refactor: replace char_u #18429

Work on https://github.com/neovim/neovim/issues/459

55 files changed, 519 insertions, 559 deletions

diff --git a/src/nvim/api/command.c b/src/nvim/api/command.c
index 2b2fb446a0..80a5449d29 100644
--- a/src/nvim/api/command.c
+++ b/src/nvim/api/command.c
@@ -413,7 +413,7 @@ String nvim_cmd(uint64_t channel_id, Dict(cmd) *cmd, Dict(cmd_opts) *opts, Error
 
   // Simply pass the first argument (if it exists) as the arg pointer to `set_cmd_addr_type()`
   // since it only ever checks the first argument.
-  set_cmd_addr_type(&ea, argc > 0 ? (char_u *)args[0] : NULL);
+  set_cmd_addr_type(&ea, argc > 0 ? args[0] : NULL);
 
   if (HAS_KEY(cmd->range)) {
     if (!(ea.argt & EX_RANGE)) {
diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index c5881dbc5f..bf3fb04a18 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -2109,7 +2109,7 @@ Dictionary nvim_eval_statusline(String str, Dict(eval_statusline) *opts, Error *
   bool highlights = false;
 
   if (str.size < 2 || memcmp(str.data, "%!", 2)) {
-    const char *const errmsg = check_stl_option((char_u *)str.data);
+    const char *const errmsg = check_stl_option(str.data);
     if (errmsg) {
       api_set_error(err, kErrorTypeValidation, "%s", errmsg);
       return result;
diff --git a/src/nvim/autocmd.c b/src/nvim/autocmd.c
index 69f01afcb6..7301e07a06 100644
--- a/src/nvim/autocmd.c
+++ b/src/nvim/autocmd.c
@@ -174,7 +174,7 @@ static void aupat_show(AutoPat *ap, event_T event, int previous_group)
   }
 
   msg_col = 4;
-  msg_outtrans((char_u *)ap->pat);
+  msg_outtrans(ap->pat);
 
   for (AutoCmd *ac = ap->cmds; ac != NULL; ac = ac->next) {
     // skip removed commands
@@ -195,10 +195,10 @@ static void aupat_show(AutoPat *ap, event_T event, int previous_group)
       size_t msglen = 100;
       char *msg = (char *)xmallocz(msglen);
       snprintf(msg, msglen, "%s [%s]", exec_to_string, ac->desc);
-      msg_outtrans((char_u *)msg);
+      msg_outtrans(msg);
       XFREE_CLEAR(msg);
     } else {
-      msg_outtrans((char_u *)exec_to_string);
+      msg_outtrans(exec_to_string);
     }
     XFREE_CLEAR(exec_to_string);
     if (p_verbose > 0) {
@@ -471,7 +471,7 @@ void augroup_del(char *name, bool stupid_legacy_mode)
       FOR_ALL_AUEVENTS(event) {
         FOR_ALL_AUPATS_IN_EVENT(event, ap) {
           if (ap->group == i && ap->pat != NULL) {
-            give_warning((char_u *)_("W19: Deleting augroup that is still in use"), true);
+            give_warning(_("W19: Deleting augroup that is still in use"), true);
             map_put(String, int)(&map_augroup_name_to_id, cstr_as_string(name), AUGROUP_DELETED);
             augroup_map_del(ap->group, NULL);
             return;
@@ -717,7 +717,7 @@ char *au_event_disable(char *what)
   } else {
     STRCAT(new_ei, what);
   }
-  set_string_option_direct("ei", -1, (char_u *)new_ei, OPT_FREE, SID_NONE);
+  set_string_option_direct("ei", -1, new_ei, OPT_FREE, SID_NONE);
   xfree(new_ei);
 
   return save_ei;
@@ -726,7 +726,7 @@ char *au_event_disable(char *what)
 void au_event_restore(char *old_ei)
 {
   if (old_ei != NULL) {
-    set_string_option_direct("ei", -1, (char_u *)old_ei, OPT_FREE, SID_NONE);
+    set_string_option_direct("ei", -1, old_ei, OPT_FREE, SID_NONE);
     xfree(old_ei);
   }
 }
diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index 85e34e910d..46adb55746 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -948,7 +948,7 @@ char *do_bufdel(int command, char_u *arg, int addr_count, int start_bnr, int end
   int deleted = 0;                // number of buffers deleted
   char *errormsg = NULL;   // return value
   int bnr;                        // buffer number
-  char_u *p;
+  char *p;
 
   if (addr_count == 0) {
     (void)do_buffer(command, DOBUF_CURRENT, FORWARD, 0, forceit);
@@ -985,13 +985,12 @@ char *do_bufdel(int command, char_u *arg, int addr_count, int start_bnr, int end
           break;
         }
         if (!ascii_isdigit(*arg)) {
-          p = skiptowhite_esc(arg);
-          bnr = buflist_findpat(arg, p, command == DOBUF_WIPE,
-                                false, false);
+          p = (char *)skiptowhite_esc(arg);
+          bnr = buflist_findpat(arg, (char_u *)p, command == DOBUF_WIPE, false, false);
           if (bnr < 0) {                    // failed
             break;
           }
-          arg = p;
+          arg = (char_u *)p;
         } else {
           bnr = getdigits_int(&arg, false, 0);
         }
@@ -1679,8 +1678,8 @@ static inline void buf_init_changedtick(buf_T *const buf)
 /// @return  pointer to the buffer
 buf_T *buflist_new(char_u *ffname_arg, char_u *sfname_arg, linenr_T lnum, int flags)
 {
-  char_u *ffname = ffname_arg;
-  char_u *sfname = sfname_arg;
+  char *ffname = (char *)ffname_arg;
+  char *sfname = (char *)sfname_arg;
   buf_T *buf;
 
   fname_expand(curbuf, &ffname, &sfname);       // will allocate ffname
@@ -1690,11 +1689,9 @@ buf_T *buflist_new(char_u *ffname_arg, char_u *sfname_arg, linenr_T lnum, int fl
   // We can use inode numbers when the file exists.  Works better
   // for hard links.
   FileID file_id;
-  bool file_id_valid = (sfname != NULL
-                        && os_fileid((char *)sfname, &file_id));
+  bool file_id_valid = (sfname != NULL && os_fileid(sfname, &file_id));
   if (ffname != NULL && !(flags & (BLN_DUMMY | BLN_NEW))
-      && (buf = buflist_findname_file_id(ffname, &file_id,
-                                         file_id_valid)) != NULL) {
+      && (buf = buflist_findname_file_id(ffname, &file_id, file_id_valid)) != NULL) {
     xfree(ffname);
     if (lnum != 0) {
       buflist_setfpos(buf, (flags & BLN_NOCURWIN) ? NULL : curwin,
@@ -1749,8 +1746,8 @@ buf_T *buflist_new(char_u *ffname_arg, char_u *sfname_arg, linenr_T lnum, int fl
   }
 
   if (ffname != NULL) {
-    buf->b_ffname = ffname;
-    buf->b_sfname = vim_strsave(sfname);
+    buf->b_ffname = (char_u *)ffname;
+    buf->b_sfname = vim_strsave((char_u *)sfname);
   }
 
   clear_wininfo(buf);
@@ -2045,20 +2042,20 @@ void buflist_getfpos(void)
 /// @return  buffer or NULL if not found
 buf_T *buflist_findname_exp(char_u *fname)
 {
-  char_u *ffname;
+  char *ffname;
   buf_T *buf = NULL;
 
   // First make the name into a full path name
-  ffname = (char_u *)FullName_save((char *)fname,
+  ffname = FullName_save((char *)fname,
 #ifdef UNIX
-                                   // force expansion, get rid of symbolic links
-                                   true
+                         // force expansion, get rid of symbolic links
+                         true
 #else
-                                   false
+                         false
 #endif
-                                   );  // NOLINT(whitespace/parens)
+                         );  // NOLINT(whitespace/parens)
   if (ffname != NULL) {
-    buf = buflist_findname(ffname);
+    buf = buflist_findname((char_u *)ffname);
     xfree(ffname);
   }
   return buf;
@@ -2073,14 +2070,14 @@ buf_T *buflist_findname(char_u *ffname)
 {
   FileID file_id;
   bool file_id_valid = os_fileid((char *)ffname, &file_id);
-  return buflist_findname_file_id(ffname, &file_id, file_id_valid);
+  return buflist_findname_file_id((char *)ffname, &file_id, file_id_valid);
 }
 
 /// Same as buflist_findname(), but pass the FileID structure to avoid
 /// getting it twice for the same file.
 ///
 /// @return  buffer or NULL if not found
-static buf_T *buflist_findname_file_id(char_u *ffname, FileID *file_id, bool file_id_valid)
+static buf_T *buflist_findname_file_id(char *ffname, FileID *file_id, bool file_id_valid)
   FUNC_ATTR_PURE
 {
   // Start at the last buffer, expect to find a match sooner.
@@ -2213,7 +2210,7 @@ int buflist_findpat(const char_u *pattern, const char_u *pattern_end, bool unlis
 
 typedef struct {
   buf_T *buf;
-  char_u *match;
+  char *match;
 } bufmatch_T;
 
 /// Compare functions for qsort() below, that compares b_last_used.
@@ -2236,9 +2233,9 @@ int ExpandBufnames(char_u *pat, int *num_file, char_u ***file, int options)
 {
   int count = 0;
   int round;
-  char_u *p;
+  char *p;
   int attempt;
-  char_u *patc;
+  char *patc;
   bufmatch_T *matches = NULL;
 
   *num_file = 0;                    // return values in case of FAIL
@@ -2254,20 +2251,20 @@ int ExpandBufnames(char_u *pat, int *num_file, char_u ***file, int options)
     STRCPY(patc, "\\(^\\|[\\/]\\)");
     STRCPY(patc + 11, pat + 1);
   } else {
-    patc = pat;
+    patc = (char *)pat;
   }
 
   // attempt == 0: try match with    '\<', match at start of word
   // attempt == 1: try match without '\<', match anywhere
   for (attempt = 0; attempt <= 1; attempt++) {
-    if (attempt > 0 && patc == pat) {
+    if (attempt > 0 && (char_u *)patc == pat) {
       break;            // there was no anchor, no need to try again
     }
 
     regmatch_T regmatch;
-    regmatch.regprog = vim_regcomp((char *)patc + attempt * 11, RE_MAGIC);
+    regmatch.regprog = vim_regcomp(patc + attempt * 11, RE_MAGIC);
     if (regmatch.regprog == NULL) {
-      if (patc != pat) {
+      if ((char_u *)patc != pat) {
         xfree(patc);
       }
       return FAIL;
@@ -2294,16 +2291,16 @@ int ExpandBufnames(char_u *pat, int *num_file, char_u ***file, int options)
             count++;
           } else {
             if (options & WILD_HOME_REPLACE) {
-              p = home_replace_save(buf, p);
+              p = (char *)home_replace_save(buf, (char_u *)p);
             } else {
-              p = vim_strsave(p);
+              p = xstrdup(p);
             }
             if (matches != NULL) {
               matches[count].buf = buf;
               matches[count].match = p;
               count++;
             } else {
-              (*file)[count++] = p;
+              (*file)[count++] = (char_u *)p;
             }
           }
         }
@@ -2325,7 +2322,7 @@ int ExpandBufnames(char_u *pat, int *num_file, char_u ***file, int options)
     }
   }
 
-  if (patc != pat) {
+  if ((char_u *)patc != pat) {
     xfree(patc);
   }
 
@@ -2337,12 +2334,12 @@ int ExpandBufnames(char_u *pat, int *num_file, char_u ***file, int options)
     // if the current buffer is first in the list, place it at the end
     if (matches[0].buf == curbuf) {
       for (int i = 1; i < count; i++) {
-        (*file)[i - 1] = matches[i].match;
+        (*file)[i - 1] = (char_u *)matches[i].match;
       }
-      (*file)[count - 1] = matches[0].match;
+      (*file)[count - 1] = (char_u *)matches[0].match;
     } else {
       for (int i = 0; i < count; i++) {
-        (*file)[i] = matches[i].match;
+        (*file)[i] = (char_u *)matches[i].match;
       }
     }
     xfree(matches);
@@ -2355,12 +2352,12 @@ int ExpandBufnames(char_u *pat, int *num_file, char_u ***file, int options)
 /// Check for a match on the file name for buffer "buf" with regprog "prog".
 ///
 /// @param ignore_case  When true, ignore case. Use 'fic' otherwise.
-static char_u *buflist_match(regmatch_T *rmp, buf_T *buf, bool ignore_case)
+static char *buflist_match(regmatch_T *rmp, buf_T *buf, bool ignore_case)
 {
   // First try the short file name, then the long file name.
-  char_u *match = fname_match(rmp, buf->b_sfname, ignore_case);
+  char *match = fname_match(rmp, (char *)buf->b_sfname, ignore_case);
   if (match == NULL && rmp->regprog != NULL) {
-    match = fname_match(rmp, buf->b_ffname, ignore_case);
+    match = fname_match(rmp, (char *)buf->b_ffname, ignore_case);
   }
   return match;
 }
@@ -2370,20 +2367,20 @@ static char_u *buflist_match(regmatch_T *rmp, buf_T *buf, bool ignore_case)
 /// @param ignore_case  When true, ignore case. Use 'fileignorecase' otherwise.
 ///
 /// @return  "name" when there is a match, NULL when not.
-static char_u *fname_match(regmatch_T *rmp, char_u *name, bool ignore_case)
+static char *fname_match(regmatch_T *rmp, char *name, bool ignore_case)
 {
-  char_u *match = NULL;
-  char_u *p;
+  char *match = NULL;
+  char *p;
 
   if (name != NULL) {
     // Ignore case when 'fileignorecase' or the argument is set.
     rmp->rm_ic = p_fic || ignore_case;
-    if (vim_regexec(rmp, name, (colnr_T)0)) {
+    if (vim_regexec(rmp, (char_u *)name, (colnr_T)0)) {
       match = name;
     } else if (rmp->regprog != NULL) {
       // Replace $(HOME) with '~' and try matching again.
-      p = home_replace_save(NULL, name);
-      if (vim_regexec(rmp, p, (colnr_T)0)) {
+      p = (char *)home_replace_save(NULL, (char_u *)name);
+      if (vim_regexec(rmp, (char_u *)p, (colnr_T)0)) {
         match = name;
       }
       xfree(p);
@@ -2658,7 +2655,7 @@ void buflist_list(exarg_T *eap)
     if (buf_spname(buf) != NULL) {
       STRLCPY(NameBuff, buf_spname(buf), MAXPATHL);
     } else {
-      home_replace(buf, (char_u *)buf->b_fname, NameBuff, MAXPATHL, true);
+      home_replace(buf, buf->b_fname, (char *)NameBuff, MAXPATHL, true);
     }
 
     if (message_filtered(NameBuff)) {
@@ -2688,7 +2685,7 @@ void buflist_list(exarg_T *eap)
     }
 
     // put "line 999" in column 40 or after the file name
-    i = 40 - vim_strsize(IObuff);
+    i = 40 - vim_strsize((char *)IObuff);
     do {
       IObuff[len++] = ' ';
     } while (--i > 0 && len < IOSIZE - 18);
@@ -2699,7 +2696,7 @@ void buflist_list(exarg_T *eap)
                    buf == curbuf ? (int64_t)curwin->w_cursor.lnum : (int64_t)buflist_findlnum(buf));
     }
 
-    msg_outtrans(IObuff);
+    msg_outtrans((char *)IObuff);
     line_breakcheck();
   }
 
@@ -2735,10 +2732,10 @@ int buflist_name_nr(int fnum, char_u **fname, linenr_T *lnum)
 /// @param message  give message when buffer already exists
 ///
 /// @return  FAIL for failure (file name already in use by other buffer) OK otherwise.
-int setfname(buf_T *buf, char_u *ffname_arg, char_u *sfname_arg, bool message)
+int setfname(buf_T *buf, char *ffname_arg, char *sfname_arg, bool message)
 {
-  char_u *ffname = ffname_arg;
-  char_u *sfname = sfname_arg;
+  char *ffname = ffname_arg;
+  char *sfname = sfname_arg;
   buf_T *obuf = NULL;
   FileID file_id;
   bool file_id_valid = false;
@@ -2760,7 +2757,7 @@ int setfname(buf_T *buf, char_u *ffname_arg, char_u *sfname_arg, bool message)
     // If the file name is already used in another buffer:
     // - if the buffer is loaded, fail
     // - if the buffer is not loaded, delete it from the list
-    file_id_valid = os_fileid((char *)ffname, &file_id);
+    file_id_valid = os_fileid(ffname, &file_id);
     if (!(buf->b_flags & BF_DUMMY)) {
       obuf = buflist_findname_file_id(ffname, &file_id, file_id_valid);
     }
@@ -2775,16 +2772,16 @@ int setfname(buf_T *buf, char_u *ffname_arg, char_u *sfname_arg, bool message)
       // delete from the list
       close_buffer(NULL, obuf, DOBUF_WIPE, false, false);
     }
-    sfname = vim_strsave(sfname);
+    sfname = xstrdup(sfname);
 #ifdef USE_FNAME_CASE
-    path_fix_case(sfname);            // set correct case for short file name
+    path_fix_case((char_u *)sfname);            // set correct case for short file name
 #endif
     if (buf->b_sfname != buf->b_ffname) {
       xfree(buf->b_sfname);
     }
     xfree(buf->b_ffname);
-    buf->b_ffname = ffname;
-    buf->b_sfname = sfname;
+    buf->b_ffname = (char_u *)ffname;
+    buf->b_sfname = (char_u *)sfname;
   }
   buf->b_fname = (char *)buf->b_sfname;
   if (!file_id_valid) {
@@ -2814,7 +2811,7 @@ void buf_set_name(int fnum, char_u *name)
     buf->b_sfname = NULL;
     // Allocate ffname and expand into full path.  Also resolves .lnk
     // files on Win32.
-    fname_expand(buf, &buf->b_ffname, &buf->b_sfname);
+    fname_expand(buf, (char **)&buf->b_ffname, (char **)&buf->b_sfname);
     buf->b_fname = (char *)buf->b_sfname;
   }
 }
@@ -2859,16 +2856,16 @@ buf_T *setaltfname(char_u *ffname, char_u *sfname, linenr_T lnum)
 /// @param errmsg  give error message
 char_u *getaltfname(bool errmsg)
 {
-  char_u *fname;
+  char *fname;
   linenr_T dummy;
 
-  if (buflist_name_nr(0, &fname, &dummy) == FAIL) {
+  if (buflist_name_nr(0, (char_u **)&fname, &dummy) == FAIL) {
     if (errmsg) {
       emsg(_(e_noalt));
     }
     return NULL;
   }
-  return fname;
+  return (char_u *)fname;
 }
 
 /// Add a file name to the buflist and return its number.
@@ -2916,7 +2913,7 @@ void buflist_altfpos(win_T *win)
 bool otherfile(char_u *ffname)
   FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ALL
 {
-  return otherfile_buf(curbuf, ffname, NULL, false);
+  return otherfile_buf(curbuf, (char *)ffname, NULL, false);
 }
 
 /// Check that "ffname" is not the same file as the file loaded in "buf".
@@ -2926,7 +2923,7 @@ bool otherfile(char_u *ffname)
 /// @param  ffname         full path name to check
 /// @param  file_id_p      information about the file at "ffname".
 /// @param  file_id_valid  whether a valid "file_id_p" was passed in.
-static bool otherfile_buf(buf_T *buf, char_u *ffname, FileID *file_id_p, bool file_id_valid)
+static bool otherfile_buf(buf_T *buf, char *ffname, FileID *file_id_p, bool file_id_valid)
   FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
 {
   // no name is different
@@ -2941,7 +2938,7 @@ static bool otherfile_buf(buf_T *buf, char_u *ffname, FileID *file_id_p, bool fi
     // If no struct stat given, get it now
     if (file_id_p == NULL) {
       file_id_p = &file_id;
-      file_id_valid = os_fileid((char *)ffname, file_id_p);
+      file_id_valid = os_fileid(ffname, file_id_p);
     }
     if (!file_id_valid) {
       // file_id not valid, assume files are different.
@@ -2995,7 +2992,7 @@ static bool buf_same_file_id(buf_T *buf, FileID *file_id)
 /// @param fullname  when non-zero print full path
 void fileinfo(int fullname, int shorthelp, int dont_truncate)
 {
-  char_u *name;
+  char *name;
   int n;
   char *p;
   char *buffer;
@@ -3015,11 +3012,11 @@ void fileinfo(int fullname, int shorthelp, int dont_truncate)
     STRLCPY(p, buf_spname(curbuf), IOSIZE - (p - buffer));
   } else {
     if (!fullname && curbuf->b_fname != NULL) {
-      name = (char_u *)curbuf->b_fname;
+      name = curbuf->b_fname;
     } else {
-      name = curbuf->b_ffname;
+      name = (char *)curbuf->b_ffname;
     }
-    home_replace(shorthelp ? curbuf : NULL, name, (char_u *)p,
+    home_replace(shorthelp ? curbuf : NULL, name, p,
                  (size_t)(IOSIZE - (p - buffer)), true);
   }
 
@@ -3069,7 +3066,7 @@ void fileinfo(int fullname, int shorthelp, int dont_truncate)
               (int)curwin->w_cursor.col + 1, (int)curwin->w_virtcol + 1);
   }
 
-  (void)append_arg_number(curwin, (char_u *)buffer, IOSIZE, !shortmess(SHM_FILE));
+  (void)append_arg_number(curwin, buffer, IOSIZE, !shortmess(SHM_FILE));
 
   if (dont_truncate) {
     // Temporarily set msg_scroll to avoid the message being truncated.
@@ -3103,14 +3100,14 @@ void col_print(char_u *buf, size_t buflen, int col, int vcol)
   }
 }
 
-static char_u *lasttitle = NULL;
-static char_u *lasticon = NULL;
+static char *lasttitle = NULL;
+static char *lasticon = NULL;
 
