, typval_T *const rettv,
     }
   }
 
-  regmatch.regprog = vim_regcomp((char *)pat, RE_MAGIC + RE_STRING);
+  regmatch.regprog = vim_regcomp(pat, RE_MAGIC + RE_STRING);
   if (regmatch.regprog != NULL) {
     regmatch.rm_ic = p_ic;
 
@@ -7895,7 +7895,7 @@ static void f_split(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
   }
 
   regmatch_T regmatch = {
-    .regprog = vim_regcomp((char *)pat, RE_MAGIC + RE_STRING),
+    .regprog = vim_regcomp(pat, RE_MAGIC + RE_STRING),
     .startp = { NULL },
     .endp = { NULL },
     .rm_ic = false,
@@ -7906,7 +7906,7 @@ static void f_split(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
       if (*str == NUL) {
         match = false;  // Empty item at the end.
       } else {
-        match = vim_regexec_nl(&regmatch, (char *)str, col);
+        match = vim_regexec_nl(&regmatch, str, col);
       }
       const char *end;
       if (match) {
diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index ac3c8c4f8e..621cb764f4 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -4742,7 +4742,7 @@ void ex_oldfiles(exarg_T *eap)
     }
     nr++;
     const char *fname = tv_get_string(TV_LIST_ITEM_TV(li));
-    if (!message_filtered((char *)fname)) {
+    if (!message_filtered(fname)) {
       msg_outnum(nr);
       msg_puts(": ");
       msg_outtrans((char *)tv_get_string(TV_LIST_ITEM_TV(li)));
diff --git a/src/nvim/ex_cmds2.c b/src/nvim/ex_cmds2.c
index c777efb445..a86676733f 100644
--- a/src/nvim/ex_cmds2.c
+++ b/src/nvim/ex_cmds2.c
@@ -201,7 +201,7 @@ void dialog_changed(buf_T *buf, bool checkall)
     .forceit = false,
   };
 
-  dialog_msg((char *)buff, _("Save changes to \"%s\"?"), buf->b_fname);
+  dialog_msg(buff, _("Save changes to \"%s\"?"), buf->b_fname);
   if (checkall) {
     ret = vim_dialog_yesnoallcancel(VIM_QUESTION, NULL, buff, 1);
   } else {
diff --git a/src/nvim/ex_session.c b/src/nvim/ex_session.c
index 855a5f7538..d47d40cbee 100644
--- a/src/nvim/ex_session.c
+++ b/src/nvim/ex_session.c
@@ -959,7 +959,7 @@ void ex_mkrc(exarg_T *eap)
 
   // When using 'viewdir' may have to create the directory.
   if (using_vdir && !os_isdir(p_vdir)) {
-    vim_mkdir_emsg((const char *)p_vdir, 0755);
+    vim_mkdir_emsg(p_vdir, 0755);
   }
 
   fd = open_exfile(fname, eap->forceit, WRITEBIN);
diff --git a/src/nvim/grid.c b/src/nvim/grid.c
index cd70e98047..3c4b1e9d70 100644
--- a/src/nvim/grid.c
+++ b/src/nvim/grid.c
@@ -197,10 +197,10 @@ void grid_put_schar(ScreenGrid *grid, int row, int col, char *schar, int attr)
 
 /// like grid_puts(), but output "text[len]".  When "len" is -1 output up to
 /// a NUL.
-int grid_puts_len(ScreenGrid *grid, char *text, int textlen, int row, int col, int attr)
+int grid_puts_len(ScreenGrid *grid, const char *text, int textlen, int row, int col, int attr)
 {
   size_t off;
-  char *ptr = text;
+  const char *ptr = text;
   int len = textlen;
   int c;
   size_t max_off;
diff --git a/src/nvim/highlight_group.c b/src/nvim/highlight_group.c
index 56fa206247..cce124de77 100644
--- a/src/nvim/highlight_group.c
+++ b/src/nvim/highlight_group.c
@@ -1631,7 +1631,7 @@ static bool highlight_list_arg(const int id, bool didh, const int type, int iarg
     }
   }
 
-  (void)syn_list_header(didh, vim_strsize((char *)ts) + (int)strlen(name) + 1, id, false);
+  (void)syn_list_header(didh, vim_strsize(ts) + (int)strlen(name) + 1, id, false);
   didh = true;
   if (!got_int) {
     if (*name != NUL) {
diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index dfbbfe9ab5..b5dd7a3e78 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -623,7 +623,7 @@ static bool nlua_init_packages(lua_State *lstate, bool is_standalone)
   lua_getglobal(lstate, "require");
   lua_pushstring(lstate, "vim._init_packages");
   if (nlua_pcall(lstate, 1, 0)) {
-    os_errmsg((char *)lua_tostring(lstate, -1));
+    os_errmsg(lua_tostring(lstate, -1));
     os_errmsg("\n");
     return false;
   }
diff --git a/src/nvim/lua/stdlib.c b/src/nvim/lua/stdlib.c
index ee5676e927..20a99b2836 100644
--- a/src/nvim/lua/stdlib.c
+++ b/src/nvim/lua/stdlib.c
@@ -288,7 +288,7 @@ int nlua_regex(lua_State *lstate)
   regprog_T *prog = NULL;
 
   TRY_WRAP(&err, {
-    prog = vim_regcomp((char *)text, RE_AUTO | RE_MAGIC | RE_STRICT);
+    prog = vim_regcomp(text, RE_AUTO | RE_MAGIC | RE_STRICT);
   });
 
   if (ERROR_SET(&err)) {
diff --git a/src/nvim/main.c b/src/nvim/main.c
index a16badc1a0..1f16ecff76 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -2153,7 +2153,7 @@ static void print_mainerr(const char *errstr, const char *str)
   os_errmsg(_(errstr));
   if (str != NULL) {
     os_errmsg(": \"");
-    os_errmsg((char *)str);
+    os_errmsg(str);
     os_errmsg("\"");
   }
   os_errmsg(_("\nMore info with \""));
diff --git a/src/nvim/match.c b/src/nvim/match.c
index 93c8a58051..29d4b7c225 100644
--- a/src/nvim/match.c
+++ b/src/nvim/match.c
@@ -98,7 +98,7 @@ static int match_add(win_T *wp, const char *const grp, const char *const pat, in
   if ((hlg_id = syn_check_group(grp, strlen(grp))) == 0) {
     return -1;
   }
-  if (pat != NULL && (regprog = vim_regcomp((char *)pat, RE_MAGIC)) == NULL) {
+  if (pat != NULL && (regprog = vim_regcomp(pat, RE_MAGIC)) == NULL) {
     semsg(_(e_invarg2), pat);
     return -1;
   }
@@ -1232,7 +1232,7 @@ void ex_match(exarg_T *eap)
     if (!eap->skip) {
       if (*end != NUL && !ends_excmd(*skipwhite(end + 1))) {
         xfree(g);
-        eap->errmsg = ex_errmsg(e_trailing_arg, (const char *)end);
+        eap->errmsg = ex_errmsg(e_trailing_arg, end);
         return;
       }
       if (*end != *p) {
@@ -1243,8 +1243,7 @@ void ex_match(exarg_T *eap)
 
       c = (uint8_t)(*end);
       *end = NUL;
-      match_add(curwin, (const char *)g, (const char *)p + 1, 10, id,
-                NULL, NULL);
+      match_add(curwin, g, p + 1, 10, id, NULL, NULL);
       xfree(g);
       *end = (char)c;
     }
diff --git a/src/nvim/message.c b/src/nvim/message.c
index aecb46c6bd..98ef6e5cba 100644
--- a/src/nvim/message.c
+++ b/src/nvim/message.c
@@ -216,13 +216,13 @@ void msg_grid_validate(void)
 /// When terminal not initialized (yet) os_errmsg(..) is used.
 ///
 /// @return  true if wait_return() not called
-int msg(char *s)
+int msg(const char *s)
 {
   return msg_attr_keep(s, 0, false, false);
 }
 