 /// Put the title name in the title bar and icon of the window.
 void maketitle(void)
 {
-  char_u *title_str = NULL;
-  char_u *icon_str = NULL;
+  char *title_str = NULL;
+  char *icon_str = NULL;
   int maxlen = 0;
   int len;
   int mustset;
@@ -3145,14 +3142,13 @@ void maketitle(void)
         build_stl_str_hl(curwin, buf, sizeof(buf),
                          (char *)p_titlestring, use_sandbox,
                          0, maxlen, NULL, NULL);
-        title_str = (char_u *)buf;
+        title_str = buf;
         if (called_emsg) {
-          set_string_option_direct("titlestring", -1, (char_u *)"",
-                                   OPT_FREE, SID_ERROR);
+          set_string_option_direct("titlestring", -1, "", OPT_FREE, SID_ERROR);
         }
         called_emsg |= save_called_emsg;
       } else {
-        title_str = p_titlestring;
+        title_str = (char *)p_titlestring;
       }
     } else {
       // Format: "fname + (path) (1 of 2) - VIM".
@@ -3195,7 +3191,7 @@ void maketitle(void)
         // Get path of file, replace home dir with ~.
         *buf_p++ = ' ';
         *buf_p++ = '(';
-        home_replace(curbuf, curbuf->b_ffname, (char_u *)buf_p,
+        home_replace(curbuf, (char *)curbuf->b_ffname, buf_p,
                      (SPACE_FOR_DIR - (size_t)(buf_p - buf)), true);
 #ifdef BACKSLASH_IN_FILENAME
         // Avoid "c:/name" to be reduced to "c".
@@ -3232,18 +3228,17 @@ void maketitle(void)
         *buf_p = NUL;
       }
 
-      append_arg_number(curwin, (char_u *)buf_p,
-                        (int)(SPACE_FOR_ARGNR - (size_t)(buf_p - buf)), false);
+      append_arg_number(curwin, buf_p, (int)(SPACE_FOR_ARGNR - (size_t)(buf_p - buf)), false);
 
       xstrlcat(buf_p, " - NVIM", (sizeof(buf) - (size_t)(buf_p - buf)));
 
       if (maxlen > 0) {
         // Make it shorter by removing a bit in the middle.
-        if (vim_strsize((char_u *)buf) > maxlen) {
+        if (vim_strsize(buf) > maxlen) {
           trunc_string((char_u *)buf, (char_u *)buf, maxlen, sizeof(buf));
         }
       }
-      title_str = (char_u *)buf;
+      title_str = buf;
 #undef SPACE_FOR_FNAME
 #undef SPACE_FOR_DIR
 #undef SPACE_FOR_ARGNR
@@ -3252,7 +3247,7 @@ void maketitle(void)
   mustset = value_change(title_str, &lasttitle);
 
   if (p_icon) {
-    icon_str = (char_u *)buf;
+    icon_str = buf;
     if (*p_iconstring != NUL) {
       if (stl_syntax & STL_IN_ICON) {
         int use_sandbox = false;
@@ -3260,34 +3255,33 @@ void maketitle(void)
 
         use_sandbox = was_set_insecurely(curwin, "iconstring", 0);
         called_emsg = false;
-        build_stl_str_hl(curwin, (char *)icon_str, sizeof(buf),
+        build_stl_str_hl(curwin, icon_str, sizeof(buf),
                          (char *)p_iconstring, use_sandbox,
                          0, 0, NULL, NULL);
         if (called_emsg) {
-          set_string_option_direct("iconstring", -1,
-                                   (char_u *)"", OPT_FREE, SID_ERROR);
+          set_string_option_direct("iconstring", -1, "", OPT_FREE, SID_ERROR);
         }
         called_emsg |= save_called_emsg;
       } else {
-        icon_str = p_iconstring;
+        icon_str = (char *)p_iconstring;
       }
     } else {
-      char_u *buf_p;
+      char *buf_p;
       if (buf_spname(curbuf) != NULL) {
         buf_p = buf_spname(curbuf);
       } else {                        // use file name only in icon
-        buf_p = (char_u *)path_tail((char *)curbuf->b_ffname);
+        buf_p = path_tail((char *)curbuf->b_ffname);
       }
       *icon_str = NUL;
       // Truncate name at 100 bytes.
       len = (int)STRLEN(buf_p);
       if (len > 100) {
         len -= 100;
-        len += mb_tail_off(buf_p, buf_p + len) + 1;
+        len += mb_tail_off((char_u *)buf_p, (char_u *)buf_p + len) + 1;
         buf_p += len;
       }
       STRCPY(icon_str, buf_p);
-      trans_characters(icon_str, IOSIZE);
+      trans_characters((char_u *)icon_str, IOSIZE);
     }
   }
 
@@ -3306,7 +3300,7 @@ void maketitle(void)
 /// @param[in,out]  last  current title string
 ///
 /// @return  true if resettitle() is to be called.
-static bool value_change(char_u *str, char_u **last)
+static bool value_change(char *str, char **last)
   FUNC_ATTR_WARN_UNUSED_RESULT
 {
   if ((str == NULL) != (*last == NULL)
@@ -3316,7 +3310,7 @@ static bool value_change(char_u *str, char_u **last)
       *last = NULL;
       resettitle();
     } else {
-      *last = vim_strsave(str);
+      *last = xstrdup(str);
       return true;
     }
   }
@@ -3326,8 +3320,8 @@ static bool value_change(char_u *str, char_u **last)
 /// Set current window title
 void resettitle(void)
 {
-  ui_call_set_icon(cstr_as_string((char *)lasticon));
-  ui_call_set_title(cstr_as_string((char *)lasttitle));
+  ui_call_set_icon(cstr_as_string(lasticon));
+  ui_call_set_title(cstr_as_string(lasttitle));
   ui_flush();
 }
 
@@ -3431,7 +3425,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
   }
 
   // Get line & check if empty (cursorpos will show "0-1").
-  const char_u *line_ptr = ml_get_buf(wp->w_buffer, lnum, false);
+  const char *line_ptr = (char *)ml_get_buf(wp->w_buffer, lnum, false);
   bool empty_line = (*line_ptr == NUL);
 
   // Get the byte value now, in case we need it below. This is more
@@ -3445,7 +3439,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
     wp->w_cursor.coladd = 0;
     byteval = 0;
   } else {
-    byteval = utf_ptr2char((char *)line_ptr + wp->w_cursor.col);
+    byteval = utf_ptr2char(line_ptr + wp->w_cursor.col);
   }
 
   int groupdepth = 0;
@@ -3522,7 +3516,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
         continue;
       }
       stl_items[curitem].type = Separate;
-      stl_items[curitem++].start = (char_u *)out_p;
+      stl_items[curitem++].start = out_p;
       continue;
     }
 
@@ -3530,7 +3524,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
     if (*fmt_p == STL_TRUNCMARK) {
       fmt_p++;
       stl_items[curitem].type = Trunc;
-      stl_items[curitem++].start = (char_u *)out_p;
+      stl_items[curitem++].start = out_p;
       continue;
     }
 
@@ -3546,7 +3540,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
       // Determine how long the group is.
       // Note: We set the current output position to null
       //       so `vim_strsize` will work.
-      char_u *t = stl_items[stl_groupitems[groupdepth]].start;
+      char *t = stl_items[stl_groupitems[groupdepth]].start;
       *out_p = NUL;
       long group_len = vim_strsize(t);
 
@@ -3579,7 +3573,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
         }
         if (n == curitem && group_start_userhl == group_end_userhl) {
           // empty group
-          out_p = (char *)t;
+          out_p = t;
           group_len = 0;
           for (n = stl_groupitems[groupdepth] + 1; n < curitem; n++) {
             // do not use the highlighting from the removed group
@@ -3589,7 +3583,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
             // adjust the start position of TabPage to the next
             // item position
             if (stl_items[n].type == TabPage) {
-              stl_items[n].start = (char_u *)out_p;
+              stl_items[n].start = out_p;
             }
           }
         }
@@ -3604,7 +3598,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
         long n = 0;
         while (group_len >= stl_items[stl_groupitems[groupdepth]].maxwid) {
           group_len -= ptr2cells(t + n);
-          n += utfc_ptr2len((char *)t + n);
+          n += utfc_ptr2len(t + n);
         }
         // }
 
@@ -3612,7 +3606,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
         *t = '<';
 
         // { Move the truncated output
-        memmove(t + 1, t + n, (size_t)((char_u *)out_p - (t + n)));
+        memmove(t + 1, t + n, (size_t)(out_p - (t + n)));
         out_p = out_p - n + 1;
         // Fill up space left over by half a double-wide char.
         while (++group_len < stl_items[stl_groupitems[groupdepth]].minwid) {
@@ -3646,7 +3640,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
         } else {
           // { Move the group to the right
           group_len = (min_group_width - group_len) * utf_char2len(fillchar);
-          memmove(t + group_len, t, (size_t)((char_u *)out_p - t));
+          memmove(t + group_len, t, (size_t)(out_p - t));
           if (out_p + group_len >= (out_end_p + 1)) {
             group_len = (long)(out_end_p - out_p);
           }
@@ -3692,7 +3686,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
     // to denote the styling to use.
     if (*fmt_p == STL_USER_HL) {
       stl_items[curitem].type = Highlight;
-      stl_items[curitem].start = (char_u *)out_p;
+      stl_items[curitem].start = out_p;
       stl_items[curitem].minwid = minwid > 9 ? 1 : minwid;
       fmt_p++;
       curitem++;
@@ -3738,7 +3732,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
         }
       }
       stl_items[curitem].type = TabPage;
-      stl_items[curitem].start = (char_u *)out_p;
+      stl_items[curitem].start = out_p;
       stl_items[curitem].minwid = minwid;
       fmt_p++;
       curitem++;
@@ -3755,7 +3749,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
         break;
       }
       stl_items[curitem].type = ClickFunc;
-      stl_items[curitem].start = (char_u *)out_p;
+      stl_items[curitem].start = out_p;
       stl_items[curitem].cmd = xmemdupz(t, (size_t)(fmt_p - t));
       stl_items[curitem].minwid = minwid;
       fmt_p++;
@@ -3780,7 +3774,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
     if (*fmt_p == '(') {
       stl_groupitems[groupdepth++] = curitem;
       stl_items[curitem].type = Group;
-      stl_items[curitem].start = (char_u *)out_p;
+      stl_items[curitem].start = out_p;
       stl_items[curitem].minwid = minwid;
       stl_items[curitem].maxwid = maxwid;
       fmt_p++;
@@ -3821,9 +3815,9 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
       if (buf_spname(wp->w_buffer) != NULL) {
         STRLCPY(NameBuff, buf_spname(wp->w_buffer), MAXPATHL);
       } else {
-        char_u *t = (opt == STL_FULLPATH) ? wp->w_buffer->b_ffname
-                                          : (char_u *)wp->w_buffer->b_fname;
-        home_replace(wp->w_buffer, t, NameBuff, MAXPATHL, true);
+        char *t = (opt == STL_FULLPATH) ? (char *)wp->w_buffer->b_ffname
+                                          : wp->w_buffer->b_fname;
+        home_replace(wp->w_buffer, t, (char *)NameBuff, MAXPATHL, true);
       }
       trans_characters(NameBuff, MAXPATHL);
       if (opt != STL_FILENAME) {
@@ -3912,18 +3906,14 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
         size_t parsed_usefmt = (size_t)(block_start - usefmt);
         size_t str_length = STRLEN(str);
         size_t fmt_length = STRLEN(fmt_p);
-        size_t new_fmt_len = parsed_usefmt
-                             + str_length + fmt_length + 3;
-        char_u *new_fmt = (char_u *)xmalloc(new_fmt_len * sizeof(char_u));
-        char_u *new_fmt_p = new_fmt;
-
-        new_fmt_p = (char_u *)memcpy(new_fmt_p, usefmt, parsed_usefmt)
-                    + parsed_usefmt;
-        new_fmt_p = (char_u *)memcpy(new_fmt_p, str, str_length)
-                    + str_length;
-        new_fmt_p = (char_u *)memcpy(new_fmt_p, "%}", 2) + 2;
-        new_fmt_p = (char_u *)memcpy(new_fmt_p, fmt_p, fmt_length)
-                    + fmt_length;
+        size_t new_fmt_len = parsed_usefmt + str_length + fmt_length + 3;
+        char *new_fmt = xmalloc(new_fmt_len * sizeof(char));
+        char *new_fmt_p = new_fmt;
+
+        new_fmt_p = (char *)memcpy(new_fmt_p, usefmt, parsed_usefmt) + parsed_usefmt;
+        new_fmt_p = (char *)memcpy(new_fmt_p, str, str_length) + str_length;
+        new_fmt_p = (char *)memcpy(new_fmt_p, "%}", 2) + 2;
+        new_fmt_p = (char *)memcpy(new_fmt_p, fmt_p, fmt_length) + fmt_length;
         *new_fmt_p = 0;
         new_fmt_p = NULL;
 
@@ -3931,7 +3921,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
           xfree(usefmt);
         }
         XFREE_CLEAR(str);
-        usefmt = (char *)new_fmt;
+        usefmt = new_fmt;
         fmt_p = usefmt + parsed_usefmt;
         evaldepth++;
         continue;
@@ -3974,7 +3964,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
       // Store the position percentage in our temporary buffer.
       // Note: We cannot store the value in `num` because
       //       `get_rel_pos` can return a named position. Ex: "Top"
-      get_rel_pos(wp, (char_u *)buf_tmp, TMPLEN);
+      get_rel_pos(wp, buf_tmp, TMPLEN);
       str = buf_tmp;
       break;
 
@@ -3989,14 +3979,14 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
 
       // Note: The call will only return true if it actually
       //       appended data to the `buf_tmp` buffer.
-      if (append_arg_number(wp, (char_u *)buf_tmp, (int)sizeof(buf_tmp), false)) {
+      if (append_arg_number(wp, buf_tmp, (int)sizeof(buf_tmp), false)) {
         str = buf_tmp;
       }
       break;
 
     case STL_KEYMAP:
       fillable = false;
-      if (get_keymap_str(wp, (char_u *)"<%s>", (char_u *)buf_tmp, TMPLEN)) {
+      if (get_keymap_str(wp, "<%s>", buf_tmp, TMPLEN)) {
         str = buf_tmp;
       }
       break;
@@ -4066,11 +4056,10 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
       // (including the comma and null terminating character)
       if (*wp->w_buffer->b_p_ft != NUL
           && STRLEN(wp->w_buffer->b_p_ft) < TMPLEN - 2) {
-        vim_snprintf(buf_tmp, sizeof(buf_tmp), ",%s",
-                     wp->w_buffer->b_p_ft);
+        vim_snprintf(buf_tmp, sizeof(buf_tmp), ",%s", wp->w_buffer->b_p_ft);
         // Uppercase the file extension
-        for (char_u *t = (char_u *)buf_tmp; *t != 0; t++) {
-          *t = (char_u)TOUPPER_LOC(*t);
+        for (char *t = buf_tmp; *t != 0; t++) {
+          *t = (char)TOUPPER_LOC(*t);
         }
         str = buf_tmp;
       }
@@ -4121,8 +4110,8 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
       // Create a highlight item based on the name
       if (*fmt_p == '#') {
         stl_items[curitem].type = Highlight;
-        stl_items[curitem].start = (char_u *)out_p;
-        stl_items[curitem].minwid = -syn_name2id_len((char_u *)t, (size_t)(fmt_p - t));
+        stl_items[curitem].start = out_p;
+        stl_items[curitem].minwid = -syn_name2id_len(t, (size_t)(fmt_p - t));
         curitem++;
         fmt_p++;
       }
@@ -4133,7 +4122,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
     // If we made it this far, the item is normal and starts at
     // our current position in the output buffer.
     // Non-normal items would have `continued`.
-    stl_items[curitem].start = (char_u *)out_p;
+    stl_items[curitem].start = out_p;
     stl_items[curitem].type = Normal;
 
     // Copy the item string into the output buffer
@@ -4151,7 +4140,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
       }
       // }
 
-      long l = vim_strsize((char_u *)t);
+      long l = vim_strsize(t);
 
       // If this item is non-empty, record that the last thing
       // we put in the output buffer was an item
@@ -4162,7 +4151,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
       // If the item is too wide, truncate it from the beginning
       if (l > maxwid) {
         while (l >= maxwid) {
-          l -= ptr2cells((char_u *)t);
+          l -= ptr2cells(t);
           t += utfc_ptr2len(t);
         }
 
@@ -4219,8 +4208,8 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
       prevchar_isitem = true;
 
       // { Build the formatting string
-      char_u nstr[20];
-      char_u *t = nstr;
+      char nstr[20];
+      char *t = nstr;
       if (opt == STL_VIRTCOL_ALT) {
         *t++ = '-';
         minwid--;
@@ -4232,7 +4221,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
 
       // Note: The `*` means we take the width as one of the arguments
       *t++ = '*';
-      *t++ = (char_u)(base == kNumBaseHexadecimal ? 'X' : 'd');
+      *t++ = base == kNumBaseHexadecimal ? 'X' : 'd';
       *t = 0;
       // }
 
@@ -4279,9 +4268,9 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
         *++t = 0;
         // }
 
-        vim_snprintf(out_p, remaining_buf_len, (char *)nstr, 0, num, n);
+        vim_snprintf(out_p, remaining_buf_len, nstr, 0, num, n);
       } else {
-        vim_snprintf(out_p, remaining_buf_len, (char *)nstr, minwid, num);
+        vim_snprintf(out_p, remaining_buf_len, nstr, minwid, num);
       }
 
       // Advance the output buffer position to the end of the
@@ -4318,15 +4307,15 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
   // We have now processed the entire statusline format string.
   // What follows is post-processing to handle alignment and highlighting.
 
-  int width = vim_strsize((char_u *)out);
+  int width = vim_strsize(out);
   if (maxwidth > 0 && width > maxwidth) {
     // Result is too long, must truncate somewhere.
     int item_idx = 0;
-    char_u *trunc_p;
+    char *trunc_p;
 
     // If there are no items, truncate from beginning
     if (itemcnt == 0) {
-      trunc_p = (char_u *)out;
+      trunc_p = out;
 
       // Otherwise, look for the truncation item
     } else {
@@ -4349,7 +4338,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
     if (width - vim_strsize(trunc_p) >= maxwidth) {
       // Walk from the beginning of the
       // string to find the last character that will fit.
-      trunc_p = (char_u *)out;
+      trunc_p = out;
       width = 0;
       for (;;) {
         width += ptr2cells(trunc_p);
@@ -4359,7 +4348,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
 
         // Note: Only advance the pointer if the next
         //       character will fit in the available output space
-        trunc_p += utfc_ptr2len((char *)trunc_p);
+        trunc_p += utfc_ptr2len(trunc_p);
       }
 
       // Ignore any items in the statusline that occur after
@@ -4381,12 +4370,12 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
       long trunc_len = 0;
       while (width >= maxwidth) {
         width     -= ptr2cells(trunc_p + trunc_len);
-        trunc_len += utfc_ptr2len((char *)trunc_p + trunc_len);
+        trunc_len += utfc_ptr2len(trunc_p + trunc_len);
       }
       // }
 
       // { Truncate the string
-      char_u *trunc_end_p = trunc_p + trunc_len;
+      char *trunc_end_p = trunc_p + trunc_len;
       STRMOVE(trunc_p + 1, trunc_end_p);
 
       // Put a `<` to mark where we truncated at
@@ -4452,10 +4441,10 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
       for (int i = 0; i < num_separators; i++) {
         int dislocation = (i == (num_separators - 1)) ? final_spaces : standard_spaces;
         dislocation *= utf_char2len(fillchar);
-        char_u *start = stl_items[stl_separator_locations[i]].start;
-        char_u *seploc = start + dislocation;
+        char *start = stl_items[stl_separator_locations[i]].start;
+        char *seploc = start + dislocation;
         STRMOVE(seploc, start);
-        for (char_u *s = start; s < seploc;) {
+        for (char *s = start; s < seploc;) {
           MB_CHAR2BYTES(fillchar, s);
         }
 
@@ -4491,7 +4480,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
     StlClickRecord *cur_tab_rec = stl_tabtab;
     for (long l = 0; l < itemcnt; l++) {
       if (stl_items[l].type == TabPage) {
-        cur_tab_rec->start = (char *)stl_items[l].start;
+        cur_tab_rec->start = stl_items[l].start;
         if (stl_items[l].minwid == 0) {
           cur_tab_rec->def.type = kStlClickDisabled;
           cur_tab_rec->def.tabnr = 0;
@@ -4508,7 +4497,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
         cur_tab_rec->def.func = NULL;
         cur_tab_rec++;
       } else if (stl_items[l].type == ClickFunc) {
-        cur_tab_rec->start = (char *)stl_items[l].start;
+        cur_tab_rec->start = stl_items[l].start;
         cur_tab_rec->def.type = kStlClickFuncRun;
         cur_tab_rec->def.tabnr = stl_items[l].minwid;
         cur_tab_rec->def.func = stl_items[l].cmd;
@@ -4533,7 +4522,7 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, int use_san
 
 /// Get relative cursor position in window into "buf[buflen]", in the form 99%,
 /// using "Top", "Bot" or "All" when appropriate.
-void get_rel_pos(win_T *wp, char_u *buf, int buflen)
+void get_rel_pos(win_T *wp, char *buf, int buflen)
 {
   // Need at least 3 chars for writing.
   if (buflen < 3) {
@@ -4556,7 +4545,7 @@ void get_rel_pos(win_T *wp, char_u *buf, int buflen)
   } else if (above <= 0) {
     STRLCPY(buf, _("Top"), buflen);
   } else {
-    vim_snprintf((char *)buf, (size_t)buflen, "%2d%%", above > 1000000L
+    vim_snprintf(buf, (size_t)buflen, "%2d%%", above > 1000000L
                  ? (int)(above / ((above + below) / 100L))
                  : (int)(above * 100L / (above + below)));
   }
@@ -4570,7 +4559,7 @@ void get_rel_pos(win_T *wp, char_u *buf, int buflen)
 /// @param          add_file  if true, add "file" before the arg number
 ///
 /// @return  true if it was appended.
-static bool append_arg_number(win_T *wp, char_u *buf, int buflen, bool add_file)
+static bool append_arg_number(win_T *wp, char *buf, int buflen, bool add_file)
   FUNC_ATTR_NONNULL_ALL
 {
   // Nothing to do
@@ -4578,7 +4567,7 @@ static bool append_arg_number(win_T *wp, char_u *buf, int buflen, bool add_file)
     return false;
   }
 