 /// Like msg() but keep it silent when 'verbosefile' is set.
-int verb_msg(char *s)
+int verb_msg(const char *s)
 {
   verbose_enter();
   int n = msg_attr_keep(s, 0, false, false);
@@ -278,8 +278,7 @@ void msg_multiattr(HlMessage hl_msg, const char *kind, bool history)
   msg_ext_set_kind(kind);
   for (uint32_t i = 0; i < kv_size(hl_msg); i++) {
     HlMessageChunk chunk = kv_A(hl_msg, i);
-    msg_multiline_attr((const char *)chunk.text.data, chunk.attr,
-                       true, &need_clear);
+    msg_multiline_attr(chunk.text.data, chunk.attr, true, &need_clear);
   }
   if (history && kv_size(hl_msg)) {
     add_msg_hist_multiattr(NULL, 0, 0, true, hl_msg);
@@ -305,7 +304,7 @@ bool msg_attr_keep(const char *s, int attr, bool keep, bool multiline)
 
   // Skip messages not match ":filter pattern".
   // Don't filter when there is an error.
-  if (!emsg_on_display && message_filtered((char *)s)) {
+  if (!emsg_on_display && message_filtered(s)) {
     return true;
   }
 
@@ -333,7 +332,7 @@ bool msg_attr_keep(const char *s, int attr, bool keep, bool multiline)
 
   // Truncate the message if needed.
   msg_start();
-  buf = msg_strtrunc((char *)s, false);
+  buf = msg_strtrunc(s, false);
   if (buf != NULL) {
     s = buf;
   }
@@ -349,8 +348,8 @@ bool msg_attr_keep(const char *s, int attr, bool keep, bool multiline)
   }
   retval = msg_end();
 
-  if (keep && retval && vim_strsize((char *)s) < (Rows - cmdline_row - 1) * Columns + sc_col) {
-    set_keep_msg((char *)s, 0);
+  if (keep && retval && vim_strsize(s) < (Rows - cmdline_row - 1) * Columns + sc_col) {
+    set_keep_msg(s, 0);
   }
 
   need_fileinfo = false;
@@ -365,7 +364,7 @@ bool msg_attr_keep(const char *s, int attr, bool keep, bool multiline)
 /// @return  an allocated string or NULL when no truncating is done.
 ///
 /// @param force  always truncate
-char *msg_strtrunc(char *s, int force)
+char *msg_strtrunc(const char *s, int force)
 {
   char *buf = NULL;
 
@@ -395,7 +394,7 @@ char *msg_strtrunc(char *s, int force)
 
 /// Truncate a string "s" to "buf" with cell width "room".
 /// "s" and "buf" may be equal.
-void trunc_string(char *s, char *buf, int room_in, int buflen)
+void trunc_string(const char *s, char *buf, int room_in, int buflen)
 {
   int room = room_in - 3;  // "..." takes 3 chars
   int half;
@@ -503,7 +502,7 @@ int smsg_attr(int attr, const char *s, ...)
   va_start(arglist, s);
   vim_vsnprintf(IObuff, IOSIZE, s, arglist);
   va_end(arglist);
-  return msg_attr((const char *)IObuff, attr);
+  return msg_attr(IObuff, attr);
 }
 
 int smsg_attr_keep(int attr, const char *s, ...)
@@ -514,7 +513,7 @@ int smsg_attr_keep(int attr, const char *s, ...)
   va_start(arglist, s);
   vim_vsnprintf(IObuff, IOSIZE, s, arglist);
   va_end(arglist);
-  return msg_attr_keep((const char *)IObuff, attr, true, false);
+  return msg_attr_keep(IObuff, attr, true, false);
 }
 
 // Remember the last sourcing name/lnum used in an error message, so that it
@@ -862,7 +861,7 @@ void siemsg(const char *s, ...)
 }
 
 /// Give an "Internal error" message.
-void internal_error(char *where)
+void internal_error(const char *where)
 {
   siemsg(_(e_intern2), where);
 }
@@ -1327,7 +1326,7 @@ static void hit_return_msg(void)
 }
 
 /// Set "keep_msg" to "s".  Free the old value and check for NULL pointer.
-void set_keep_msg(char *s, int attr)
+void set_keep_msg(const char *s, int attr)
 {
   xfree(keep_msg);
   if (s != NULL && msg_silent == 0) {
@@ -1562,7 +1561,7 @@ int msg_outtrans_len_attr(const char *msgstr, int len, int attr)
 
   // If the string starts with a composing character first draw a space on
   // which the composing char can be drawn.
-  if (utf_iscomposing(utf_ptr2char((char *)msgstr))) {
+  if (utf_iscomposing(utf_ptr2char(msgstr))) {
     msg_puts_attr(" ", attr);
   }
 
@@ -1598,7 +1597,7 @@ int msg_outtrans_len_attr(const char *msgstr, int len, int attr)
           msg_puts_attr_len(plain_start, str - plain_start, attr);
         }
         plain_start = str + 1;
-        msg_puts_attr((const char *)s, attr == 0 ? HL_ATTR(HLF_8) : attr);
+        msg_puts_attr(s, attr == 0 ? HL_ATTR(HLF_8) : attr);
         retval += (int)strlen(s);
       } else {
         retval++;
@@ -1674,7 +1673,7 @@ int msg_outtrans_special(const char *strstart, bool from, int maxlen)
       // single-byte character or illegal byte
       text = (char *)transchar_byte_buf(NULL, (uint8_t)text[0]);
     }
-    const int len = vim_strsize((char *)text);
+    const int len = vim_strsize(text);
     if (maxlen > 0 && retval + len >= maxlen) {
       break;
     }
@@ -1966,7 +1965,7 @@ void msg_prt_line(char *s, int list)
 /// Use grid_puts() to output one multi-byte character.
 ///
 /// @return  the pointer "s" advanced to the next character.
-static char *screen_puts_mbyte(char *s, int l, int attr)
+static const char *screen_puts_mbyte(const char *s, int l, int attr)
 {
   int cw;
   attr = hl_combine_attr(HL_ATTR(HLF_MSG), attr);
@@ -2212,7 +2211,7 @@ static void msg_puts_display(const char *str, int maxlen, int attr, int recurse)
         } else {
           l = utfc_ptr2len(s);
         }
-        s = screen_puts_mbyte((char *)s, l, attr);
+        s = screen_puts_mbyte(s, l, attr);
         did_last_char = true;
       } else {
         did_last_char = false;
@@ -2229,7 +2228,7 @@ static void msg_puts_display(const char *str, int maxlen, int attr, int recurse)
 
       if (p_more) {
         // Store text for scrolling back.
-        store_sb_text((char **)&sb_str, (char *)s, attr, &sb_col, true);
+        store_sb_text(&sb_str, s, attr, &sb_col, true);
       }
 
       inc_msg_scrolled();
@@ -2274,7 +2273,7 @@ static void msg_puts_display(const char *str, int maxlen, int attr, int recurse)
 
     if (wrap && p_more && !recurse) {
       // Store text for scrolling back.
-      store_sb_text((char **)&sb_str, (char *)s, attr, &sb_col, true);
+      store_sb_text(&sb_str, s, attr, &sb_col, true);
     }
 