-  char_u *p = buf + STRLEN(buf);  // go to the end of the buffer
+  char *p = buf + STRLEN(buf);  // go to the end of the buffer
 
   // Early out if the string is getting too long
   if (p - buf + 35 >= buflen) {
@@ -4591,7 +4580,7 @@ static bool append_arg_number(win_T *wp, char_u *buf, int buflen, bool add_file)
     STRCPY(p, "file ");
     p += 5;
   }
-  vim_snprintf((char *)p, (size_t)(buflen - (p - buf)),
+  vim_snprintf(p, (size_t)(buflen - (p - buf)),
                wp->w_arg_idx_invalid
                ? "(%d) of %d)"
                : "%d of %d)", wp->w_arg_idx + 1, ARGCOUNT);
@@ -4604,7 +4593,7 @@ static bool append_arg_number(win_T *wp, char_u *buf, int buflen, bool add_file)
 /// allocated memory.
 /// The "*ffname" and "*sfname" pointer values on call will not be freed.
 /// Note that the resulting "*ffname" pointer should be considered not allocated.
-void fname_expand(buf_T *buf, char_u **ffname, char_u **sfname)
+void fname_expand(buf_T *buf, char **ffname, char **sfname)
 {
   if (*ffname == NULL) {  // no file name given, nothing to do
     return;
@@ -4612,7 +4601,7 @@ void fname_expand(buf_T *buf, char_u **ffname, char_u **sfname)
   if (*sfname == NULL) {  // no short file name given, use ffname
     *sfname = *ffname;
   }
-  *ffname = (char_u *)fix_fname((char *)(*ffname));     // expand to full path
+  *ffname = fix_fname((*ffname));     // expand to full path
 
 #ifdef WIN32
   if (!buf->b_p_bin) {
@@ -4620,24 +4609,24 @@ void fname_expand(buf_T *buf, char_u **ffname, char_u **sfname)
     char *rfname = os_resolve_shortcut((const char *)(*ffname));
     if (rfname != NULL) {
       xfree(*ffname);
-      *ffname = (char_u *)rfname;
-      *sfname = (char_u *)rfname;
+      *ffname = rfname;
+      *sfname = rfname;
     }
   }
 #endif
 }
 
 /// Get the file name for an argument list entry.
-char_u *alist_name(aentry_T *aep)
+char *alist_name(aentry_T *aep)
 {
   buf_T *bp;
 
   // Use the name from the associated buffer if it exists.
   bp = buflist_findnr(aep->ae_fnum);
   if (bp == NULL || bp->b_fname == NULL) {
-    return aep->ae_fname;
+    return (char *)aep->ae_fname;
   }
-  return (char_u *)bp->b_fname;
+  return bp->b_fname;
 }
 
 /// do_arg_all(): Open up to 'count' windows, one for each argument.
@@ -4646,7 +4635,7 @@ char_u *alist_name(aentry_T *aep)
 /// @param keep_tabs  keep current tabs, for ":tab drop file"
 void do_arg_all(int count, int forceit, int keep_tabs)
 {
-  char_u *opened;          // Array of weight for which args are open:
+  uint8_t *opened;         // Array of weight for which args are open:
                            //  0: not opened
                            //  1: opened in other tab
                            //  2: opened in curtab
@@ -4710,7 +4699,7 @@ void do_arg_all(int count, int forceit, int keep_tabs)
           if (i < alist->al_ga.ga_len
               && (AARGLIST(alist)[i].ae_fnum == buf->b_fnum
                   || path_full_compare(alist_name(&AARGLIST(alist)[i]),
-                                       buf->b_ffname,
+                                       (char *)buf->b_ffname,
                                        true, true) & kEqualFiles)) {
             int weight = 1;
 
@@ -4722,7 +4711,7 @@ void do_arg_all(int count, int forceit, int keep_tabs)
             }
 
             if (weight > (int)opened[i]) {
-              opened[i] = (char_u)weight;
+              opened[i] = (uint8_t)weight;
               if (i == 0) {
                 if (new_curwin != NULL) {
                   new_curwin->w_arg_idx = opened_len;
@@ -4854,7 +4843,7 @@ void do_arg_all(int count, int forceit, int keep_tabs)
         new_curwin = curwin;
         new_curtab = curtab;
       }
-      (void)do_ecmd(0, (char *)alist_name(&AARGLIST(alist)[i]), NULL, NULL, ECMD_ONE,
+      (void)do_ecmd(0, alist_name(&AARGLIST(alist)[i]), NULL, NULL, ECMD_ONE,
                     ((buf_hide(curwin->w_buffer)
                       || bufIsChanged(curwin->w_buffer))
                      ? ECMD_HIDE : 0) + ECMD_OLDBUF,
@@ -5131,18 +5120,18 @@ void do_modelines(int flags)
 /// @param flags  Same as for do_modelines().
 static int chk_modeline(linenr_T lnum, int flags)
 {
-  char_u *s;
-  char_u *e;
-  char_u *linecopy;                // local copy of any modeline found
+  char *s;
+  char *e;
+  char *linecopy;                // local copy of any modeline found
   int prev;
   intmax_t vers;
   int end;
   int retval = OK;
-  char_u *save_sourcing_name;
+  char *save_sourcing_name;
   linenr_T save_sourcing_lnum;
 
   prev = -1;
-  for (s = ml_get(lnum); *s != NUL; s++) {
+  for (s = (char *)ml_get(lnum); *s != NUL; s++) {
     if (prev == -1 || ascii_isspace(prev)) {
       if ((prev != -1 && STRNCMP(s, "ex:", (size_t)3) == 0)
           || STRNCMP(s, "vi:", (size_t)3) == 0) {
@@ -5171,7 +5160,7 @@ static int chk_modeline(linenr_T lnum, int flags)
         }
       }
     }
-    prev = *s;
+    prev = (uint8_t)(*s);
   }
 
   if (!*s) {
@@ -5182,16 +5171,16 @@ static int chk_modeline(linenr_T lnum, int flags)
     s++;
   } while (s[-1] != ':');
 
-  s = linecopy = vim_strsave(s);      // copy the line, it will change
+  s = linecopy = xstrdup(s);      // copy the line, it will change
 
   save_sourcing_lnum = sourcing_lnum;
-  save_sourcing_name = (char_u *)sourcing_name;
+  save_sourcing_name = sourcing_name;
   sourcing_lnum = lnum;               // prepare for emsg()
   sourcing_name = "modelines";
 
   end = false;
   while (end == false) {
-    s = (char_u *)skipwhite((char *)s);
+    s = skipwhite(s);
     if (*s == NUL) {
       break;
     }
@@ -5218,7 +5207,7 @@ static int chk_modeline(linenr_T lnum, int flags)
         break;
       }
       end = true;
-      s = (char_u *)vim_strchr((char *)s, ' ') + 1;
+      s = vim_strchr(s, ' ') + 1;
     }
     *e = NUL;                         // truncate the set command
 
@@ -5243,7 +5232,7 @@ static int chk_modeline(linenr_T lnum, int flags)
   }
 
   sourcing_lnum = save_sourcing_lnum;
-  sourcing_name = (char *)save_sourcing_name;
+  sourcing_name = save_sourcing_name;
 
   xfree(linecopy);
 
@@ -5328,26 +5317,26 @@ bool buf_hide(const buf_T *const buf)
 
 /// @return  special buffer name or
 ///          NULL when the buffer has a normal file name.
-char_u *buf_spname(buf_T *buf)
+char *buf_spname(buf_T *buf)
 {
   if (bt_quickfix(buf)) {
     // Differentiate between the quickfix and location list buffers using
     // the buffer number stored in the global quickfix stack.
     if (buf->b_fnum == qf_stack_get_bufnr()) {
-      return (char_u *)_(msg_qflist);
+      return _(msg_qflist);
     }
-    return (char_u *)_(msg_loclist);
+    return _(msg_loclist);
   }
   // There is no _file_ when 'buftype' is "nofile", b_sfname
   // contains the name as specified by the user.
   if (bt_nofile(buf)) {
     if (buf->b_fname != NULL) {
-      return (char_u *)buf->b_fname;
+      return buf->b_fname;
     }
     if (bt_prompt(buf)) {
-      return (char_u *)_("[Prompt]");
+      return _("[Prompt]");
     }
-    return (char_u *)_("[Scratch]");
+    return _("[Scratch]");
   }
   if (buf->b_fname == NULL) {
     return buf_get_fname(buf);
@@ -5530,13 +5519,13 @@ int buf_signcols(buf_T *buf, int maximum)
 }
 
 /// Get "buf->b_fname", use "[No Name]" if it is NULL.
-char_u *buf_get_fname(const buf_T *buf)
+char *buf_get_fname(const buf_T *buf)
   FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ALL
 {
   if (buf->b_fname == NULL) {
-    return (char_u *)_("[No Name]");
+    return _("[No Name]");
   }
-  return (char_u *)buf->b_fname;
+  return buf->b_fname;
 }
 
 /// Set 'buflisted' for curbuf to "on" and trigger autocommands if it changed.
@@ -5632,7 +5621,7 @@ void wipe_buffer(buf_T *buf, bool aucmd)
 void buf_open_scratch(handle_T bufnr, char *bufname)
 {
   (void)do_ecmd((int)bufnr, NULL, NULL, NULL, ECMD_ONE, ECMD_HIDE, NULL);
-  (void)setfname(curbuf, (char_u *)bufname, NULL, true);
+  (void)setfname(curbuf, bufname, NULL, true);
   set_option_value("bh", 0L, "hide", OPT_LOCAL);
   set_option_value("bt", 0L, "nofile", OPT_LOCAL);
   set_option_value("swf", 0L, NULL, OPT_LOCAL);
diff --git a/src/nvim/buffer_defs.h b/src/nvim/buffer_defs.h
index f1dd8aadeb..5d1135f91c 100644
--- a/src/nvim/buffer_defs.h
+++ b/src/nvim/buffer_defs.h
@@ -373,7 +373,7 @@ struct mapblock {
 /// Used for highlighting in the status line.
 typedef struct stl_hlrec stl_hlrec_t;
 struct stl_hlrec {
-  char_u *start;
+  char *start;
   int userhl;                   // 0: no HL, 1-9: User HL, < 0 for syn ID
 };
 
@@ -381,7 +381,7 @@ struct stl_hlrec {
 typedef struct stl_item stl_item_t;
 struct stl_item {
   // Where the item starts in the status line output buffer
-  char_u *start;
+  char *start;
   // Function to run for ClickFunc items.
   char *cmd;
   // The minimum width of the item
diff --git a/src/nvim/change.c b/src/nvim/change.c
index c0796386f1..a383fe6bb3 100644
--- a/src/nvim/change.c
+++ b/src/nvim/change.c
@@ -1393,7 +1393,7 @@ int open_line(int dir, int flags, int second_line_indent, bool *did_do_comment)
 
             while (old_size < repl_size && p > leader) {
               MB_PTR_BACK(leader, p);
-              old_size += ptr2cells(p);
+              old_size += ptr2cells((char *)p);
             }
             l = lead_repl_len - (int)(endp - p);
             if (l != 0) {
@@ -1413,7 +1413,7 @@ int open_line(int dir, int flags, int second_line_indent, bool *did_do_comment)
 
             if (l > 1) {
               p -= l;
-              if (ptr2cells(p) > 1) {
+              if (ptr2cells((char *)p) > 1) {
                 p[1] = ' ';
                 l--;
               }
@@ -1463,7 +1463,7 @@ int open_line(int dir, int flags, int second_line_indent, bool *did_do_comment)
                 int l = utfc_ptr2len((char *)p);
 
                 if (l > 1) {
-                  if (ptr2cells(p) > 1) {
+                  if (ptr2cells((char *)p) > 1) {
                     // Replace a double-wide char with
                     // two spaces
                     l--;
diff --git a/src/nvim/charset.c b/src/nvim/charset.c
index 9bc0bef446..885ebca214 100644
--- a/src/nvim/charset.c
+++ b/src/nvim/charset.c
@@ -687,11 +687,12 @@ int char2cells(int c)
 /// @param p
 ///
 /// @return number of display cells.
-int ptr2cells(const char_u *p)
+int ptr2cells(const char *p_in)
 {
+  uint8_t *p = (uint8_t *)p_in;
   // For UTF-8 we need to look at more bytes if the first byte is >= 0x80.
   if (*p >= 0x80) {
-    return utf_ptr2cells((char *)p);
+    return utf_ptr2cells(p_in);
   }
 
   // For DBCS we can tell the cell count from the first byte.
@@ -706,9 +707,9 @@ int ptr2cells(const char_u *p)
 /// @param s
 ///
 /// @return number of character cells.
-int vim_strsize(char_u *s)
+int vim_strsize(char *s)
 {
-  return vim_strnsize(s, MAXCOL);
+  return vim_strnsize((char_u *)s, MAXCOL);
 }
 
 /// Return the number of character cells string "s[len]" will take on the
@@ -726,7 +727,7 @@ int vim_strnsize(char_u *s, int len)
   int size = 0;
   while (*s != NUL && --len >= 0) {
     int l = utfc_ptr2len((char *)s);
-    size += ptr2cells(s);
+    size += ptr2cells((char *)s);
     s += l;
     len -= l - 1;
   }
@@ -1332,10 +1333,10 @@ char_u *skip_to_newline(const char_u *const p)
 /// @param[out]  nr  Number read from the string.
 ///
 /// @return true on success, false on error/overflow
-bool try_getdigits(char_u **pp, intmax_t *nr)
+bool try_getdigits(char **pp, intmax_t *nr)
 {
   errno = 0;
-  *nr = strtoimax((char *)(*pp), (char **)pp, 10);
+  *nr = strtoimax(*pp, pp, 10);
   if (errno == ERANGE && (*nr == INTMAX_MIN || *nr == INTMAX_MAX)) {
     return false;
   }
@@ -1353,7 +1354,7 @@ bool try_getdigits(char_u **pp, intmax_t *nr)
 intmax_t getdigits(char_u **pp, bool strict, intmax_t def)
 {
   intmax_t number;
-  int ok = try_getdigits(pp, &number);
+  int ok = try_getdigits((char **)pp, &number);
   if (strict && !ok) {
     abort();
   }
diff --git a/src/nvim/debugger.c b/src/nvim/debugger.c
index 29dcddfc0d..803427dd17 100644
--- a/src/nvim/debugger.c
+++ b/src/nvim/debugger.c
@@ -687,7 +687,7 @@ void ex_breaklist(exarg_T *eap)
     for (int i = 0; i < dbg_breakp.ga_len; i++) {
       struct debuggy *bp = &BREAKP(i);
       if (bp->dbg_type == DBG_FILE) {
-        home_replace(NULL, bp->dbg_name, NameBuff, MAXPATHL, true);
+        home_replace(NULL, (char *)bp->dbg_name, (char *)NameBuff, MAXPATHL, true);
       }
       if (bp->dbg_type != DBG_EXPR) {
         smsg(_("%3d  %s %s  line %" PRId64),
diff --git a/src/nvim/diff.c b/src/nvim/diff.c
index 700e79ac75..f22933ec3c 100644
--- a/src/nvim/diff.c
+++ b/src/nvim/diff.c
@@ -1408,8 +1408,7 @@ void diff_win_options(win_T *wp, int addbuf)
     }
     wp->w_p_fdm_save = vim_strsave(wp->w_p_fdm);
   }
-  set_string_option_direct("fdm", -1, (char_u *)"diff",
-                           OPT_LOCAL | OPT_FREE, 0);
+  set_string_option_direct("fdm", -1, "diff", OPT_LOCAL | OPT_FREE, 0);
   curwin = old_curwin;
   curbuf = curwin->w_buffer;
 
diff --git a/src/nvim/digraph.c b/src/nvim/digraph.c
index 99e99a8a9e..cbff15c84a 100644
--- a/src/nvim/digraph.c
+++ b/src/nvim/digraph.c
@@ -1846,7 +1846,7 @@ static void printdigraph(const digr_T *dp, result_T *previous)
     *p++ = dp->char2;
     *p++ = ' ';
     *p = NUL;
-    msg_outtrans(buf);
+    msg_outtrans((char *)buf);
     p = buf;
 
     // add a space to draw a composing char on
@@ -1863,7 +1863,7 @@ static void printdigraph(const digr_T *dp, result_T *previous)
     }
     assert(p >= buf);
     vim_snprintf((char *)p, sizeof(buf) - (size_t)(p - buf), " %3d", dp->result);
-    msg_outtrans(buf);
+    msg_outtrans((char *)buf);
   }
 }
 
diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index 47d07e457f..1223d98fbf 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -4223,7 +4223,7 @@ static int ins_compl_get_exp(pos_T *ini)
         msg_hist_off = true;  // reset in msg_trunc_attr()
         vim_snprintf((char *)IObuff, IOSIZE, _("Scanning: %s"),
                      ins_buf->b_fname == NULL
-                     ? buf_spname(ins_buf)
+                     ? (char_u *)buf_spname(ins_buf)
                      : ins_buf->b_sfname == NULL
                      ? (char_u *)ins_buf->b_fname
                      : ins_buf->b_sfname);
@@ -4831,15 +4831,15 @@ static int ins_compl_next(int allow_get_expansion, int count, int insert_match,
    */
   if (compl_shown_match->cp_fname != NULL) {
     char *lead = _("match in file");
-    int space = sc_col - vim_strsize((char_u *)lead) - 2;
-    char_u *s;
-    char_u *e;
+    int space = sc_col - vim_strsize(lead) - 2;
+    char *s;
+    char *e;
 
     if (space > 0) {
       // We need the tail that fits.  With double-byte encoding going
       // back from the end is very slow, thus go from the start and keep
       // the text that fits in "space" between "s" and "e".
-      for (s = e = compl_shown_match->cp_fname; *e != NUL; MB_PTR_ADV(e)) {
+      for (s = e = (char *)compl_shown_match->cp_fname; *e != NUL; MB_PTR_ADV(e)) {
         space -= ptr2cells(e);
         while (space < 0) {
           space += ptr2cells(s);
@@ -4848,7 +4848,7 @@ static int ins_compl_next(int allow_get_expansion, int count, int insert_match,
       }
       msg_hist_off = true;
       vim_snprintf((char *)IObuff, IOSIZE, "%s %s%s", lead,
-                   s > compl_shown_match->cp_fname ? "<" : "", s);
+                   (char_u *)s > compl_shown_match->cp_fname ? "<" : "", s);
       msg((char *)IObuff);
       msg_hist_off = false;
       redraw_cmdline = false;     // don't overwrite!
@@ -6807,15 +6807,15 @@ void beginline(int flags)
 
 int oneright(void)
 {
-  char_u *ptr;
+  char *ptr;
   int l;
 
   if (virtual_active()) {
     pos_T prevpos = curwin->w_cursor;
 
     // Adjust for multi-wide char (excluding TAB)
-    ptr = get_cursor_pos_ptr();
-    coladvance(getviscol() + ((*ptr != TAB && vim_isprintc(utf_ptr2char((char *)ptr))) ?
+    ptr = (char *)get_cursor_pos_ptr();
+    coladvance(getviscol() + ((*ptr != TAB && vim_isprintc(utf_ptr2char(ptr))) ?
                               ptr2cells(ptr) : 1));
     curwin->w_set_curswant = true;
     // Return OK if the cursor moved, FAIL otherwise (at window edge).
@@ -6823,12 +6823,12 @@ int oneright(void)
             || prevpos.coladd != curwin->w_cursor.coladd) ? OK : FAIL;
   }
 
-  ptr = get_cursor_pos_ptr();
+  ptr = (char *)get_cursor_pos_ptr();
   if (*ptr == NUL) {
     return FAIL;            // already at the very end
   }
 
-  l = utfc_ptr2len((char *)ptr);
+  l = utfc_ptr2len(ptr);
 
   // move "l" bytes right, but don't end up on the NUL, unless 'virtualedit'
   // contains "onemore".
@@ -6865,12 +6865,9 @@ int oneleft(void)
     }
 
     if (curwin->w_cursor.coladd == 1) {
-      char_u *ptr;
-
       // Adjust for multi-wide char (not a TAB)
-      ptr = get_cursor_pos_ptr();
-      if (*ptr != TAB && vim_isprintc(utf_ptr2char((char *)ptr))
-          && ptr2cells(ptr) > 1) {
+      char *ptr = (char *)get_cursor_pos_ptr();
+      if (*ptr != TAB && vim_isprintc(utf_ptr2char(ptr)) && ptr2cells(ptr) > 1) {
         curwin->w_cursor.coladd = 0;
       }
     }
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 7b6e954b3a..bb2404750b 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -8968,7 +8968,7 @@ static void list_one_var_a(const char *prefix, const char *name, const ptrdiff_t
     msg_putchar(' ');
   }
 