     if (*s == '\n') {               // go to next line
@@ -2312,7 +2311,7 @@ static void msg_puts_display(const char *str, int maxlen, int attr, int recurse)
       // characters and draw them all at once later.
       if (cmdmsg_rl || (cw > 1 && msg_col + t_col >= Columns - 1)) {
         if (l > 1) {
-          s = screen_puts_mbyte((char *)s, l, attr) - 1;
+          s = screen_puts_mbyte(s, l, attr) - 1;
         } else {
           msg_screen_putchar(*s, attr);
         }
@@ -2333,7 +2332,7 @@ static void msg_puts_display(const char *str, int maxlen, int attr, int recurse)
     t_puts(&t_col, t_s, s, attr);
   }
   if (p_more && !recurse && !(s == sb_str + 1 && *sb_str == '\n')) {
-    store_sb_text((char **)&sb_str, (char *)s, attr, &sb_col, false);
+    store_sb_text(&sb_str, s, attr, &sb_col, false);
   }
 
   msg_check();
@@ -2341,7 +2340,7 @@ static void msg_puts_display(const char *str, int maxlen, int attr, int recurse)
 
 /// @return  true when ":filter pattern" was used and "msg" does not match
 ///          "pattern".
-bool message_filtered(char *msg)
+bool message_filtered(const char *msg)
 {
   if (cmdmod.cmod_filter_regmatch.regprog == NULL) {
     return false;
@@ -2507,7 +2506,7 @@ static sb_clear_T do_clear_sb_text = SB_CLEAR_NONE;
 /// @param sb_str  start of string
 /// @param s  just after string
 /// @param finish  line ends
-static void store_sb_text(char **sb_str, char *s, int attr, int *sb_col, int finish)
+static void store_sb_text(const char **sb_str, const char *s, int attr, int *sb_col, int finish)
 {
   msgchunk_T *mp;
 
@@ -2681,7 +2680,7 @@ static void t_puts(int *t_col, const char *t_s, const char *s, int attr)
   attr = hl_combine_attr(HL_ATTR(HLF_MSG), attr);
   // Output postponed text.
   msg_didout = true;  // Remember that line is not empty.
-  grid_puts_len(&msg_grid_adj, (char *)t_s, (int)(s - t_s), msg_row, msg_col, attr);
+  grid_puts_len(&msg_grid_adj, t_s, (int)(s - t_s), msg_row, msg_col, attr);
   msg_col += *t_col;
   *t_col = 0;
   // If the string starts with a composing character don't increment the
@@ -3308,7 +3307,7 @@ static void redir_write(const char *const str, const ptrdiff_t maxlen)
       write_reg_contents(redir_reg, s, (ssize_t)len, true);
     }
     if (redir_vname) {
-      var_redir_str((char *)s, (int)maxlen);
+      var_redir_str(s, (int)maxlen);
     }
 
     // Write and adjust the current column.
@@ -3417,7 +3416,7 @@ int verbose_open(void)
 
 /// Give a warning message (for searching).
 /// Use 'w' highlighting and may repeat the message after redrawing
-void give_warning(char *message, bool hl)
+void give_warning(const char *message, bool hl)
   FUNC_ATTR_NONNULL_ARG(1)
 {
   // Don't do this for ":silent".
@@ -3440,7 +3439,7 @@ void give_warning(char *message, bool hl)
     msg_ext_set_kind("wmsg");
   }
 
-  if (msg_attr((const char *)message, keep_msg_attr) && msg_scrolled == 0) {
+  if (msg_attr(message, keep_msg_attr) && msg_scrolled == 0) {
     set_keep_msg(message, keep_msg_attr);
   }
   msg_didout = false;  // Overwrite this message.
@@ -3450,7 +3449,7 @@ void give_warning(char *message, bool hl)
   no_wait_return--;
 }
 
-void give_warning2(char *const message, char *const a1, bool hl)
+void give_warning2(const char *const message, const char *const a1, bool hl)
 {
   vim_snprintf(IObuff, IOSIZE, message, a1);
   give_warning(IObuff, hl);
diff --git a/src/nvim/os/env.c b/src/nvim/os/env.c
index 30092b9142..5b8c060e7a 100644
--- a/src/nvim/os/env.c
+++ b/src/nvim/os/env.c
@@ -494,7 +494,7 @@ void init_homedir(void)
     // links.  Don't do it when we can't return.
     if (os_dirname(os_buf, MAXPATHL) == OK && os_chdir(os_buf) == 0) {
       if (!os_chdir(var) && os_dirname(IObuff, IOSIZE) == OK) {
-        var = (char *)IObuff;
+        var = IObuff;
       }
       if (os_chdir(os_buf) != 0) {
         emsg(_(e_prev_dir));
diff --git a/src/nvim/regexp.c b/src/nvim/regexp.c
index 122f3e2020..0b9a9bbdec 100644
--- a/src/nvim/regexp.c
+++ b/src/nvim/regexp.c
@@ -2304,10 +2304,10 @@ static uint8_t regname[][30] = {
 // Returns the program in allocated memory.
 // Use vim_regfree() to free the memory.
 // Returns NULL for an error.
-regprog_T *vim_regcomp(char *expr_arg, int re_flags)
+regprog_T *vim_regcomp(const char *expr_arg, int re_flags)
 {
   regprog_T *prog = NULL;
-  char *expr = expr_arg;
+  const char *expr = expr_arg;
 
   regexp_engine = (int)p_re;
 
@@ -2403,7 +2403,7 @@ void free_regexp_stuff(void)
 
 #endif
 
-static void report_re_switch(char *pat)
+static void report_re_switch(const char *pat)
 {
   if (p_verbose > 0) {
     verbose_enter();
@@ -2425,7 +2425,7 @@ static void report_re_switch(char *pat)
 /// @param nl
 ///
 /// @return true if there is a match, false if not.
-static bool vim_regexec_string(regmatch_T *rmp, char *line, colnr_T col, bool nl)
+static bool vim_regexec_string(regmatch_T *rmp, const char *line, colnr_T col, bool nl)
 {
   regexec_T rex_save;
   bool rex_in_use_save = rex_in_use;
@@ -2482,7 +2482,7 @@ static bool vim_regexec_string(regmatch_T *rmp, char *line, colnr_T col, bool nl
 
 // Note: "*prog" may be freed and changed.
 // Return true if there is a match, false if not.
-bool vim_regexec_prog(regprog_T **prog, bool ignore_case, char *line, colnr_T col)
+bool vim_regexec_prog(regprog_T **prog, bool ignore_case, const char *line, colnr_T col)
 {
   regmatch_T regmatch = { .regprog = *prog, .rm_ic = ignore_case };
   bool r = vim_regexec_string(&regmatch, line, col, false);
@@ -2492,7 +2492,7 @@ bool vim_regexec_prog(regprog_T **prog, bool ignore_case, char *line, colnr_T co
 