-  msg_outtrans((char_u *)string);
+  msg_outtrans((char *)string);
 
   if (type == VAR_FUNC || type == VAR_PARTIAL) {
     msg_puts("()");
@@ -10124,7 +10124,7 @@ repeat:
         os_dirname((char_u *)dirname, MAXPATHL);
         if (has_homerelative) {
           s = xstrdup(dirname);
-          home_replace(NULL, (char_u *)s, (char_u *)dirname, MAXPATHL, true);
+          home_replace(NULL, s, dirname, MAXPATHL, true);
           xfree(s);
         }
         size_t namelen = STRLEN(dirname);
@@ -10147,7 +10147,7 @@ repeat:
           }
         }
       } else {
-        home_replace(NULL, (char_u *)p, (char_u *)dirname, MAXPATHL, true);
+        home_replace(NULL, p, dirname, MAXPATHL, true);
         // Only replace it when it starts with '~'
         if (*dirname == '~') {
           s = xstrdup(dirname);
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index f7d6b016fd..b383a20af4 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -10688,7 +10688,7 @@ static void f_termopen(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   // "./…" => "/home/foo/…"
   vim_FullName(cwd, (char *)NameBuff, sizeof(NameBuff), false);
   // "/home/foo/…" => "~/…"
-  size_t len = home_replace(NULL, NameBuff, IObuff, sizeof(IObuff), true);
+  size_t len = home_replace(NULL, (char *)NameBuff, (char *)IObuff, sizeof(IObuff), true);
   // Trim slash.
   if (len != 1 && (IObuff[len - 1] == '\\' || IObuff[len - 1] == '/')) {
     IObuff[len - 1] = '\0';
@@ -10706,7 +10706,7 @@ static void f_termopen(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   // at this point the buffer has no terminal instance associated yet, so unset
   // the 'swapfile' option to ensure no swap file will be created
   curbuf->b_p_swf = false;
-  (void)setfname(curbuf, NameBuff, NULL, true);
+  (void)setfname(curbuf, (char *)NameBuff, NULL, true);
   // Save the job id and pid in b:terminal_job_{id,pid}
   Error err = ERROR_INIT;
   // deprecated: use 'channel' buffer option
diff --git a/src/nvim/eval/userfunc.c b/src/nvim/eval/userfunc.c
index 9938dc5012..8646520ec3 100644
--- a/src/nvim/eval/userfunc.c
+++ b/src/nvim/eval/userfunc.c
@@ -1044,9 +1044,8 @@ void call_user_func(ufunc_T *fp, int argcount, typval_T *argvars, typval_T *rett
             if (tofree != NULL) {
               char *s = tofree;
               char buf[MSG_BUF_LEN];
-              if (vim_strsize((char_u *)s) > MSG_BUF_CLEN) {
-                trunc_string((char_u *)s, (char_u *)buf, MSG_BUF_CLEN,
-                             sizeof(buf));
+              if (vim_strsize(s) > MSG_BUF_CLEN) {
+                trunc_string((char_u *)s, (char_u *)buf, MSG_BUF_CLEN, sizeof(buf));
                 s = buf;
               }
               msg_puts(s);
@@ -1159,7 +1158,7 @@ void call_user_func(ufunc_T *fp, int argcount, typval_T *argvars, typval_T *rett
       char *tofree = s;
       emsg_off--;
       if (s != NULL) {
-        if (vim_strsize((char_u *)s) > MSG_BUF_CLEN) {
+        if (vim_strsize(s) > MSG_BUF_CLEN) {
           trunc_string((char_u *)s, (char_u *)buf, MSG_BUF_CLEN, MSG_BUF_LEN);
           s = buf;
         }
diff --git a/src/nvim/event/socket.c b/src/nvim/event/socket.c
index 1722f0ee1f..9496a568b9 100644
--- a/src/nvim/event/socket.c
+++ b/src/nvim/event/socket.c
@@ -38,7 +38,7 @@ int socket_watcher_init(Loop *loop, SocketWatcher *watcher, const char *endpoint
     char *port = host_end + 1;
     intmax_t iport;
 
-    int ok = try_getdigits(&(char_u *){ (char_u *)port }, &iport);
+    int ok = try_getdigits(&(char *){ port }, &iport);
     if (!ok || iport < 0 || iport > UINT16_MAX) {
       ELOG("Invalid port: %s", port);
       return UV_EINVAL;
diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index 92c1b5d2c7..8016c69bcb 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -876,8 +876,7 @@ void ex_retab(exarg_T *eap)
     long *old_vts_ary = curbuf->b_p_vts_array;
 
     if (tabstop_count(old_vts_ary) > 0 || tabstop_count(new_vts_array) > 1) {
-      set_string_option_direct("vts", -1, (char_u *)new_ts_str,
-                               OPT_FREE | OPT_LOCAL, 0);
+      set_string_option_direct("vts", -1, new_ts_str, OPT_FREE | OPT_LOCAL, 0);
       curbuf->b_p_vts_array = new_vts_array;
       xfree(old_vts_ary);
     } else {
@@ -1232,7 +1231,7 @@ void do_bang(int addr_count, exarg_T *eap, bool forceit, bool do_in, bool do_out
     msg_start();
     msg_putchar(':');
     msg_putchar('!');
-    msg_outtrans((char_u *)newcmd);
+    msg_outtrans(newcmd);
     msg_clr_eos();
     ui_cursor_goto(msg_row, msg_col);
 
@@ -1738,7 +1737,7 @@ int rename_buffer(char *new_fname)
   xfname = curbuf->b_fname;
   curbuf->b_ffname = NULL;
   curbuf->b_sfname = NULL;
-  if (setfname(curbuf, (char_u *)new_fname, NULL, true) == FAIL) {
+  if (setfname(curbuf, new_fname, NULL, true) == FAIL) {
     curbuf->b_ffname = (char_u *)fname;
     curbuf->b_sfname = (char_u *)sfname;
     return FAIL;
@@ -2218,7 +2217,7 @@ int getfile(int fnum, char *ffname_arg, char *sfname_arg, int setpm, linenr_T ln
 
   if (fnum == 0) {
     // make ffname full path, set sfname
-    fname_expand(curbuf, (char_u **)&ffname, (char_u **)&sfname);
+    fname_expand(curbuf, &ffname, &sfname);
     other = otherfile((char_u *)ffname);
     free_me = ffname;                   // has been allocated, free() later
   } else {
@@ -4453,8 +4452,7 @@ skip:
   // Show 'inccommand' preview if there are matched lines.
   if (cmdpreview && !aborting()) {
     if (got_quit || profile_passed_limit(timeout)) {  // Too slow, disable.
-      set_string_option_direct("icm", -1, (char_u *)"", OPT_FREE,
-                               SID_NONE);
+      set_string_option_direct("icm", -1, "", OPT_FREE, SID_NONE);
     } else if (*p_icm != NUL && pat != NULL) {
       if (pre_hl_id == 0) {
         pre_hl_id = syn_check_group(S_LEN("Substitute"));
@@ -4742,7 +4740,7 @@ bool prepare_tagpreview(bool undo_sync)
                                                and 'cursorbind' */
       curwin->w_p_diff = false;             // no 'diff'
       set_string_option_direct("fdc", -1,     // no 'foldcolumn'
-                               (char_u *)"0", OPT_FREE, SID_NONE);
+                               "0", OPT_FREE, SID_NONE);
       return true;
     }
   }
@@ -5272,8 +5270,7 @@ int find_help_tags(const char *arg, int *num_matches, char ***matches, bool keep
 static void prepare_help_buffer(void)
 {
   curbuf->b_help = true;
-  set_string_option_direct("buftype", -1, (char_u *)"help",
-                           OPT_FREE|OPT_LOCAL, 0);
+  set_string_option_direct("buftype", -1, "help", OPT_FREE|OPT_LOCAL, 0);
 
   // Always set these options after jumping to a help tag, because the
   // user may have an autocommand that gets in the way.
@@ -5282,14 +5279,13 @@ static void prepare_help_buffer(void)
   // Only set it when needed, buf_init_chartab() is some work.
   char *p = "!-~,^*,^|,^\",192-255";
   if (STRCMP(curbuf->b_p_isk, p) != 0) {
-    set_string_option_direct("isk", -1, (char_u *)p, OPT_FREE|OPT_LOCAL, 0);
+    set_string_option_direct("isk", -1, p, OPT_FREE|OPT_LOCAL, 0);
     check_buf_options(curbuf);
     (void)buf_init_chartab(curbuf, FALSE);
   }
 
   // Don't use the global foldmethod.
-  set_string_option_direct("fdm", -1, (char_u *)"manual",
-                           OPT_FREE|OPT_LOCAL, 0);
+  set_string_option_direct("fdm", -1, "manual", OPT_FREE|OPT_LOCAL, 0);
 
   curbuf->b_p_ts = 8;         // 'tabstop' is 8.
   curwin->w_p_list = FALSE;   // No list mode.
@@ -5375,7 +5371,7 @@ void fix_help_buffer(void)
         copy_option_part((char_u **)&p, NameBuff, MAXPATHL, ",");
         char *const rt = vim_getenv("VIMRUNTIME");
         if (rt != NULL
-            && path_full_compare((char_u *)rt, NameBuff, false, true) != kEqualFiles) {
+            && path_full_compare(rt, (char *)NameBuff, false, true) != kEqualFiles) {
           int fcount;
           char **fnames;
           char *s;
@@ -5582,8 +5578,7 @@ static void helptags_one(char *dir, const char *ext, const char *tagfname, bool
   // add the "help-tags" tag.
   ga_init(&ga, (int)sizeof(char_u *), 100);
   if (add_help_tags
-      || path_full_compare((char_u *)"$VIMRUNTIME/doc",
-                           (char_u *)dir, false, true) == kEqualFiles) {
+      || path_full_compare("$VIMRUNTIME/doc", dir, false, true) == kEqualFiles) {
     size_t s_len = 18 + STRLEN(tagfname);
     s = xmalloc(s_len);
     snprintf(s, s_len, "help-tags\t%s\t1\n", tagfname);
@@ -5874,8 +5869,7 @@ static int show_sub(exarg_T *eap, pos_T old_cusr, PreviewLines *preview_lines, i
   buf_T *cmdpreview_buf = NULL;
 
   // disable file info message
-  set_string_option_direct("shm", -1, (char_u *)"F", OPT_FREE,
-                           SID_NONE);
+  set_string_option_direct("shm", -1, "F", OPT_FREE, SID_NONE);
 
   // Update the topline to ensure that main window is on the correct line
   update_topline(curwin);
@@ -5977,7 +5971,7 @@ static int show_sub(exarg_T *eap, pos_T old_cusr, PreviewLines *preview_lines, i
 
   xfree(str);
 
-  set_string_option_direct("shm", -1, (char_u *)save_shm_p, OPT_FREE, SID_NONE);
+  set_string_option_direct("shm", -1, save_shm_p, OPT_FREE, SID_NONE);
   xfree(save_shm_p);
 
   return preview ? 2 : 1;
@@ -6077,7 +6071,7 @@ void ex_oldfiles(exarg_T *eap)
       if (!message_filtered((char_u *)fname)) {
         msg_outnum(nr);
         msg_puts(": ");
-        msg_outtrans((char_u *)tv_get_string(TV_LIST_ITEM_TV(li)));
+        msg_outtrans((char *)tv_get_string(TV_LIST_ITEM_TV(li)));
         msg_clr_eos();
         msg_putchar('\n');
         ui_flush();                  // output one line at a time
diff --git a/src/nvim/ex_cmds2.c b/src/nvim/ex_cmds2.c
index 9b260f9091..621004103e 100644
--- a/src/nvim/ex_cmds2.c
+++ b/src/nvim/ex_cmds2.c
@@ -732,7 +732,7 @@ bool check_changed_any(bool hidden, bool unload)
     if ((buf->terminal && channel_job_running((uint64_t)buf->b_p_channel))
         ? semsg(_("E947: Job still running in buffer \"%s\""), buf->b_fname)
         : semsg(_("E162: No write since last change for buffer \"%s\""),
-                buf_spname(buf) != NULL ? buf_spname(buf) : (char_u *)buf->b_fname)) {
+                buf_spname(buf) != NULL ? buf_spname(buf) : buf->b_fname)) {
       save = no_wait_return;
       no_wait_return = false;
       wait_return(false);
@@ -929,8 +929,7 @@ static int do_arglist(char *str, int what, int after, bool will_edit)
 
       didone = false;
       for (match = 0; match < ARGCOUNT; match++) {
-        if (vim_regexec(&regmatch, alist_name(&ARGLIST[match]),
-                        (colnr_T)0)) {
+        if (vim_regexec(&regmatch, (char_u *)alist_name(&ARGLIST[match]), (colnr_T)0)) {
           didone = true;
           xfree(ARGLIST[match].ae_fname);
           memmove(ARGLIST + match, ARGLIST + match + 1,
@@ -993,7 +992,8 @@ static bool editing_arg_idx(win_T *win)
                != WARGLIST(win)[win->w_arg_idx].ae_fnum
                && (win->w_buffer->b_ffname == NULL
                    || !(path_full_compare(alist_name(&WARGLIST(win)[win->w_arg_idx]),
-                                          win->w_buffer->b_ffname, true, true) & kEqualFiles))));
+                                          (char *)win->w_buffer->b_ffname, true,
+                                          true) & kEqualFiles))));
 }
 
 /// Check if window "win" is editing the w_arg_idx file in its argument list.
@@ -1011,7 +1011,7 @@ void check_arg_idx(win_T *win)
         && (win->w_buffer->b_fnum == GARGLIST[GARGCOUNT - 1].ae_fnum
             || (win->w_buffer->b_ffname != NULL
                 && (path_full_compare(alist_name(&GARGLIST[GARGCOUNT - 1]),
-                                      win->w_buffer->b_ffname, true, true)
+                                      (char *)win->w_buffer->b_ffname, true, true)
                     & kEqualFiles)))) {
       arg_had_last = true;
     }
@@ -1050,7 +1050,7 @@ void ex_args(exarg_T *eap)
       // required and no wait_return().
       gotocmdline(true);
       for (int i = 0; i < ARGCOUNT; i++) {
-        items[i] = (char *)alist_name(&ARGLIST[i]);
+        items[i] = alist_name(&ARGLIST[i]);
       }
       list_in_columns((char_u **)items, ARGCOUNT, curwin->w_arg_idx);
       xfree(items);
@@ -1137,7 +1137,7 @@ void do_argfile(exarg_T *eap, int argn)
       // the same buffer
       other = true;
       if (buf_hide(curbuf)) {
-        p = fix_fname((char *)alist_name(&ARGLIST[argn]));
+        p = fix_fname(alist_name(&ARGLIST[argn]));
         other = otherfile((char_u *)p);
         xfree(p);
       }
@@ -1159,7 +1159,7 @@ void do_argfile(exarg_T *eap, int argn)
     // Edit the file; always use the last known line number.
     // When it fails (e.g. Abort for already edited file) restore the
     // argument index.
-    if (do_ecmd(0, (char *)alist_name(&ARGLIST[curwin->w_arg_idx]), NULL,
+    if (do_ecmd(0, alist_name(&ARGLIST[curwin->w_arg_idx]), NULL,
                 eap, ECMD_LAST,
                 (buf_hide(curwin->w_buffer) ? ECMD_HIDE : 0)
                 + (eap->forceit ? ECMD_FORCEIT : 0), curwin) == FAIL) {
@@ -1568,7 +1568,7 @@ char *get_arglist_name(expand_T *xp FUNC_ATTR_UNUSED, int idx)
   if (idx >= ARGCOUNT) {
     return NULL;
   }
-  return (char *)alist_name(&ARGLIST[idx]);
+  return alist_name(&ARGLIST[idx]);
 }
 
 /// ":compiler[!] {name}"
@@ -2206,11 +2206,11 @@ void ex_scriptnames(exarg_T *eap)
 
   for (int i = 1; i <= script_items.ga_len && !got_int; i++) {
     if (SCRIPT_ITEM(i).sn_name != NULL) {
-      home_replace(NULL, SCRIPT_ITEM(i).sn_name, NameBuff, MAXPATHL, true);
+      home_replace(NULL, (char *)SCRIPT_ITEM(i).sn_name, (char *)NameBuff, MAXPATHL, true);
       vim_snprintf((char *)IObuff, IOSIZE, "%3d: %s", i, NameBuff);
       if (!message_filtered(IObuff)) {
         msg_putchar('\n');
-        msg_outtrans(IObuff);
+        msg_outtrans((char *)IObuff);
         line_breakcheck();
       }
     }
diff --git a/src/nvim/ex_cmds_defs.h b/src/nvim/ex_cmds_defs.h
index 8280f99547..9350a9f60b 100644
--- a/src/nvim/ex_cmds_defs.h
+++ b/src/nvim/ex_cmds_defs.h
@@ -274,7 +274,7 @@ typedef struct {
   int cmod_verbose;  ///< 0 if not set, > 0 to set 'verbose' to cmod_verbose - 1
 
   // values for undo_cmdmod()
-  char_u *cmod_save_ei;  ///< saved value of 'eventignore'
+  char *cmod_save_ei;  ///< saved value of 'eventignore'
   int cmod_did_sandbox;  ///< set when "sandbox" was incremented
   long cmod_verbose_save;  ///< if 'verbose' was set: value of p_verbose plus one
   int cmod_save_msg_silent;  ///< if non-zero: saved value of msg_silent + 1
diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index 88177533ab..48e6dad720 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -1212,7 +1212,7 @@ static char *skip_colon_white(const char *p, bool skipleadingwhite)
 /// Set the addr type for command
 ///
 /// @param p pointer to character after command name in cmdline
-void set_cmd_addr_type(exarg_T *eap, char_u *p)
+void set_cmd_addr_type(exarg_T *eap, char *p)
 {
   // ea.addr_type for user commands is set by find_ucmd
   if (IS_USER_CMDIDX(eap->cmdidx)) {
@@ -1225,7 +1225,7 @@ void set_cmd_addr_type(exarg_T *eap, char_u *p)
   }
   // :wincmd range depends on the argument
   if (eap->cmdidx == CMD_wincmd && p != NULL) {
-    get_wincmd_addr_type(skipwhite((char *)p), eap);
+    get_wincmd_addr_type(skipwhite(p), eap);
   }
   // :.cc in quickfix window uses line number
   if ((eap->cmdidx == CMD_cc || eap->cmdidx == CMD_ll) && bt_quickfix(curbuf)) {
@@ -1453,7 +1453,7 @@ bool parse_cmdline(char *cmdline, exarg_T *eap, CmdParseInfo *cmdinfo, char **er
   }
 
   // Set command address type and parse command range
-  set_cmd_addr_type(eap, (char_u *)p);
+  set_cmd_addr_type(eap, p);
   eap->cmd = cmd;
   if (parse_cmd_address(eap, errormsg, false) == FAIL) {
     return false;
@@ -1824,7 +1824,7 @@ static char *do_one_cmd(char **cmdlinep, int flags, cstack_T *cstack, LineGetter
   // The ea.cmd pointer is updated to point to the first character following the
   // range spec. If an initial address is found, but no second, the upper bound
   // is equal to the lower.
-  set_cmd_addr_type(&ea, (char_u *)p);
+  set_cmd_addr_type(&ea, p);
 
   ea.cmd = cmd;
   if (parse_cmd_address(&ea, &errormsg, false) == FAIL) {
@@ -2667,8 +2667,8 @@ static void apply_cmdmod(cmdmod_T *cmod)
   if ((cmod->cmod_flags & CMOD_NOAUTOCMD) && cmod->cmod_save_ei == NULL) {
     // Set 'eventignore' to "all".
     // First save the existing option value for restoring it later.
-    cmod->cmod_save_ei = vim_strsave(p_ei);
-    set_string_option_direct("ei", -1, (char_u *)"all", OPT_FREE, SID_NONE);
+    cmod->cmod_save_ei = (char *)vim_strsave(p_ei);
+    set_string_option_direct("ei", -1, "all", OPT_FREE, SID_NONE);
   }
 }
 
@@ -2688,7 +2688,7 @@ static void undo_cmdmod(cmdmod_T *cmod)
 
   if (cmod->cmod_save_ei != NULL) {
     // Restore 'eventignore' to the value before ":noautocmd".
-    set_string_option_direct("ei", -1, (char_u *)cmod->cmod_save_ei, OPT_FREE, SID_NONE);
+    set_string_option_direct("ei", -1, cmod->cmod_save_ei, OPT_FREE, SID_NONE);
     free_string_option((char_u *)cmod->cmod_save_ei);
     cmod->cmod_save_ei = NULL;
   }
@@ -5804,7 +5804,7 @@ static void uc_list(char *name, size_t name_len)
       } while (len < 25 - over);
 
       IObuff[len] = '\0';
-      msg_outtrans(IObuff);
+      msg_outtrans((char *)IObuff);
 
       msg_outtrans_special(cmd->uc_rep, false,
                            name_len == 0 ? Columns - 47 : 0);
@@ -7574,7 +7574,7 @@ static void ex_recover(exarg_T *eap)
                      | CCGD_EXCMD)
 
       && (*eap->arg == NUL
-          || setfname(curbuf, (char_u *)eap->arg, NULL, true) == OK)) {
+          || setfname(curbuf, eap->arg, NULL, true) == OK)) {
     ml_recover(true);
   }
   recoverymode = false;
@@ -7762,9 +7762,9 @@ static void ex_tabs(exarg_T *eap)
       if (buf_spname(wp->w_buffer) != NULL) {
         STRLCPY(IObuff, buf_spname(wp->w_buffer), IOSIZE);
       } else {
-        home_replace(wp->w_buffer, (char_u *)wp->w_buffer->b_fname, IObuff, IOSIZE, true);
+        home_replace(wp->w_buffer, wp->w_buffer->b_fname, (char *)IObuff, IOSIZE, true);
       }
-      msg_outtrans(IObuff);
+      msg_outtrans((char *)IObuff);
       ui_flush();                  // output one line at a time
       os_breakcheck();
     }
@@ -9646,7 +9646,7 @@ static char *arg_all(void)
   for (;;) {
     len = 0;
     for (idx = 0; idx < ARGCOUNT; idx++) {
-      p = (char *)alist_name(&ARGLIST[idx]);
+      p = alist_name(&ARGLIST[idx]);
       if (p == NULL) {
         continue;
       }
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index 420f3f73af..93758b9ec9 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -952,8 +952,7 @@ static uint8_t *command_line_enter(int firstc, long count, int indent, bool init
     need_wait_return = false;
   }
 
-  set_string_option_direct("icm", -1, s->save_p_icm, OPT_FREE,
-                           SID_NONE);
+  set_string_option_direct("icm", -1, (char *)s->save_p_icm, OPT_FREE, SID_NONE);
   State = s->save_State;
   if (cmdpreview != save_cmdpreview) {
     cmdpreview = save_cmdpreview;  // restore preview state
@@ -2751,7 +2750,7 @@ static int cmdline_charsize(int idx)
   if (cmdline_star > 0) {           // showing '*', always 1 position
     return 1;
   }
-  return ptr2cells(ccline.cmdbuff + idx);
+  return ptr2cells((char *)ccline.cmdbuff + idx);
 }
 
 /// Compute the offset of the cursor on the command line for the prompt and
@@ -3554,7 +3553,7 @@ void put_on_cmdline(char_u *str, int len, int redraw)
     }
     if (i != 0) {
       // Also backup the cursor position.
-      i = ptr2cells(ccline.cmdbuff + ccline.cmdpos);
+      i = ptr2cells((char *)ccline.cmdbuff + ccline.cmdpos);
       ccline.cmdspos -= i;
       msg_col -= i;
       if (msg_col < 0) {
@@ -4551,10 +4550,10 @@ static int showmatches(expand_T *xp, int wildmenu)
       if (!showtail && (xp->xp_context == EXPAND_FILES
                         || xp->xp_context == EXPAND_SHELLCMD
                         || xp->xp_context == EXPAND_BUFFERS)) {
-        home_replace(NULL, files_found[i], NameBuff, MAXPATHL, TRUE);
-        j = vim_strsize(NameBuff);
+        home_replace(NULL, (char *)files_found[i], (char *)NameBuff, MAXPATHL, true);
+        j = vim_strsize((char *)NameBuff);
       } else {
-        j = vim_strsize(L_SHOWFILE(i));
+        j = vim_strsize((char *)L_SHOWFILE(i));
       }
       if (j > maxlen) {
         maxlen = j;
@@ -4621,8 +4620,7 @@ static int showmatches(expand_T *xp, int wildmenu)
           if (showtail) {
             p = L_SHOWFILE(k);
           } else {
-            home_replace(NULL, files_found[k], NameBuff, MAXPATHL,
-                         TRUE);
+            home_replace(NULL, (char *)files_found[k], (char *)NameBuff, MAXPATHL, true);
             p = NameBuff;
           }
         } else {
@@ -6536,13 +6534,13 @@ void ex_history(exarg_T *eap)
           msg_putchar('\n');
           snprintf((char *)IObuff, IOSIZE, "%c%6d  ", i == idx ? '>' : ' ',
                    hist[i].hisnum);
-          if (vim_strsize(hist[i].hisstr) > Columns - 10) {
+          if (vim_strsize((char *)hist[i].hisstr) > Columns - 10) {
             trunc_string(hist[i].hisstr, IObuff + STRLEN(IObuff),
                          Columns - 10, IOSIZE - (int)STRLEN(IObuff));
           } else {
             STRCAT(IObuff, hist[i].hisstr);
           }
-          msg_outtrans(IObuff);
+          msg_outtrans((char *)IObuff);
           ui_flush();
         }
         if (i == idx) {
diff --git a/src/nvim/ex_session.c b/src/nvim/ex_session.c
index e60be80923..08c232ea69 100644
--- a/src/nvim/ex_session.c
+++ b/src/nvim/ex_session.c
@@ -215,7 +215,7 @@ static int ses_arglist(FILE *fd, char *cmd, garray_T *gap, int fullname, unsigne
   }
   for (int i = 0; i < gap->ga_len; i++) {
     // NULL file names are skipped (only happens when out of memory).
-    s = alist_name(&((aentry_T *)gap->ga_data)[i]);
+    s = (char_u *)alist_name(&((aentry_T *)gap->ga_data)[i]);
     if (s != NULL) {
       if (fullname) {
         buf = xmalloc(MAXPATHL);
diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index 4c1dd63b8f..f53f70dcda 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -1697,7 +1697,7 @@ failed:
     save_file_ff(curbuf);
     // If editing a new file: set 'fenc' for the current buffer.
     // Also for ":read ++edit file".
-    set_string_option_direct("fenc", -1, (char_u *)fenc, OPT_FREE | OPT_LOCAL, 0);
+    set_string_option_direct("fenc", -1, fenc, OPT_FREE | OPT_LOCAL, 0);
   }
   if (fenc_alloced) {
     xfree(fenc);
@@ -2057,7 +2057,7 @@ void set_forced_fenc(exarg_T *eap)
 {
   if (eap->force_enc != 0) {
     char_u *fenc = enc_canonize((char_u *)eap->cmd + eap->force_enc);
-    set_string_option_direct("fenc", -1, fenc, OPT_FREE|OPT_LOCAL, 0);
+    set_string_option_direct("fenc", -1, (char *)fenc, OPT_FREE|OPT_LOCAL, 0);
     xfree(fenc);
   }
 }
@@ -3765,7 +3765,7 @@ static int set_rw_fname(char_u *fname, char_u *sfname)
     return FAIL;
   }
 
-  if (setfname(curbuf, fname, sfname, false) == OK) {
+  if (setfname(curbuf, (char *)fname, (char *)sfname, false) == OK) {
     curbuf->b_flags |= BF_NOTEDITED;
   }
 
@@ -3805,8 +3805,7 @@ static void add_quoted_fname(char *const ret_buf, const size_t buf_len, const bu
     fname = "-stdin-";
   }
   ret_buf[0] = '"';
-  home_replace(buf, (const char_u *)fname, (char_u *)ret_buf + 1,
-               (int)buf_len - 4, true);
+  home_replace(buf, fname, ret_buf + 1, (int)buf_len - 4, true);
   xstrlcat(ret_buf, "\" ", buf_len);
 }
 
diff --git a/src/nvim/fold.c b/src/nvim/fold.c
index 93ad2a6926..3c3aaa1031 100644
--- a/src/nvim/fold.c
+++ b/src/nvim/fold.c
@@ -1813,7 +1813,7 @@ char_u *get_foldtext(win_T *wp, linenr_T lnum, linenr_T lnume, foldinfo_T foldin
           p += len - 1;
         } else if (*p == TAB) {
           *p = ' ';
-        } else if (ptr2cells(p) > 1) {
+        } else if (ptr2cells((char *)p) > 1) {
           break;
         }
       }
diff --git a/src/nvim/getchar.c b/src/nvim/getchar.c
index d11088ed6b..6fdc10ae0b 100644
--- a/src/nvim/getchar.c
+++ b/src/nvim/getchar.c
@@ -2501,7 +2501,7 @@ static int vgetorpeek(bool advance)
               && State != MODE_HITRETURN) {
             // this looks nice when typing a dead character map
             if (State & MODE_INSERT
-                && ptr2cells(typebuf.tb_buf + typebuf.tb_off + typebuf.tb_len - 1) == 1) {
+                && ptr2cells((char *)typebuf.tb_buf + typebuf.tb_off + typebuf.tb_len - 1) == 1) {
               edit_putchar(typebuf.tb_buf[typebuf.tb_off + typebuf.tb_len - 1], false);
               setcursor();  // put cursor back where it belongs
               c1 = 1;
@@ -2524,9 +2524,9 @@ static int vgetorpeek(bool advance)
 
           // this looks nice when typing a dead character map
           if ((State & MODE_CMDLINE) && cmdline_star == 0) {
-            char_u *p = typebuf.tb_buf + typebuf.tb_off + typebuf.tb_len - 1;
-            if (ptr2cells(p) == 1 && *p < 128) {
-              putcmdline((char)(*p), false);
+            char *p = (char *)typebuf.tb_buf + typebuf.tb_off + typebuf.tb_len - 1;
+            if (ptr2cells(p) == 1 && (uint8_t)(*p) < 128) {
+              putcmdline(*p, false);
               c1 = 1;
             }
           }
diff --git a/src/nvim/hardcopy.c b/src/nvim/hardcopy.c
index aeccac060a..1dd0a5f3e8 100644
--- a/src/nvim/hardcopy.c
+++ b/src/nvim/hardcopy.c
@@ -658,7 +658,7 @@ void ex_hardcopy(exarg_T *eap)
    * PS.)
    */
   if (mch_print_init(&settings,
-                     curbuf->b_fname == NULL ? buf_spname(curbuf) : curbuf->b_sfname ==
+                     curbuf->b_fname == NULL ? (char_u *)buf_spname(curbuf) : curbuf->b_sfname ==
                      NULL ? (char_u *)curbuf->b_fname : curbuf->b_sfname, eap->forceit) == FAIL) {
     return;
   }
diff --git a/src/nvim/highlight_group.c b/src/nvim/highlight_group.c
index ac7f6c4317..e5d9a9269c 100644
--- a/src/nvim/highlight_group.c
+++ b/src/nvim/highlight_group.c
@@ -811,7 +811,7 @@ void do_highlight(const char *line, const bool forceit, const bool init)
 
   // ":highlight {group-name}": list highlighting for one group.
   if (!doclear && !dolink && ends_excmd((uint8_t)(*linep))) {
-    id = syn_name2id_len((const char_u *)line, (size_t)(name_end - line));
+    id = syn_name2id_len(line, (size_t)(name_end - line));
     if (id == 0) {
       semsg(_("E411: highlight group not found: %s"), line);
     } else {
@@ -1389,7 +1389,7 @@ static void highlight_list_one(const int id)
     didh = true;
     msg_puts_attr("links to", HL_ATTR(HLF_D));
     msg_putchar(' ');
-    msg_outtrans(hl_table[hl_table[id - 1].sg_link - 1].sg_name);
+    msg_outtrans((char *)hl_table[hl_table[id - 1].sg_link - 1].sg_name);
   }
 
   if (!didh) {
@@ -1450,14 +1450,14 @@ static bool highlight_list_arg(const int id, bool didh, const int type, int iarg
       }
     }
 
-    (void)syn_list_header(didh, vim_strsize((char_u *)ts) + (int)STRLEN(name) + 1, id, false);
+    (void)syn_list_header(didh, vim_strsize((char *)ts) + (int)STRLEN(name) + 1, id, false);
     didh = true;
     if (!got_int) {
       if (*name != NUL) {
         msg_puts_attr(name, HL_ATTR(HLF_D));
         msg_puts_attr("=", HL_ATTR(HLF_D));
       }
-      msg_outtrans((char_u *)ts);
+      msg_outtrans((char *)ts);
     }
   }
   return didh;
@@ -1581,7 +1581,7 @@ bool syn_list_header(const bool did_header, const int outlen, const int id, bool
     if (got_int) {
       return true;
     }
-    msg_outtrans(hl_table[id - 1].sg_name);
+    msg_outtrans((char *)hl_table[id - 1].sg_name);
     name_col = msg_col;
     endcol = 15;
   } else if ((ui_has(kUIMessages) || msg_silent) && !force_newline) {
@@ -1650,14 +1650,14 @@ static void set_hl_attr(int idx)
 int syn_name2id(const char *name)
   FUNC_ATTR_NONNULL_ALL
 {
-  return syn_name2id_len((char_u *)name, STRLEN(name));
+  return syn_name2id_len(name, STRLEN(name));
 }
 
 /// Lookup a highlight group name and return its ID.
 ///
 /// @param highlight name e.g. 'Cursor', 'Normal'
 /// @return the highlight id, else 0 if \p name does not exist
-int syn_name2id_len(const char_u *name, size_t len)
+int syn_name2id_len(const char *name, size_t len)
   FUNC_ATTR_NONNULL_ALL
 {
   char name_u[MAX_SYN_NAME + 1];
@@ -1719,7 +1719,7 @@ int syn_check_group(const char *name, size_t len)
     emsg(_(e_highlight_group_name_too_long));
     return 0;
   }
-  int id = syn_name2id_len((char_u *)name, len);
+  int id = syn_name2id_len(name, len);
   if (id == 0) {  // doesn't exist yet
     return syn_add_group(name, len);
   }
@@ -1735,7 +1735,7 @@ static int syn_add_group(const char *name, size_t len)
 {
   // Check that the name is ASCII letters, digits and underscore.
   for (size_t i = 0; i < len; i++) {
-    int c = (int8_t)name[i];
+    int c = (uint8_t)name[i];
     if (!vim_isprintc(c)) {
       emsg(_("E669: Unprintable character in group name"));
       return 0;
diff --git a/src/nvim/if_cscope.c b/src/nvim/if_cscope.c
index f01f4fc771..8d08c2fc19 100644
--- a/src/nvim/if_cscope.c
+++ b/src/nvim/if_cscope.c
@@ -1078,7 +1078,7 @@ static int cs_help(exarg_T *eap)
   (void)msg_puts(_("cscope commands:\n"));
   while (cmdp->name != NULL) {
     char *help = _(cmdp->help);
-    int space_cnt = 30 - vim_strsize((char_u *)help);
+    int space_cnt = 30 - vim_strsize(help);
 
     // Use %*s rather than %30s to ensure proper alignment in utf-8
     if (space_cnt < 0) {
diff --git a/src/nvim/indent.c b/src/nvim/indent.c
index d71b3adb5c..8a5b4cbf0f 100644
--- a/src/nvim/indent.c
+++ b/src/nvim/indent.c
@@ -75,7 +75,7 @@ int get_indent_str(const char_u *ptr, int ts, bool list)
       } else {
         // In list mode, when tab is not set, count screen char width
         // for Tab, displays: ^I
-        count += ptr2cells(ptr);
+        count += ptr2cells((char *)ptr);
       }
     } else if (*ptr == ' ') {
       // Count a space for one.
@@ -101,7 +101,7 @@ int get_indent_str_vtab(const char_u *ptr, long ts, long *vts, bool list)
       } else {
         // In list mode, when tab is not set, count screen char width
         // for Tab, displays: ^I
-        count += ptr2cells(ptr);
+        count += ptr2cells((char *)ptr);
       }
     } else if (*ptr == ' ') {
       count++;  // count a space for one
@@ -481,7 +481,7 @@ int get_breakindent_win(win_T *wp, char_u *line)
 
   // indent minus the length of the showbreak string
   if (wp->w_briopt_sbr) {
-    bri -= vim_strsize(get_showbreak_value(wp));
+    bri -= vim_strsize((char *)get_showbreak_value(wp));
   }
 
   // never indent past left window margin
diff --git a/src/nvim/indent_c.c b/src/nvim/indent_c.c
index 29d3c5f95b..cb807dec24 100644
--- a/src/nvim/indent_c.c
+++ b/src/nvim/indent_c.c
@@ -2049,9 +2049,9 @@ int get_c_indent(void)
   if (!cin_iscomment(theline) && comment_pos != NULL) {  // XXX
     int lead_start_len = 2;
     int lead_middle_len = 1;
-    char_u lead_start[COM_MAX_LEN];             // start-comment string
-    char_u lead_middle[COM_MAX_LEN];            // middle-comment string
-    char_u lead_end[COM_MAX_LEN];               // end-comment string
+    char lead_start[COM_MAX_LEN];             // start-comment string
+    char lead_middle[COM_MAX_LEN];            // middle-comment string
+    char lead_end[COM_MAX_LEN];               // end-comment string
     char_u *p;
     int start_align = 0;
     int start_off = 0;
@@ -2084,7 +2084,7 @@ int get_c_indent(void)
       if (*p == ':') {
         p++;
       }
-      (void)copy_option_part(&p, lead_end, COM_MAX_LEN, ",");
+      (void)copy_option_part(&p, (char_u *)lead_end, COM_MAX_LEN, ",");
       if (what == COM_START) {
         STRCPY(lead_start, lead_end);
         lead_start_len = (int)STRLEN(lead_start);
@@ -2120,8 +2120,7 @@ int get_c_indent(void)
           if (start_off != 0) {
             amount += start_off;
           } else if (start_align == COM_RIGHT) {
-            amount += vim_strsize(lead_start)
-                      - vim_strsize(lead_middle);
+            amount += vim_strsize(lead_start) - vim_strsize(lead_middle);
           }
           break;
         }
diff --git a/src/nvim/main.c b/src/nvim/main.c
index 124248508e..2b5a5a9033 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -1357,9 +1357,8 @@ scripterror:
       char_u *p = vim_strsave((char_u *)argv[0]);
 
       if (parmp->diff_mode && os_isdir(p) && GARGCOUNT > 0
-          && !os_isdir(alist_name(&GARGLIST[0]))) {
-        char_u *r = (char_u *)concat_fnames((char *)p,
-                                            path_tail((char *)alist_name(&GARGLIST[0])), true);
+          && !os_isdir((char_u *)alist_name(&GARGLIST[0]))) {
+        char_u *r = (char_u *)concat_fnames((char *)p, path_tail(alist_name(&GARGLIST[0])), true);
         xfree(p);
         p = r;
       }
@@ -1477,7 +1476,7 @@ static void init_path(const char *exename)
 /// Get filename from command line, if any.
 static char_u *get_fname(mparm_T *parmp, char_u *cwd)
 {
-  return alist_name(&GARGLIST[0]);
+  return (char_u *)alist_name(&GARGLIST[0]);
 }
 
 /*
@@ -1502,7 +1501,7 @@ static void handle_quickfix(mparm_T *paramp)
 {
   if (paramp->edit_type == EDIT_QF) {
     if (paramp->use_ef != NULL) {
-      set_string_option_direct("ef", -1, (char_u *)paramp->use_ef, OPT_FREE, SID_CARG);
+      set_string_option_direct("ef", -1, paramp->use_ef, OPT_FREE, SID_CARG);
     }
     vim_snprintf((char *)IObuff, IOSIZE, "cfile %s", p_ef);
     if (qf_init(NULL, (char *)p_ef, p_efm, true, (char *)IObuff, (char *)p_menc) < 0) {
@@ -1743,7 +1742,7 @@ static void edit_buffers(mparm_T *parmp, char_u *cwd)
       // at the ATTENTION prompt close the window.
       swap_exists_did_quit = false;
       (void)do_ecmd(0, arg_idx < GARGCOUNT
-                    ? (char *)alist_name(&GARGLIST[arg_idx])
+                    ? alist_name(&GARGLIST[arg_idx])
                     : NULL, NULL, NULL, ECMD_LASTL, ECMD_HIDE, curwin);
       if (swap_exists_did_quit) {
         // abort or quit selected
@@ -1946,9 +1945,7 @@ static bool do_user_initialization(void)
   if (do_source((char *)user_vimrc, true, DOSO_VIMRC) != FAIL) {
     do_exrc = p_exrc;
     if (do_exrc) {
-      do_exrc = (path_full_compare((char_u *)VIMRC_FILE, user_vimrc,
-                                   false, true)
-                 != kEqualFiles);
+      do_exrc = (path_full_compare(VIMRC_FILE, (char *)user_vimrc, false, true) != kEqualFiles);
     }
     xfree(user_vimrc);
     return do_exrc;
@@ -1974,8 +1971,7 @@ static bool do_user_initialization(void)
       if (do_source(vimrc, true, DOSO_VIMRC) != FAIL) {
         do_exrc = p_exrc;
         if (do_exrc) {
-          do_exrc = (path_full_compare((char_u *)VIMRC_FILE, (char_u *)vimrc,
-                                       false, true) != kEqualFiles);
+          do_exrc = (path_full_compare(VIMRC_FILE, vimrc, false, true) != kEqualFiles);
         }
         xfree(vimrc);
         xfree(config_dirs);
diff --git a/src/nvim/mapping.c b/src/nvim/mapping.c
index d0ecf7549a..d4f7450af4 100644
--- a/src/nvim/mapping.c
+++ b/src/nvim/mapping.c
@@ -2324,7 +2324,7 @@ void ex_map(exarg_T *eap)
   // print the mappings for security reasons.
   if (secure) {
     secure = 2;
-    msg_outtrans((char_u *)eap->cmd);
+    msg_outtrans(eap->cmd);
     msg_putchar('\n');
   }
   do_exmap(eap, false);
diff --git a/src/nvim/mark.c b/src/nvim/mark.c
index 8d1a917600..a0fed19a98 100644
--- a/src/nvim/mark.c
+++ b/src/nvim/mark.c
@@ -637,7 +637,7 @@ static char_u *mark_line(pos_T *mp, int lead_len)
   // Truncate the line to fit it in the window
   len = 0;
   for (p = s; *p != NUL; MB_PTR_ADV(p)) {
-    len += ptr2cells(p);
+    len += ptr2cells((char *)p);
     if (len >= Columns - lead_len) {
       break;
     }
@@ -733,7 +733,7 @@ static void show_one_mark(int c, char_u *arg, pos_T *p, char_u *name_arg, int cu
       msg_putchar('\n');
       if (!got_int) {
         snprintf((char *)IObuff, IOSIZE, " %c %6" PRIdLINENR " %4d ", c, p->lnum, p->col);
-        msg_outtrans(IObuff);
+        msg_outtrans((char *)IObuff);
         if (name != NULL) {
           msg_outtrans_attr(name, current ? HL_ATTR(HLF_D) : 0);
         }
@@ -864,7 +864,7 @@ void ex_jumps(exarg_T *eap)
                i == curwin->w_jumplistidx ? '>' : ' ',
                i > curwin->w_jumplistidx ? i - curwin->w_jumplistidx : curwin->w_jumplistidx - i,
                curwin->w_jumplist[i].fmark.mark.lnum, curwin->w_jumplist[i].fmark.mark.col);
-      msg_outtrans(IObuff);
+      msg_outtrans((char *)IObuff);
       msg_outtrans_attr(name,
                         curwin->w_jumplist[i].fmark.fnum == curbuf->b_fnum
                         ? HL_ATTR(HLF_D) : 0);
@@ -908,7 +908,7 @@ void ex_changes(exarg_T *eap)
                                           : curwin->w_changelistidx - i,
               (long)curbuf->b_changelist[i].mark.lnum,
               curbuf->b_changelist[i].mark.col);
-      msg_outtrans(IObuff);
+      msg_outtrans((char *)IObuff);
       name = mark_line(&curbuf->b_changelist[i].mark, 17);
       msg_outtrans_attr(name, HL_ATTR(HLF_D));
       xfree(name);
@@ -1578,7 +1578,7 @@ void mark_mb_adjustpos(buf_T *buf, pos_T *lp)
     if (lp->coladd == 1
         && p[lp->col] != TAB
         && vim_isprintc(utf_ptr2char((char *)p + lp->col))
-        && ptr2cells(p + lp->col) > 1) {
+        && ptr2cells((char *)p + lp->col) > 1) {
       lp->coladd = 0;
     }
   }
diff --git a/src/nvim/mbyte.c b/src/nvim/mbyte.c
index 24d079ea2c..1032986a02 100644
--- a/src/nvim/mbyte.c
+++ b/src/nvim/mbyte.c
@@ -2012,7 +2012,7 @@ void mb_check_adjust_col(void *win_)
 