 // Note: "rmp->regprog" may be freed and changed.
 // Return true if there is a match, false if not.
-bool vim_regexec(regmatch_T *rmp, char *line, colnr_T col)
+bool vim_regexec(regmatch_T *rmp, const char *line, colnr_T col)
 {
   return vim_regexec_string(rmp, line, col, false);
 }
@@ -2500,7 +2500,7 @@ bool vim_regexec(regmatch_T *rmp, char *line, colnr_T col)
 // Like vim_regexec(), but consider a "\n" in "line" to be a line break.
 // Note: "rmp->regprog" may be freed and changed.
 // Return true if there is a match, false if not.
-bool vim_regexec_nl(regmatch_T *rmp, char *line, colnr_T col)
+bool vim_regexec_nl(regmatch_T *rmp, const char *line, colnr_T col)
 {
   return vim_regexec_string(rmp, line, col, true);
 }
diff --git a/src/nvim/search.c b/src/nvim/search.c
index 67b6f5e6a6..525cec8b02 100644
--- a/src/nvim/search.c
+++ b/src/nvim/search.c
@@ -4159,10 +4159,10 @@ static void show_pat_in_path(char *line, int type, bool did_show, int action, FI
     }
     if (action == ACTION_SHOW_ALL) {
       snprintf(IObuff, IOSIZE, "%3ld: ", count);  // Show match nr.
-      msg_puts((const char *)IObuff);
+      msg_puts(IObuff);
       snprintf(IObuff, IOSIZE, "%4" PRIdLINENR, *lnum);  // Show line nr.
       // Highlight line numbers.
-      msg_puts_attr((const char *)IObuff, HL_ATTR(HLF_N));
+      msg_puts_attr(IObuff, HL_ATTR(HLF_N));
       msg_puts(" ");
     }
     msg_prt_line(line, false);
diff --git a/src/nvim/spellfile.c b/src/nvim/spellfile.c
index 8927b599d0..c68eee3526 100644
--- a/src/nvim/spellfile.c
+++ b/src/nvim/spellfile.c
@@ -608,7 +608,7 @@ slang_T *spell_load_file(char *fname, char *lang, slang_T *old_lp, bool silent)
       semsg(_(e_notopen), fname);
     } else if (p_verbose > 2) {
       verbose_enter();
-      smsg((char *)e_notopen, fname);
+      smsg(e_notopen, fname);
       verbose_leave();
     }
     goto endFAIL;
@@ -4047,7 +4047,7 @@ static int tree_add_word(spellinfo_T *spin, const char_u *word, wordnode_T *root
     node = *prev;
   }
 #ifdef SPELL_PRINTTREE
-  smsg((char_u *)"Added \"%s\"", word);
+  smsg("Added \"%s\"", word);
   spell_print_tree(root->wn_sibling);
 #endif
 
diff --git a/src/nvim/spellsuggest.c b/src/nvim/spellsuggest.c
index 705e215dfa..d28460a63d 100644
--- a/src/nvim/spellsuggest.c
+++ b/src/nvim/spellsuggest.c
@@ -551,7 +551,7 @@ void spell_suggest(int count)
       vim_snprintf(IObuff, IOSIZE, ":ot \"%.*s\" egnahC",
                    sug.su_badlen, sug.su_badptr);
     }
-    msg_puts((const char *)IObuff);
+    msg_puts(IObuff);
     msg_clr_eos();
     msg_putchar('\n');
 
@@ -570,16 +570,16 @@ void spell_suggest(int count)
       if (cmdmsg_rl) {
         rl_mirror_ascii(IObuff);
       }
-      msg_puts((const char *)IObuff);
+      msg_puts(IObuff);
 
       vim_snprintf(IObuff, IOSIZE, " \"%s\"", wcopy);
-      msg_puts((const char *)IObuff);
+      msg_puts(IObuff);
 
       // The word may replace more than "su_badlen".
       if (sug.su_badlen < stp->st_orglen) {
         vim_snprintf(IObuff, IOSIZE, _(" < \"%.*s\""),
                      stp->st_orglen, sug.su_badptr);
-        msg_puts((const char *)IObuff);
+        msg_puts(IObuff);
       }
 
       if (p_verbose > 0) {
@@ -597,7 +597,7 @@ void spell_suggest(int count)
           rl_mirror_ascii(IObuff + 1);
         }
         msg_advance(30);
-        msg_puts((const char *)IObuff);
+        msg_puts(IObuff);
       }
       msg_putchar('\n');
     }
diff --git a/src/nvim/tag.c b/src/nvim/tag.c
index 852e7e6e7c..2d9d0de951 100644
--- a/src/nvim/tag.c
+++ b/src/nvim/tag.c
@@ -726,7 +726,7 @@ void do_tag(char *tag, int type, int count, int forceit, int verbose)
         if ((num_matches > prev_num_matches || new_tag)
             && num_matches > 1) {
           if (ic) {
-            msg_attr((const char *)IObuff, HL_ATTR(HLF_W));
+            msg_attr(IObuff, HL_ATTR(HLF_W));
           } else {
             msg(IObuff);
           }