   // Column 0 is always valid.
   if (oldcol != 0) {
-    char_u *p = ml_get_buf(win->w_buffer, win->w_cursor.lnum, false);
+    char *p = (char *)ml_get_buf(win->w_buffer, win->w_cursor.lnum, false);
     colnr_T len = (colnr_T)STRLEN(p);
 
     // Empty line or invalid column?
@@ -2024,13 +2024,13 @@ void mb_check_adjust_col(void *win_)
         win->w_cursor.col = len - 1;
       }
       // Move the cursor to the head byte.
-      win->w_cursor.col -= utf_head_off(p, p + win->w_cursor.col);
+      win->w_cursor.col -= utf_head_off((char_u *)p, (char_u *)p + win->w_cursor.col);
     }
 
     // Reset `coladd` when the cursor would be on the right half of a
     // double-wide character.
     if (win->w_cursor.coladd == 1 && p[win->w_cursor.col] != TAB
-        && vim_isprintc(utf_ptr2char((char *)p + win->w_cursor.col))
+        && vim_isprintc(utf_ptr2char(p + win->w_cursor.col))
         && ptr2cells(p + win->w_cursor.col) > 1) {
       win->w_cursor.coladd = 0;
     }
diff --git a/src/nvim/memline.c b/src/nvim/memline.c
index 21b0ab89d7..9da5aa54c5 100644
--- a/src/nvim/memline.c
+++ b/src/nvim/memline.c
@@ -531,7 +531,7 @@ void ml_open_file(buf_T *buf)
     need_wait_return = true;  // call wait_return later
     no_wait_return++;
     (void)semsg(_("E303: Unable to open swap file for \"%s\", recovery impossible"),
-                buf_spname(buf) != NULL ? buf_spname(buf) : (char_u *)buf->b_fname);
+                buf_spname(buf) != NULL ? buf_spname(buf) : buf->b_fname);
     no_wait_return--;
   }
 
@@ -665,8 +665,8 @@ static void set_b0_fname(ZERO_BL *b0p, buf_T *buf)
      * First replace home dir path with "~/" with home_replace().
      * Then insert the user name to get "~user/".
      */
-    home_replace(NULL, buf->b_ffname, b0p->b0_fname,
-                 B0_FNAME_SIZE_CRYPT, TRUE);
+    home_replace(NULL, (char *)buf->b_ffname, (char *)b0p->b0_fname,
+                 B0_FNAME_SIZE_CRYPT, true);
     if (b0p->b0_fname[0] == '~') {
       // If there is no user name or it is too long, don't use "~/"
       int retval = os_get_user_name(uname, B0_UNAME_SIZE);
@@ -933,18 +933,18 @@ void ml_recover(bool checkext)
    */
   if (directly) {
     expand_env(b0p->b0_fname, NameBuff, MAXPATHL);
-    if (setfname(curbuf, NameBuff, NULL, true) == FAIL) {
+    if (setfname(curbuf, (char *)NameBuff, NULL, true) == FAIL) {
       goto theend;
     }
   }
 
-  home_replace(NULL, mfp->mf_fname, NameBuff, MAXPATHL, TRUE);
+  home_replace(NULL, (char *)mfp->mf_fname, (char *)NameBuff, MAXPATHL, true);
   smsg(_("Using swap file \"%s\""), NameBuff);
 
   if (buf_spname(curbuf) != NULL) {
     STRLCPY(NameBuff, buf_spname(curbuf), MAXPATHL);
   } else {
-    home_replace(NULL, curbuf->b_ffname, NameBuff, MAXPATHL, TRUE);
+    home_replace(NULL, (char *)curbuf->b_ffname, (char *)NameBuff, MAXPATHL, true);
   }
   smsg(_("Original file \"%s\""), NameBuff);
   msg_putchar('\n');
@@ -1377,7 +1377,7 @@ int recover_names(char_u *fname, int list, int nr, char_u **fname_out)
       for (int i = 0; i < num_files; i++) {
         // Do not expand wildcards, on Windows would try to expand
         // "%tmp%" in "%tmp%file"
-        if (path_full_compare(p, files[i], true, false) & kEqualFiles) {
+        if (path_full_compare((char *)p, (char *)files[i], true, false) & kEqualFiles) {
           // Remove the name from files[i].  Move further entries
           // down.  When the array becomes empty free it here, since
           // FreeWild() won't be called below.
@@ -1520,7 +1520,7 @@ static time_t swapfile_info(char_u *fname)
     // print name of owner of the file
     if (os_get_uname(file_info.stat.st_uid, uname, B0_UNAME_SIZE) == OK) {
       msg_puts(_("          owned by: "));
-      msg_outtrans((char_u *)uname);
+      msg_outtrans(uname);
       msg_puts(_("   dated: "));
     } else
 #endif
@@ -1547,7 +1547,7 @@ static time_t swapfile_info(char_u *fname)
         if (b0.b0_fname[0] == NUL) {
           msg_puts(_("[No Name]"));
         } else {
-          msg_outtrans(b0.b0_fname);
+          msg_outtrans((char *)b0.b0_fname);
         }
 
         msg_puts(_("\n          modified: "));
@@ -1555,7 +1555,7 @@ static time_t swapfile_info(char_u *fname)
 
         if (*(b0.b0_uname) != NUL) {
           msg_puts(_("\n         user name: "));
-          msg_outtrans(b0.b0_uname);
+          msg_outtrans((char *)b0.b0_uname);
         }
 
         if (*(b0.b0_hname) != NUL) {
@@ -1564,7 +1564,7 @@ static time_t swapfile_info(char_u *fname)
           } else {
             msg_puts(_("\n         host name: "));
           }
-          msg_outtrans(b0.b0_hname);
+          msg_outtrans((char *)b0.b0_hname);
         }
 
         if (char_to_long(b0.b0_pid) != 0L) {
@@ -3317,7 +3317,7 @@ static void attention_message(buf_T *buf, char_u *fname)
   msg_puts("\"\n");
   const time_t swap_mtime = swapfile_info(fname);
   msg_puts(_("While opening file \""));
-  msg_outtrans((char_u *)buf->b_fname);
+  msg_outtrans(buf->b_fname);
   msg_puts("\"\n");
   FileInfo file_info;
   if (!os_fileinfo(buf->b_fname, &file_info)) {
@@ -3339,10 +3339,10 @@ static void attention_message(buf_T *buf, char_u *fname)
              "  Quit, or continue with caution.\n"));
   msg_puts(_("(2) An edit session for this file crashed.\n"));
   msg_puts(_("    If this is the case, use \":recover\" or \"vim -r "));
-  msg_outtrans((char_u *)buf->b_fname);
+  msg_outtrans(buf->b_fname);
   msg_puts(_("\"\n    to recover the changes (see \":help recovery\").\n"));
   msg_puts(_("    If you did this already, delete the swap file \""));
-  msg_outtrans(fname);
+  msg_outtrans((char *)fname);
   msg_puts(_("\"\n    to avoid this message.\n"));
   cmdline_row = msg_row;
   --no_wait_return;
@@ -3552,8 +3552,7 @@ static char *findswapname(buf_T *buf, char **dirp, char *old_fname, bool *found_
 
             char *const name = xmalloc(name_len);
             memcpy(name, sw_msg_1, sw_msg_1_len + 1);
-            home_replace(NULL, (char_u *)fname, (char_u *)&name[sw_msg_1_len],
-                         fname_len, true);
+            home_replace(NULL, fname, &name[sw_msg_1_len], fname_len, true);
             xstrlcat(name, sw_msg_2, name_len);
             choice = do_dialog(VIM_WARNING, (char_u *)_("VIM - ATTENTION"),
                                (char_u *)name,
diff --git a/src/nvim/message.c b/src/nvim/message.c
index 82e299e8e9..733b4808fe 100644
--- a/src/nvim/message.c
+++ b/src/nvim/message.c
@@ -348,7 +348,7 @@ 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 *)s) < (Rows - cmdline_row - 1) * Columns + sc_col) {
     set_keep_msg((char *)s, 0);
   }
 
@@ -374,7 +374,7 @@ char_u *msg_strtrunc(char_u *s, int force)
   if ((!msg_scroll && !need_wait_return && shortmess(SHM_TRUNCALL)
        && !exmode_active && msg_silent == 0 && !ui_has(kUIMessages))
       || force) {
-    len = vim_strsize(s);
+    len = vim_strsize((char *)s);
     if (msg_scrolled != 0) {
       // Use all the columns.
       room = (Rows - msg_row) * Columns - 1;
@@ -423,7 +423,7 @@ void trunc_string(char_u *s, char_u *buf, int room_in, int buflen)
       buf[e] = NUL;
       return;
     }
-    n = ptr2cells(s + e);
+    n = ptr2cells((char *)s + e);
     if (len + n > half) {
       break;
     }
@@ -443,7 +443,7 @@ void trunc_string(char_u *s, char_u *buf, int room_in, int buflen)
     do {
       half = half - utf_head_off(s, s + half - 1) - 1;
     } while (half > 0 && utf_iscomposing(utf_ptr2char((char *)s + half)));
-    n = ptr2cells(s + half);
+    n = ptr2cells((char *)s + half);
     if (len + n > room || half == 0) {
       break;
     }
@@ -892,7 +892,7 @@ char_u *msg_may_trunc(bool force, char_u *s)
   room = (Rows - cmdline_row - 1) * Columns + sc_col - 1;
   if ((force || (shortmess(SHM_TRUNC) && !exmode_active))
       && (int)STRLEN(s) - room > 0) {
-    int size = vim_strsize(s);
+    int size = vim_strsize((char *)s);
 
     // There may be room anyway when there are multibyte chars.
     if (size <= room) {
@@ -1275,7 +1275,7 @@ void wait_return(int redraw)
   emsg_on_display = false;      // can delete error message now
   lines_left = -1;              // reset lines_left at next msg_start()
   reset_last_sourcing();
-  if (keep_msg != NULL && vim_strsize(keep_msg) >=
+  if (keep_msg != NULL && vim_strsize((char *)keep_msg) >=
       (Rows - cmdline_row - 1) * Columns + sc_col) {
     XFREE_CLEAR(keep_msg);          // don't redisplay message, it's too long
   }
@@ -1489,9 +1489,9 @@ static void msg_home_replace_attr(char_u *fname, int attr)
 /// Use attributes 'attr'.
 ///
 /// @return  the number of characters it takes on the screen.
-int msg_outtrans(char_u *str)
+int msg_outtrans(char *str)
 {
-  return msg_outtrans_attr(str, 0);
+  return msg_outtrans_attr((char_u *)str, 0);
 }
 
 int msg_outtrans_attr(const char_u *str, int attr)
@@ -1654,7 +1654,7 @@ int msg_outtrans_special(const char_u *strstart, bool from, int maxlen)
       // single-byte character or illegal byte
       text = (char *)transchar_byte((uint8_t)text[0]);
     }
-    const int len = vim_strsize((char_u *)text);
+    const int len = vim_strsize((char *)text);
     if (maxlen > 0 && retval + len >= maxlen) {
       break;
     }
@@ -3027,7 +3027,7 @@ void msg_moremsg(int full)
   if (full) {
     grid_puts(&msg_grid_adj, (char_u *)
               _(" SPACE/d/j: screen/page/line down, b/u/k: up, q: quit "),
-              Rows - 1, vim_strsize(s), attr);
+              Rows - 1, vim_strsize((char *)s), attr);
   }
 }
 
@@ -3376,7 +3376,8 @@ int verbose_open(void)
 
 /// Give a warning message (for searching).
 /// Use 'w' highlighting and may repeat the message after redrawing
-void give_warning(char_u *message, bool hl) FUNC_ATTR_NONNULL_ARG(1)
+void give_warning(char *message, bool hl)
+  FUNC_ATTR_NONNULL_ARG(1)
 {
   // Don't do this for ":silent".
   if (msg_silent != 0) {
@@ -3386,7 +3387,7 @@ void give_warning(char_u *message, bool hl) FUNC_ATTR_NONNULL_ARG(1)
   // Don't want a hit-enter prompt here.
   no_wait_return++;
 
-  set_vim_var_string(VV_WARNINGMSG, (char *)message, -1);
+  set_vim_var_string(VV_WARNINGMSG, message, -1);
   XFREE_CLEAR(keep_msg);
   if (hl) {
     keep_msg_attr = HL_ATTR(HLF_W);
@@ -3399,7 +3400,7 @@ void give_warning(char_u *message, bool hl) FUNC_ATTR_NONNULL_ARG(1)
   }
 
   if (msg_attr((const char *)message, keep_msg_attr) && msg_scrolled == 0) {
-    set_keep_msg((char *)message, keep_msg_attr);
+    set_keep_msg(message, keep_msg_attr);
   }
   msg_didout = false;  // Overwrite this message.
   msg_nowait = true;   // Don't wait for this message.
@@ -3411,7 +3412,7 @@ void give_warning(char_u *message, bool hl) FUNC_ATTR_NONNULL_ARG(1)
 void give_warning2(char_u *const message, char_u *const a1, bool hl)
 {
   vim_snprintf((char *)IObuff, IOSIZE, (char *)message, a1);
-  give_warning(IObuff, hl);
+  give_warning((char *)IObuff, hl);
 }
 
 /// Advance msg cursor to column "col".
diff --git a/src/nvim/move.c b/src/nvim/move.c
index cc811fca18..99ca5060cd 100644
--- a/src/nvim/move.c
+++ b/src/nvim/move.c
@@ -802,7 +802,7 @@ void curs_columns(win_T *wp, int may_scroll)
       // column
       char *const sbr = (char *)get_showbreak_value(wp);
       if (*sbr && *get_cursor_pos_ptr() == NUL
-          && wp->w_wcol == vim_strsize((char_u *)sbr)) {
+          && wp->w_wcol == vim_strsize(sbr)) {
         wp->w_wcol = 0;
       }
     }
diff --git a/src/nvim/normal.c b/src/nvim/normal.c
index 5ed1a61b54..9637fe85e2 100644
--- a/src/nvim/normal.c
+++ b/src/nvim/normal.c
@@ -3287,7 +3287,7 @@ static bool nv_screengo(oparg_T *oap, int dir, long dist)
     validate_virtcol();
     colnr_T virtcol = curwin->w_virtcol;
     if (virtcol > (colnr_T)width1 && *get_showbreak_value(curwin) != NUL) {
-      virtcol -= vim_strsize(get_showbreak_value(curwin));
+      virtcol -= vim_strsize((char *)get_showbreak_value(curwin));
     }
 
     int c = utf_ptr2char((char *)get_cursor_pos_ptr());
diff --git a/src/nvim/ops.c b/src/nvim/ops.c
index 20bbc5b440..fcff2517ab 100644
--- a/src/nvim/ops.c
+++ b/src/nvim/ops.c
@@ -3847,7 +3847,7 @@ void ex_display(exarg_T *eap)
             n -= 2;
           }
           for (p = (char_u *)yb->y_array[j];
-               *p != NUL && (n -= ptr2cells(p)) >= 0; p++) {  // -V1019
+               *p != NUL && (n -= ptr2cells((char *)p)) >= 0; p++) {  // -V1019
             clen = utfc_ptr2len((char *)p);
             msg_outtrans_len(p, clen);
             p += clen - 1;
@@ -3925,7 +3925,7 @@ static void dis_msg(const char_u *p, bool skip_esc)
   n = Columns - 6;
   while (*p != NUL
          && !(*p == ESC && skip_esc && *(p + 1) == NUL)
-         && (n -= ptr2cells(p)) >= 0) {
+         && (n -= ptr2cells((char *)p)) >= 0) {
     if ((l = utfc_ptr2len((char *)p)) > 1) {
       msg_outtrans_len(p, l);
       p += l;
diff --git a/src/nvim/option.c b/src/nvim/option.c
index 8cd9b5aead..09a597f7e2 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -621,7 +621,7 @@ static void set_option_default(int opt_idx, int opt_flags)
       // freeing and allocating the value.
       if (options[opt_idx].indir != PV_NONE) {
         set_string_option_direct(NULL, opt_idx,
-                                 options[opt_idx].def_val, opt_flags, 0);
+                                 (char *)options[opt_idx].def_val, opt_flags, 0);
       } else {
         if ((opt_flags & OPT_FREE) && (flags & P_ALLOCED)) {
           free_string_option(*(char_u **)(varp));
@@ -944,7 +944,7 @@ void ex_set(exarg_T *eap)
   if (eap->forceit) {
     flags |= OPT_ONECOLUMN;
   }
-  (void)do_set((char_u *)eap->arg, flags);
+  (void)do_set(eap->arg, flags);
 }
 
 /// Parse 'arg' for option settings.
@@ -962,7 +962,7 @@ void ex_set(exarg_T *eap)
 /// @param arg  option string (may be written to!)
 ///
 /// @return  FAIL if an error is detected, OK otherwise
-int do_set(char_u *arg, int opt_flags)
+int do_set(char *arg, int opt_flags)
 {
   int opt_idx;
   char *errmsg;
@@ -990,7 +990,7 @@ int do_set(char_u *arg, int opt_flags)
 
   while (*arg != NUL) {         // loop to process all options
     errmsg = NULL;
-    startarg = arg;             // remember for error message
+    startarg = (char_u *)arg;             // remember for error message
 
     if (STRNCMP(arg, "all", 3) == 0 && !isalpha(arg[3])
         && !(opt_flags & OPT_MODELINE)) {
@@ -1043,7 +1043,7 @@ int do_set(char_u *arg, int opt_flags)
         }
         len++;
         if (opt_idx == -1) {
-          key = find_key_option(arg + 1, true);
+          key = find_key_option((char_u *)arg + 1, true);
         }
       } else {
         len = 0;
@@ -1057,12 +1057,12 @@ int do_set(char_u *arg, int opt_flags)
         }
         opt_idx = findoption_len((const char *)arg, (size_t)len);
         if (opt_idx == -1) {
-          key = find_key_option(arg, false);
+          key = find_key_option((char_u *)arg, false);
         }
       }
 
       // remember character after option name
-      afterchar = arg[len];
+      afterchar = (uint8_t)arg[len];
 
       // skip white space, allow ":set ai  ?"
       while (ascii_iswhite(arg[len])) {
@@ -1084,7 +1084,7 @@ int do_set(char_u *arg, int opt_flags)
           len++;
         }
       }
-      nextchar = arg[len];
+      nextchar = (uint8_t)arg[len];
 
       if (opt_idx == -1 && key == 0) {          // found a mismatch: skip
         errmsg = N_("E518: Unknown option");
@@ -1282,14 +1282,14 @@ int do_set(char_u *arg, int opt_flags)
                            || *arg == '^'
                            || (*arg != NUL && (!arg[1] || ascii_iswhite(arg[1]))
                                && !ascii_isdigit(*arg)))) {
-              value = string_to_key(arg);
+              value = string_to_key((char_u *)arg);
               if (value == 0 && (long *)varp != &p_wcm) {
                 errmsg = e_invarg;
                 goto skip;
               }
             } else if (*arg == '-' || ascii_isdigit(*arg)) {
               // Allow negative, octal and hex numbers.
-              vim_str2nr(arg, NULL, &i, STR2NR_ALL, &value, NULL, 0, true);
+              vim_str2nr((char_u *)arg, NULL, &i, STR2NR_ALL, &value, NULL, 0, true);
               if (i == 0 || (arg[i] != NUL && !ascii_iswhite(arg[i]))) {
                 errmsg = N_("E521: Number required after =");
                 goto skip;
@@ -1391,8 +1391,8 @@ int do_set(char_u *arg, int opt_flags)
               if (varp == (char_u *)&p_kp
                   && (*arg == NUL || *arg == ' ')) {
                 STRCPY(errbuf, ":help");
-                save_arg = arg;
-                arg = (char_u *)errbuf;
+                save_arg = (char_u *)arg;
+                arg = errbuf;
               }
               /*
                * Convert 'backspace' number to string, for
@@ -1435,7 +1435,7 @@ int do_set(char_u *arg, int opt_flags)
               else if (varp == (char_u *)&p_ww
                        && ascii_isdigit(*arg)) {
                 *errbuf = NUL;
-                i = getdigits_int(&arg, true, 0);
+                i = getdigits_int((char_u **)&arg, true, 0);
                 if (i & 1) {
                   STRLCAT(errbuf, "b,", sizeof(errbuf));
                 }
@@ -1451,8 +1451,8 @@ int do_set(char_u *arg, int opt_flags)
                 if (i & 16) {
                   STRLCAT(errbuf, "[,],", sizeof(errbuf));
                 }
-                save_arg = arg;
-                arg = (char_u *)errbuf;
+                save_arg = (char_u *)arg;
+                arg = errbuf;
               }
               /*
                * Remove '>' before 'dir' and 'bdir', for
@@ -1498,14 +1498,14 @@ int do_set(char_u *arg, int opt_flags)
                     ) {
                   arg++;                        // remove backslash
                 }
-                i = utfc_ptr2len((char *)arg);
+                i = utfc_ptr2len(arg);
                 if (i > 1) {
                   // copy multibyte char
                   memmove(s, arg, (size_t)i);
                   arg += i;
                   s += i;
                 } else {
-                  *s++ = *arg++;
+                  *s++ = (uint8_t)(*arg++);
                 }
               }
               *s = NUL;
@@ -1622,7 +1622,7 @@ int do_set(char_u *arg, int opt_flags)
               }
 
               if (save_arg != NULL) {               // number for 'whichwrap'
-                arg = save_arg;
+                arg = (char *)save_arg;
               }
               new_value_alloced = true;
             }
@@ -1710,7 +1710,7 @@ skip:
             arg++;
           }
         }
-        arg = (char_u *)skipwhite((char *)arg);
+        arg = skipwhite(arg);
         if (*arg != '=') {
           break;
         }
@@ -1720,12 +1720,12 @@ skip:
     if (errmsg != NULL) {
       STRLCPY(IObuff, _(errmsg), IOSIZE);
       i = (int)STRLEN(IObuff) + 2;
-      if (i + (arg - startarg) < IOSIZE) {
+      if (i + ((char_u *)arg - startarg) < IOSIZE) {
         // append the argument with the error
         STRCAT(IObuff, ": ");
-        assert(arg >= startarg);
-        memmove(IObuff + i, startarg, (size_t)(arg - startarg));
-        IObuff[i + (arg - startarg)] = NUL;
+        assert((char_u *)arg >= startarg);
+        memmove(IObuff + i, startarg, (size_t)((char_u *)arg - startarg));
+        IObuff[i + ((char_u *)arg - startarg)] = NUL;
       }
       // make sure all characters are printable
       trans_characters(IObuff, IOSIZE);
@@ -1737,7 +1737,7 @@ skip:
       return FAIL;
     }
 
-    arg = (char_u *)skipwhite((char *)arg);
+    arg = skipwhite(arg);
   }
 
 theend:
@@ -2181,11 +2181,11 @@ static int shada_idx = -1;
 /// "set_sid".
 ///
 /// @param opt_flags  OPT_FREE, OPT_LOCAL and/or OPT_GLOBAL
-void set_string_option_direct(const char *name, int opt_idx, const char_u *val, int opt_flags,
+void set_string_option_direct(const char *name, int opt_idx, const char *val, int opt_flags,
                               int set_sid)
 {
-  char_u *s;
-  char_u **varp;
+  char *s;
+  char **varp;
   int both = (opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0;
   int idx = opt_idx;
 
@@ -2204,18 +2204,17 @@ void set_string_option_direct(const char *name, int opt_idx, const char_u *val,
 
   assert((void *)options[idx].var != (void *)&p_shada);
 
-  s = vim_strsave(val);
+  s = xstrdup(val);
   {
-    varp = (char_u **)get_varp_scope(&(options[idx]),
-                                     both ? OPT_LOCAL : opt_flags);
+    varp = (char **)get_varp_scope(&(options[idx]), both ? OPT_LOCAL : opt_flags);
     if ((opt_flags & OPT_FREE) && (options[idx].flags & P_ALLOCED)) {
-      free_string_option(*varp);
+      free_string_option((char_u *)(*varp));
     }
     *varp = s;
 
     // For buffer/window local option may also set the global value.
     if (both) {
-      set_string_option_global(idx, varp);
+      set_string_option_global(idx, (char_u **)varp);
     }
 
     options[idx].flags |= P_ALLOCED;
@@ -2223,8 +2222,8 @@ void set_string_option_direct(const char *name, int opt_idx, const char_u *val,
     /* When setting both values of a global option with a local value,
     * make the local value empty, so that the global value is used. */
     if (((int)options[idx].indir & PV_BOTH) && both) {
-      free_string_option(*varp);
-      *varp = empty_option;
+      free_string_option((char_u *)(*varp));
+      *varp = (char *)empty_option;
     }
     if (set_sid != SID_NONE) {
       sctx_T script_ctx;
@@ -2814,7 +2813,7 @@ ambw_end:
     }
   } else if (gvarp == &p_sbr) {  // 'showbreak'
     for (s = *varp; *s;) {
-      if (ptr2cells(s) != 1) {
+      if (ptr2cells((char *)s) != 1) {
         errmsg = N_("E595: 'showbreak' contains unprintable or wide character");
       }
       MB_PTR_ADV(s);
@@ -2834,7 +2833,7 @@ ambw_end:
     int flagval = (varp == &p_titlestring) ? STL_IN_TITLE : STL_IN_ICON;
 
     // NULL => statusline syntax
-    if (vim_strchr((char *)(*varp), '%') && check_stl_option(*varp) == NULL) {
+    if (vim_strchr((char *)(*varp), '%') && check_stl_option((char *)(*varp)) == NULL) {
       stl_syntax |= flagval;
     } else {
       stl_syntax &= ~flagval;
@@ -2943,14 +2942,14 @@ ambw_end:
         s++;
       }
       wid = getdigits_int(&s, true, 0);
-      if (wid && *s == '(' && (errmsg = check_stl_option(p_ruf)) == NULL) {
+      if (wid && *s == '(' && (errmsg = check_stl_option((char *)p_ruf)) == NULL) {
         ru_wid = wid;
       } else {
-        errmsg = check_stl_option(p_ruf);
+        errmsg = check_stl_option((char *)p_ruf);
       }
     } else if (varp == &p_ruf || s[0] != '%' || s[1] != '!') {
       // check 'statusline', 'winbar' or 'tabline' only if it doesn't start with "%!"
-      errmsg = check_stl_option(s);
+      errmsg = check_stl_option((char *)s);
     }
     if (varp == &p_ruf && errmsg == NULL) {
       comp_col();
@@ -3786,7 +3785,7 @@ static char *set_chars_option(win_T *wp, char_u **varp, bool set)
 
 /// Check validity of options with the 'statusline' format.
 /// Return an untranslated error message or NULL.
-char *check_stl_option(char_u *s)
+char *check_stl_option(char *s)
 {
   int groupdepth = 0;
   static char errbuf[80];
@@ -5325,7 +5324,7 @@ static void showoptions(int all, int opt_flags)
           len = 1;                      // a toggle option fits always
         } else {
           option_value2string(p, opt_flags);
-          len = (int)STRLEN(p->fullname) + vim_strsize(NameBuff) + 1;
+          len = (int)STRLEN(p->fullname) + vim_strsize((char *)NameBuff) + 1;
         }
         if ((len <= INC - GAP && run == 1)
             || (len > INC - GAP && run == 2)) {
@@ -5438,7 +5437,7 @@ static void showoneopt(vimoption_T *p, int opt_flags)
     msg_putchar('=');
     // put value string in NameBuff
     option_value2string(p, opt_flags);
-    msg_outtrans(NameBuff);
+    msg_outtrans((char *)NameBuff);
   }
 
   silent_mode = save_silent;
@@ -5631,7 +5630,7 @@ static int put_setstring(FILE *fd, char *cmd, char *name, char_u **valuep, uint6
 
       // replace home directory in the whole option value into "buf"
       buf = xmalloc(size);
-      home_replace(NULL, *valuep, buf, size, false);
+      home_replace(NULL, (char *)(*valuep), (char *)buf, size, false);
 
       // If the option value is longer than MAXPATHL, we need to append
       // each comma separated part of the option separately, so that it
@@ -7042,7 +7041,7 @@ static void option_value2string(vimoption_T *opp, int opt_flags)
     if (varp == NULL) {  // Just in case.
       NameBuff[0] = NUL;
     } else if (opp->flags & P_EXPAND) {
-      home_replace(NULL, varp, NameBuff, MAXPATHL, false);
+      home_replace(NULL, (char *)varp, (char *)NameBuff, MAXPATHL, false);
       // Translate 'pastetoggle' into special key names.
     } else if ((char_u **)opp->var == &p_pt) {
       str2specialbuf((const char *)p_pt, (char *)NameBuff, MAXPATHL);
@@ -7963,11 +7962,7 @@ void set_fileformat(int eol_style, int opt_flags)
 
   // p is NULL if "eol_style" is EOL_UNKNOWN.
   if (p != NULL) {
-    set_string_option_direct("ff",
-                             -1,
-                             (char_u *)p,
-                             OPT_FREE | opt_flags,
-                             0);
+    set_string_option_direct("ff", -1, p, OPT_FREE | opt_flags, 0);
   }
 
   // This may cause the buffer to become (un)modified.
diff --git a/src/nvim/os/env.c b/src/nvim/os/env.c
index 4bc003bc7f..3a213605dc 100644
--- a/src/nvim/os/env.c
+++ b/src/nvim/os/env.c
@@ -1033,7 +1033,7 @@ char *vim_getenv(const char *name)
 ///                  a list of them.
 ///
 /// @return length of the string put into dst, does not include NUL byte.
-size_t home_replace(const buf_T *const buf, const char_u *src, char_u *const dst, size_t dstlen,
+size_t home_replace(const buf_T *const buf, const char *src, char *const dst, size_t dstlen,
                     const bool one)
   FUNC_ATTR_NONNULL_ARG(3)
 {
@@ -1085,9 +1085,9 @@ size_t home_replace(const buf_T *const buf, const char_u *src, char_u *const dst
   }
 
   if (!one) {
-    src = (char_u *)skipwhite((char *)src);
+    src = skipwhite((char *)src);
   }
-  char *dst_p = (char *)dst;
+  char *dst_p = dst;
   while (*src && dstlen > 0) {
     // Here we are at the beginning of a file name.
     // First, check to see if the beginning of the file name matches
@@ -1123,11 +1123,11 @@ size_t home_replace(const buf_T *const buf, const char_u *src, char_u *const dst
 
     // if (!one) skip to separator: space or comma.
     while (*src && (one || (*src != ',' && *src != ' ')) && --dstlen > 0) {
-      *dst_p++ = (char)(*src++);
+      *dst_p++ = *src++;
     }
     // Skip separator.
     while ((*src == ' ' || *src == ',') && --dstlen > 0) {
-      *dst_p++ = (char)(*src++);
+      *dst_p++ = *src++;
     }
   }
   // If (dstlen == 0) out of space, what to do???
@@ -1137,7 +1137,7 @@ size_t home_replace(const buf_T *const buf, const char_u *src, char_u *const dst
   if (must_free) {
     xfree(homedir_env_mod);
   }
-  return (size_t)(dst_p - (char *)dst);
+  return (size_t)(dst_p - dst);
 }
 
 /// Like home_replace, store the replaced string in allocated memory.
@@ -1149,9 +1149,9 @@ char_u *home_replace_save(buf_T *buf, char_u *src) FUNC_ATTR_NONNULL_RET
   if (src != NULL) {          // just in case
     len += STRLEN(src);
   }
-  char_u *dst = xmalloc(len);
-  home_replace(buf, src, dst, len, true);
-  return dst;
+  char *dst = xmalloc(len);
+  home_replace(buf, (char *)src, dst, len, true);
+  return (char_u *)dst;
 }
 
 /// Function given to ExpandGeneric() to obtain an environment variable name.
diff --git a/src/nvim/os/shell.c b/src/nvim/os/shell.c
index d331bd21a2..9283ea2e42 100644
--- a/src/nvim/os/shell.c
+++ b/src/nvim/os/shell.c
@@ -854,9 +854,9 @@ static int do_os_system(char **argv, const char *input, size_t len, char **outpu
     // Failed, probably 'shell' is not executable.
     if (!silent) {
       msg_puts(_("\nshell failed to start: "));
-      msg_outtrans((char_u *)os_strerror(status));
+      msg_outtrans((char *)os_strerror(status));
       msg_puts(": ");
-      msg_outtrans((char_u *)prog);
+      msg_outtrans(prog);
       msg_putchar('\n');
     }
     multiqueue_free(events);
diff --git a/src/nvim/path.c b/src/nvim/path.c
index 9859ca7daa..f5c662ca88 100644
--- a/src/nvim/path.c
+++ b/src/nvim/path.c
@@ -52,27 +52,27 @@
 /// @param checkname When both files don't exist, only compare their names.
 /// @param expandenv Whether to expand environment variables in file names.
 /// @return Enum of type FileComparison. @see FileComparison.
-FileComparison path_full_compare(char_u *const s1, char_u *const s2, const bool checkname,
+FileComparison path_full_compare(char *const s1, char *const s2, const bool checkname,
                                  const bool expandenv)
 {
   assert(s1 && s2);
-  char_u exp1[MAXPATHL];
-  char_u full1[MAXPATHL];
-  char_u full2[MAXPATHL];
+  char exp1[MAXPATHL];
+  char full1[MAXPATHL];
+  char full2[MAXPATHL];
   FileID file_id_1, file_id_2;
 
   if (expandenv) {
-    expand_env(s1, exp1, MAXPATHL);
+    expand_env((char_u *)s1, (char_u *)exp1, MAXPATHL);
   } else {
     STRLCPY(exp1, s1, MAXPATHL);
   }
-  bool id_ok_1 = os_fileid((char *)exp1, &file_id_1);
-  bool id_ok_2 = os_fileid((char *)s2, &file_id_2);
+  bool id_ok_1 = os_fileid(exp1, &file_id_1);
+  bool id_ok_2 = os_fileid(s2, &file_id_2);
   if (!id_ok_1 && !id_ok_2) {
     // If os_fileid() doesn't work, may compare the names.
     if (checkname) {
-      vim_FullName((char *)exp1, (char *)full1, MAXPATHL, false);
-      vim_FullName((char *)s2, (char *)full2, MAXPATHL, false);
+      vim_FullName(exp1, full1, MAXPATHL, false);
+      vim_FullName(s2, full2, MAXPATHL, false);
       if (FNAMECMP(full1, full2) == 0) {
         return kEqualFileNames;
       }
diff --git a/src/nvim/plines.c b/src/nvim/plines.c
index 35f2512ee3..70bdbd8b1d 100644
--- a/src/nvim/plines.c
+++ b/src/nvim/plines.c
@@ -229,7 +229,7 @@ int win_chartabsize(win_T *wp, char_u *p, colnr_T col)
   if (*p == TAB && (!wp->w_p_list || wp->w_p_lcs_chars.tab1)) {
     return tabstop_padding(col, buf->b_p_ts, buf->b_p_vts_array);
   } else {
-    return ptr2cells(p);
+    return ptr2cells((char *)p);
   }
 }
 
@@ -408,7 +408,7 @@ int win_lbr_chartabsize(win_T *wp, char_u *line, char_u *s, colnr_T col, int *he
   // Set *headp to the size of what we add.
   added = 0;
 
-  char_u *const sbr = get_showbreak_value(wp);
+  char *const sbr = (char *)get_showbreak_value(wp);
   if ((*sbr != NUL || wp->w_p_bri) && wp->w_p_wrap && col != 0) {
     colnr_T sbrlen = 0;
     int numberwidth = win_col_off(wp);
@@ -423,7 +423,7 @@ int win_lbr_chartabsize(win_T *wp, char_u *line, char_u *s, colnr_T col, int *he
         col %= numberextra;
       }
       if (*sbr != NUL) {
-        sbrlen = (colnr_T)mb_charlen(sbr);
+        sbrlen = (colnr_T)mb_charlen((char_u *)sbr);
         if (col >= sbrlen) {
           col -= sbrlen;
         }
@@ -494,7 +494,7 @@ static int win_nolbr_chartabsize(win_T *wp, char_u *s, colnr_T col, int *headp)
                            wp->w_buffer->b_p_ts,
                            wp->w_buffer->b_p_vts_array);
   }
-  n = ptr2cells(s);
+  n = ptr2cells((char *)s);
 
   // Add one cell for a double-width character in the last column of the
   // window, displayed with a ">".
diff --git a/src/nvim/popupmnu.c b/src/nvim/popupmnu.c
index db1054eb1f..ecaeca005d 100644
--- a/src/nvim/popupmnu.c
+++ b/src/nvim/popupmnu.c
@@ -66,19 +66,19 @@ static void pum_compute_size(void)
   for (int i = 0; i < pum_size; i++) {
     int w;
     if (pum_array[i].pum_text != NULL) {
-      w = vim_strsize(pum_array[i].pum_text);
+      w = vim_strsize((char *)pum_array[i].pum_text);
       if (pum_base_width < w) {
         pum_base_width = w;
       }
     }
     if (pum_array[i].pum_kind != NULL) {
-      w = vim_strsize(pum_array[i].pum_kind) + 1;
+      w = vim_strsize((char *)pum_array[i].pum_kind) + 1;
       if (pum_kind_width < w) {
         pum_kind_width = w;
       }
     }
     if (pum_array[i].pum_extra != NULL) {
-      w = vim_strsize(pum_array[i].pum_extra) + 1;
+      w = vim_strsize((char *)pum_array[i].pum_extra) + 1;
       if (pum_extra_width < w) {
         pum_extra_width = w;
       }
@@ -504,7 +504,7 @@ void pum_redraw(void)
           if (s == NULL) {
             s = p;
           }
-          w = ptr2cells(p);
+          w = ptr2cells((char *)p);
 
           if ((*p == NUL) || (*p == TAB) || (totwidth + w > pum_width)) {
             // Display the text that fits or comes before a Tab.
@@ -517,13 +517,13 @@ void pum_redraw(void)
             *p = saved;
 
             if (pum_rl) {
-              char_u *rt = reverse_text(st);
-              char_u *rt_start = rt;
+              char *rt = (char *)reverse_text(st);
+              char *rt_start = rt;
               int size = vim_strsize(rt);
 
               if (size > pum_width) {
                 do {
-                  size -= utf_ptr2cells((char *)rt);
+                  size -= utf_ptr2cells(rt);
                   MB_PTR_ADV(rt);
                 } while (size > pum_width);
 
@@ -535,7 +535,7 @@ void pum_redraw(void)
                   size++;
                 }
               }
-              grid_puts_len(&pum_grid, rt, (int)STRLEN(rt), row,
+              grid_puts_len(&pum_grid, (char_u *)rt, (int)STRLEN(rt), row,
                             grid_col - size + 1, attr);
               xfree(rt_start);
               xfree(st);
diff --git a/src/nvim/quickfix.c b/src/nvim/quickfix.c
index 868a68969c..22e72669ee 100644
--- a/src/nvim/quickfix.c
+++ b/src/nvim/quickfix.c
@@ -4343,7 +4343,7 @@ static char *make_get_fullcmd(const char *makecmd, const char *fname)
   }
   msg_start();
   msg_puts(":!");
-  msg_outtrans((char_u *)cmd);  // show what we are doing
+  msg_outtrans(cmd);  // show what we are doing
 
   return cmd;
 }
@@ -5100,7 +5100,7 @@ void ex_cfile(exarg_T *eap)
     }
   }
   if (*eap->arg != NUL) {
-    set_string_option_direct("ef", -1, (char_u *)eap->arg, OPT_FREE, 0);
+    set_string_option_direct("ef", -1, eap->arg, OPT_FREE, 0);
   }
 
   char *enc = (*curbuf->b_p_menc != NUL) ? (char *)curbuf->b_p_menc : (char *)p_menc;
@@ -5199,9 +5199,9 @@ static void vgr_display_fname(char *fname)
   msg_start();
   char *p = (char *)msg_strtrunc((char_u *)fname, true);
   if (p == NULL) {
-    msg_outtrans((char_u *)fname);
+    msg_outtrans(fname);
   } else {
-    msg_outtrans((char_u *)p);
+    msg_outtrans(p);
     xfree(p);
   }
   msg_clr_eos();
@@ -5716,7 +5716,7 @@ static buf_T *load_dummy_buffer(char *fname, char *dirname_start, char *resultin
     aucmd_prepbuf(&aco, newbuf);
 
     // Need to set the filename for autocommands.
-    (void)setfname(curbuf, (char_u *)fname, NULL, false);
+    (void)setfname(curbuf, fname, NULL, false);
 
     // Create swap file now to avoid the ATTENTION message.
     check_need_swap(true);
diff --git a/src/nvim/screen.c b/src/nvim/screen.c
index 98f8e30391..ea75900ded 100644
--- a/src/nvim/screen.c
+++ b/src/nvim/screen.c
@@ -4718,7 +4718,7 @@ static int status_match_len(expand_T *xp, char_u *s)
 
   while (*s != NUL) {
     s += skip_status_match_char(xp, s);
-    len += ptr2cells(s);
+    len += ptr2cells((char *)s);
     MB_PTR_ADV(s);
   }
 
@@ -4856,7 +4856,7 @@ void win_redr_status_matches(expand_T *xp, int num_matches, char_u **matches, in
     } else {
       for (; *s != NUL; ++s) {
         s += skip_status_match_char(xp, s);
-        clen += ptr2cells(s);
+        clen += ptr2cells((char *)s);
         if ((l = utfc_ptr2len((char *)s)) > 1) {
           STRNCPY(buf + len, s, l);  // NOLINT(runtime/printf)
           s += l - 1;
@@ -5034,7 +5034,7 @@ static void win_redr_status(win_T *wp)
     grid_fill(&default_grid, row, row + 1, len + col,
               this_ru_col + col, fillchar, fillchar, attr);
 
-    if (get_keymap_str(wp, (char_u *)"<%s>", NameBuff, MAXPATHL)
+    if (get_keymap_str(wp, "<%s>", (char *)NameBuff, MAXPATHL)
         && this_ru_col - len > (int)(STRLEN(NameBuff) + 1)) {
       grid_puts(&default_grid, NameBuff, row,
                 (int)(this_ru_col - STRLEN(NameBuff) - 1), attr);
@@ -5079,7 +5079,7 @@ static void redraw_custom_statusline(win_T *wp)
     // When there is an error disable the statusline, otherwise the
     // display is messed up with errors and a redraw triggers the problem
     // again and again.
-    set_string_option_direct("statusline", -1, (char_u *)"",
+    set_string_option_direct("statusline", -1, "",
                              OPT_FREE | (*wp->w_p_stl != NUL
                                          ? OPT_LOCAL : OPT_GLOBAL), SID_ERROR);
   }
@@ -5109,7 +5109,7 @@ static void win_redr_winbar(win_T *wp)
       // When there is an error disable the winbar, otherwise the
       // display is messed up with errors and a redraw triggers the problem
       // again and again.
-      set_string_option_direct("winbar", -1, (char_u *)"",
+      set_string_option_direct("winbar", -1, "",
                                OPT_FREE | (*wp->w_p_stl != NUL
                                            ? OPT_LOCAL : OPT_GLOBAL), SID_ERROR);
     }
@@ -5218,9 +5218,9 @@ static bool vsep_connected(win_T *wp, WindowCorner corner)
 /// @param fmt  format string containing one %s item
 /// @param buf  buffer for the result
 /// @param len  length of buffer
-bool get_keymap_str(win_T *wp, char_u *fmt, char_u *buf, int len)
+bool get_keymap_str(win_T *wp, char *fmt, char *buf, int len)
 {
-  char_u *p;
+  char *p;
 
   if (wp->w_buffer->b_p_iminsert != B_IMODE_LMAP) {
     return false;
@@ -5229,24 +5229,24 @@ bool get_keymap_str(win_T *wp, char_u *fmt, char_u *buf, int len)
   {
     buf_T *old_curbuf = curbuf;
     win_T *old_curwin = curwin;
-    char_u *s;
+    char *s;
 
     curbuf = wp->w_buffer;
     curwin = wp;
     STRCPY(buf, "b:keymap_name");       // must be writable
     emsg_skip++;
-    s = p = (char_u *)eval_to_string((char *)buf, NULL, false);
+    s = p = eval_to_string(buf, NULL, false);
     emsg_skip--;
     curbuf = old_curbuf;
     curwin = old_curwin;
     if (p == NULL || *p == NUL) {
       if (wp->w_buffer->b_kmap_state & KEYMAP_LOADED) {
-        p = wp->w_buffer->b_p_keymap;
+        p = (char *)wp->w_buffer->b_p_keymap;
       } else {
-        p = (char_u *)"lang";
+        p = "lang";
       }
     }
-    if (vim_snprintf((char *)buf, len, (char *)fmt, p) > len - 1) {
+    if (vim_snprintf(buf, len, fmt, p) > len - 1) {
       buf[0] = NUL;
     }
     xfree(s);
@@ -5268,9 +5268,9 @@ static void win_redr_custom(win_T *wp, bool draw_winbar, bool draw_ruler)
   int n;
   int len;
   int fillchar;
-  char_u buf[MAXPATHL];
+  char buf[MAXPATHL];
   char_u *stl;
-  char_u *p;
+  char *p;
   stl_hlrec_t *hltab;
   StlClickRecord *tabtab;
   int use_sandbox = false;
@@ -5389,20 +5389,20 @@ static void win_redr_custom(win_T *wp, bool draw_winbar, bool draw_ruler)
    * might change the option value and free the memory. */
   stl = vim_strsave(stl);
   width =
-    build_stl_str_hl(ewp, (char *)buf, sizeof(buf), (char *)stl, use_sandbox,
+    build_stl_str_hl(ewp, buf, sizeof(buf), (char *)stl, use_sandbox,
                      fillchar, maxwidth, &hltab, &tabtab);
   xfree(stl);
   ewp->w_p_crb = p_crb_save;
 
   // Make all characters printable.
-  p = (char_u *)transstr((const char *)buf, true);
+  p = transstr(buf, true);
   len = STRLCPY(buf, p, sizeof(buf));
   len = (size_t)len < sizeof(buf) ? len : (int)sizeof(buf) - 1;
   xfree(p);
 
   // fill up with "fillchar"
   while (width < maxwidth && len < (int)sizeof(buf) - 1) {
-    len += utf_char2bytes(fillchar, (char *)buf + len);
+    len += utf_char2bytes(fillchar, buf + len);
     width++;
   }
   buf[len] = NUL;
@@ -5416,8 +5416,8 @@ static void win_redr_custom(win_T *wp, bool draw_winbar, bool draw_ruler)
   p = buf;
   for (n = 0; hltab[n].start != NULL; n++) {
     int textlen = (int)(hltab[n].start - p);
-    grid_puts_len(grid, p, textlen, row, col, curattr);
-    col += vim_strnsize(p, textlen);
+    grid_puts_len(grid, (char_u *)p, textlen, row, col, curattr);
+    col += vim_strnsize((char_u *)p, textlen);
     p = hltab[n].start;
 
     if (hltab[n].userhl == 0) {
@@ -5431,7 +5431,7 @@ static void win_redr_custom(win_T *wp, bool draw_winbar, bool draw_ruler)
     }
   }
   // Make sure to use an empty string instead of p, if p is beyond buf + len.
-  grid_puts(grid, p >= buf + len ? (char_u *)"" : p, row, col,
+  grid_puts(grid, p >= buf + len ? (char_u *)"" : (char_u *)p, row, col,
             curattr);
 
   grid_puts_line_flush(false);
@@ -5453,11 +5453,11 @@ static void win_redr_custom(win_T *wp, bool draw_winbar, bool draw_ruler)
     .type = kStlClickDisabled,
   };
   for (n = 0; tabtab[n].start != NULL; n++) {
-    len += vim_strnsize(p, (int)(tabtab[n].start - (char *)p));
+    len += vim_strnsize((char_u *)p, (int)(tabtab[n].start - p));
     while (col < len) {
       click_defs[col++] = cur_click_def;
     }
-    p = (char_u *)tabtab[n].start;
+    p = (char *)tabtab[n].start;
     cur_click_def = tabtab[n].def;
     if ((wp != NULL) && !(cur_click_def.type == kStlClickDisabled
                           || cur_click_def.type == kStlClickFuncRun)) {
@@ -5980,13 +5980,13 @@ int showmode(void)
           length = (Rows - msg_row) * Columns - 3;
         }
         if (edit_submode_extra != NULL) {
-          length -= vim_strsize(edit_submode_extra);
+          length -= vim_strsize((char *)edit_submode_extra);
         }
         if (length > 0) {
           if (edit_submode_pre != NULL) {
-            length -= vim_strsize(edit_submode_pre);
+            length -= vim_strsize((char *)edit_submode_pre);
           }
-          if (length - vim_strsize(edit_submode) > 0) {
+          if (length - vim_strsize((char *)edit_submode) > 0) {
             if (edit_submode_pre != NULL) {
               msg_puts_attr((const char *)edit_submode_pre, attr);
             }
@@ -6028,8 +6028,8 @@ int showmode(void)
         if (State & MODE_LANGMAP) {
           if (curwin->w_p_arab) {
             msg_puts_attr(_(" Arabic"), attr);
-          } else if (get_keymap_str(curwin, (char_u *)" (%s)",
-                                    NameBuff, MAXPATHL)) {
+          } else if (get_keymap_str(curwin, " (%s)",
+                                    (char *)NameBuff, MAXPATHL)) {
             msg_puts_attr((char *)NameBuff, attr);
           }
         }
@@ -6211,8 +6211,7 @@ void draw_tabline(void)
     did_emsg = false;
     win_redr_custom(NULL, false, false);
     if (did_emsg) {
-      set_string_option_direct("tabline", -1,
-                               (char_u *)"", OPT_FREE, SID_ERROR);
+      set_string_option_direct("tabline", -1, "", OPT_FREE, SID_ERROR);
     }
     did_emsg |= saved_did_emsg;
   } else {
@@ -6289,10 +6288,10 @@ void draw_tabline(void)
         // Get buffer name in NameBuff[]
         get_trans_bufname(cwp->w_buffer);
         shorten_dir(NameBuff);
-        len = vim_strsize(NameBuff);
+        len = vim_strsize((char *)NameBuff);
         p = NameBuff;
         while (len > room) {
-          len -= ptr2cells(p);
+          len -= ptr2cells((char *)p);
           MB_PTR_ADV(p);
         }
         if (len > Columns - col - 1) {
@@ -6395,7 +6394,7 @@ void get_trans_bufname(buf_T *buf)
   if (buf_spname(buf) != NULL) {
     STRLCPY(NameBuff, buf_spname(buf), MAXPATHL);
   } else {
-    home_replace(buf, (char_u *)buf->b_fname, NameBuff, MAXPATHL, true);
+    home_replace(buf, buf->b_fname, (char *)NameBuff, MAXPATHL, true);
   }
   trans_characters(NameBuff, MAXPATHL);
 }
@@ -6521,8 +6520,7 @@ static void win_redr_ruler(win_T *wp, bool always)
     called_emsg = false;
     win_redr_custom(wp, false, true);
     if (called_emsg) {
-      set_string_option_direct("rulerformat", -1, (char_u *)"",
-                               OPT_FREE, SID_ERROR);
+      set_string_option_direct("rulerformat", -1, "", OPT_FREE, SID_ERROR);
     }
     called_emsg |= save_called_emsg;
     return;
@@ -6588,17 +6586,17 @@ static void win_redr_ruler(win_T *wp, bool always)
     }
 
 #define RULER_BUF_LEN 70
-    char_u buffer[RULER_BUF_LEN];
+    char buffer[RULER_BUF_LEN];
 
     /*
      * Some sprintfs return the length, some return a pointer.
      * To avoid portability problems we use strlen() here.
      */
-    vim_snprintf((char *)buffer, RULER_BUF_LEN, "%" PRId64 ",",
+    vim_snprintf(buffer, RULER_BUF_LEN, "%" PRId64 ",",
                  (wp->w_buffer->b_ml.ml_flags & ML_EMPTY) ? (int64_t)0L
                                                           : (int64_t)wp->w_cursor.lnum);
     size_t len = STRLEN(buffer);
-    col_print(buffer + len, RULER_BUF_LEN - len,
+    col_print((char_u *)buffer + len, RULER_BUF_LEN - len,
               empty_line ? 0 : (int)wp->w_cursor.col + 1,
               (int)virtcol + 1);
 
@@ -6625,7 +6623,7 @@ static void win_redr_ruler(win_T *wp, bool always)
     if (this_ru_col + o < width) {
       // Need at least 3 chars left for get_rel_pos() + NUL.
       while (this_ru_col + o < width && RULER_BUF_LEN > i + 4) {
-        i += utf_char2bytes(fillchar, (char *)buffer + i);
+        i += utf_char2bytes(fillchar, buffer + i);
         o++;
       }
       get_rel_pos(wp, buffer + i, RULER_BUF_LEN - i);
@@ -6646,8 +6644,8 @@ static void win_redr_ruler(win_T *wp, bool always)
       }
       // Truncate at window boundary.
       o = 0;
-      for (i = 0; buffer[i] != NUL; i += utfc_ptr2len((char *)buffer + i)) {
-        o += utf_ptr2cells((char *)buffer + i);
+      for (i = 0; buffer[i] != NUL; i += utfc_ptr2len(buffer + i)) {
+        o += utf_ptr2cells(buffer + i);
         if (this_ru_col + o > width) {
           buffer[i] = NUL;
           break;
@@ -6655,7 +6653,7 @@ static void win_redr_ruler(win_T *wp, bool always)
       }
 
       ScreenGrid *grid = part_of_status ? &default_grid : &msg_grid_adj;
-      grid_puts(grid, buffer, row, this_ru_col + off, attr);
+      grid_puts(grid, (char_u *)buffer, row, this_ru_col + off, attr);
       grid_fill(grid, row, row + 1,
                 this_ru_col + off + (int)STRLEN(buffer), off + width, fillchar,
                 fillchar, attr);
diff --git a/src/nvim/search.c b/src/nvim/search.c
index 1e862f10ec..a5c18bd03a 100644
--- a/src/nvim/search.c
+++ b/src/nvim/search.c
@@ -910,8 +910,7 @@ int searchit(win_T *win, buf_T *buf, pos_T *pos, pos_T *end_pos, Direction dir,
         lnum = 1;
       }
       if (!shortmess(SHM_SEARCH) && (options & SEARCH_MSG)) {
-        give_warning((char_u *)_(dir == BACKWARD
-                                 ? top_bot_msg : bot_top_msg), true);
+        give_warning(_(dir == BACKWARD ? top_bot_msg : bot_top_msg), true);
       }
       if (extra_arg != NULL) {
         extra_arg->sa_wrapped = true;
@@ -1261,7 +1260,7 @@ int do_search(oparg_T *oap, int dirc, int search_delim, char_u *pat, long count,
             memset(msgbuf + pat_len, ' ', r - msgbuf);
           }
         }
-        msg_outtrans(msgbuf);
+        msg_outtrans((char *)msgbuf);
         msg_clr_eos();
         msg_check();
 
@@ -1452,7 +1451,7 @@ int search_for_exact_line(buf_T *buf, pos_T *pos, Direction dir, char_u *pat)
       if (p_ws) {
         pos->lnum = buf->b_ml.ml_line_count;
         if (!shortmess(SHM_SEARCH)) {
-          give_warning((char_u *)_(top_bot_msg), true);
+          give_warning(_(top_bot_msg), true);
         }
       } else {
         pos->lnum = 1;
@@ -1462,7 +1461,7 @@ int search_for_exact_line(buf_T *buf, pos_T *pos, Direction dir, char_u *pat)
       if (p_ws) {
         pos->lnum = 1;
         if (!shortmess(SHM_SEARCH)) {
-          give_warning((char_u *)_(bot_top_msg), true);
+          give_warning(_(bot_top_msg), true);
         }
       } else {
         pos->lnum = 1;
@@ -4515,7 +4514,7 @@ static void cmdline_search_stat(int dirc, pos_T *pos, pos_T *cursor_pos, bool sh
     // keep the message even after redraw, but don't put in history
     msg_hist_off = true;
     msg_ext_set_kind("search_count");
-    give_warning(msgbuf, false);
+    give_warning((char *)msgbuf, false);
     msg_hist_off = false;
   }
 }
@@ -5414,8 +5413,8 @@ void find_pattern_in_path(char_u *ptr, Direction dir, size_t len, bool whole, bo
           if (i == max_path_depth) {
             break;
           }
-          if (path_full_compare(new_fname, files[i].name,
-                                true, true) & kEqualFiles) {
+          if (path_full_compare((char *)new_fname, (char *)files[i].name, true,
+                                true) & kEqualFiles) {
             if (type != CHECK_PATH
                 && action == ACTION_SHOW_ALL && files[i].matched) {
               msg_putchar('\n');  // cursor below last one */
diff --git a/src/nvim/shada.c b/src/nvim/shada.c
index 5410740d9e..32a0f3902d 100644
--- a/src/nvim/shada.c
+++ b/src/nvim/shada.c
@@ -3977,7 +3977,7 @@ static bool shada_removable(const char *name)
   for (p = (char *)p_shada; *p;) {
     (void)copy_option_part((char_u **)&p, (char_u *)part, ARRAY_SIZE(part), ", ");
     if (part[0] == 'r') {
-      home_replace(NULL, (char_u *)(part + 1), (char_u *)NameBuff, MAXPATHL, true);
+      home_replace(NULL, part + 1, (char *)NameBuff, MAXPATHL, true);
       size_t n = STRLEN(NameBuff);
       if (mb_strnicmp((char_u *)NameBuff, (char_u *)new_name, n) == 0) {
         retval = true;
diff --git a/src/nvim/sign.c b/src/nvim/sign.c
index a5adc48540..24da650743 100644
--- a/src/nvim/sign.c
+++ b/src/nvim/sign.c
@@ -1624,12 +1624,12 @@ static void sign_list_defined(sign_T *sp)
   smsg("sign %s", sp->sn_name);
   if (sp->sn_icon != NULL) {
     msg_puts(" icon=");
-    msg_outtrans(sp->sn_icon);
+    msg_outtrans((char *)sp->sn_icon);
     msg_puts(_(" (not supported)"));
   }
   if (sp->sn_text != NULL) {
     msg_puts(" text=");
-    msg_outtrans(sp->sn_text);
+    msg_outtrans((char *)sp->sn_text);
   }
   if (sp->sn_line_hl > 0) {
     msg_puts(" linehl=");
diff --git a/src/nvim/spell.c b/src/nvim/spell.c
index 8ae846e074..e4805f3c4a 100644
--- a/src/nvim/spell.c
+++ b/src/nvim/spell.c
@@ -1576,7 +1576,7 @@ size_t spell_move_to(win_T *wp, int dir, bool allwords, bool curline, hlf_T *att
         lnum = wp->w_buffer->b_ml.ml_line_count;
         wrapped = true;
         if (!shortmess(SHM_SEARCH)) {
-          give_warning((char_u *)_(top_bot_msg), true);
+          give_warning(_(top_bot_msg), true);
         }
       }
       capcol = -1;
@@ -1591,7 +1591,7 @@ size_t spell_move_to(win_T *wp, int dir, bool allwords, bool curline, hlf_T *att
         lnum = 1;
         wrapped = true;
         if (!shortmess(SHM_SEARCH)) {
-          give_warning((char_u *)_(bot_top_msg), true);
+          give_warning(_(bot_top_msg), true);
         }
       }
 
@@ -2115,7 +2115,7 @@ char *did_set_spelllang(win_T *wp)
 
       // Check if we loaded this language before.
       for (slang = first_lang; slang != NULL; slang = slang->sl_next) {
-        if (path_full_compare(lang, slang->sl_fname, false, true)
+        if (path_full_compare((char *)lang, (char *)slang->sl_fname, false, true)
             == kEqualFiles) {
           break;
         }
@@ -2164,7 +2164,7 @@ char *did_set_spelllang(win_T *wp)
     // Loop over the languages, there can be several files for "lang".
     for (slang = first_lang; slang != NULL; slang = slang->sl_next) {
       if (filename
-          ? path_full_compare(lang, slang->sl_fname, false, true) == kEqualFiles
+          ? path_full_compare((char *)lang, (char *)slang->sl_fname, false, true) == kEqualFiles
           : STRICMP(lang, slang->sl_name) == 0) {
         region_mask = REGION_ALL;
         if (!filename && region != NULL) {
@@ -2222,7 +2222,7 @@ char *did_set_spelllang(win_T *wp)
       for (c = 0; c < ga.ga_len; ++c) {
         p = LANGP_ENTRY(ga, c)->lp_slang->sl_fname;
         if (p != NULL
-            && path_full_compare(spf_name, p, false, true) == kEqualFiles) {
+            && path_full_compare((char *)spf_name, (char *)p, false, true) == kEqualFiles) {
           break;
         }
       }
@@ -2233,7 +2233,7 @@ char *did_set_spelllang(win_T *wp)
 
     // Check if it was loaded already.
     for (slang = first_lang; slang != NULL; slang = slang->sl_next) {
-      if (path_full_compare(spf_name, slang->sl_fname, false, true)
+      if (path_full_compare((char *)spf_name, (char *)slang->sl_fname, false, true)
           == kEqualFiles) {
         break;
       }
diff --git a/src/nvim/spellfile.c b/src/nvim/spellfile.c
index 2b6bb098d1..07f3d39886 100644
--- a/src/nvim/spellfile.c
+++ b/src/nvim/spellfile.c
@@ -1826,7 +1826,7 @@ static void spell_reload_one(char_u *fname, bool added_word)
   bool didit = false;
 
   for (slang = first_lang; slang != NULL; slang = slang->sl_next) {
-    if (path_full_compare(fname, slang->sl_fname, false, true) == kEqualFiles) {
+    if (path_full_compare((char *)fname, (char *)slang->sl_fname, false, true) == kEqualFiles) {
       slang_clear(slang);
       if (spell_load_file(fname, NULL, slang, false) == NULL) {
         // reloading failed, clear the language
@@ -4903,7 +4903,7 @@ static void spell_make_sugfile(spellinfo_T *spin, char_u *wfname)
   // of the code for the soundfolding stuff.
   // It might have been done already by spell_reload_one().
   for (slang = first_lang; slang != NULL; slang = slang->sl_next) {
-    if (path_full_compare(wfname, slang->sl_fname, false, true)
+    if (path_full_compare((char *)wfname, (char *)slang->sl_fname, false, true)
         == kEqualFiles) {
       break;
     }
@@ -5598,9 +5598,8 @@ void spell_add_word(char_u *word, int len, SpellAddType what, int idx, bool undo
           if (fseek(fd, fpos, SEEK_SET) == 0) {
             fputc('#', fd);
             if (undo) {
-              home_replace(NULL, fname, NameBuff, MAXPATHL, TRUE);
-              smsg(_("Word '%.*s' removed from %s"),
-                   len, word, NameBuff);
+              home_replace(NULL, (char *)fname, (char *)NameBuff, MAXPATHL, true);
+              smsg(_("Word '%.*s' removed from %s"), len, word, NameBuff);
             }
           }
           if (fseek(fd, fpos_next, SEEK_SET) != 0) {
@@ -5648,7 +5647,7 @@ void spell_add_word(char_u *word, int len, SpellAddType what, int idx, bool undo
       }
       fclose(fd);
 
-      home_replace(NULL, fname, NameBuff, MAXPATHL, TRUE);
+      home_replace(NULL, (char *)fname, (char *)NameBuff, MAXPATHL, true);
       smsg(_("Word '%.*s' added to %s"), len, word, NameBuff);
     }
   }
diff --git a/src/nvim/syntax.c b/src/nvim/syntax.c
index 0d43458b5b..9615423765 100644
--- a/src/nvim/syntax.c
+++ b/src/nvim/syntax.c
@@ -3171,9 +3171,9 @@ static void syn_cmd_iskeyword(exarg_T *eap, int syncing)
     msg_puts("\n");
     if (curwin->w_s->b_syn_isk != empty_option) {
       msg_puts("syntax iskeyword ");
-      msg_outtrans(curwin->w_s->b_syn_isk);
+      msg_outtrans((char *)curwin->w_s->b_syn_isk);
     } else {
-      msg_outtrans((char_u *)_("syntax iskeyword not set"));
+      msg_outtrans(_("syntax iskeyword not set"));
     }
   } else {
     if (STRNICMP(arg, "clear", 5) == 0) {
@@ -3382,7 +3382,7 @@ static void syn_cmd_clear(exarg_T *eap, int syncing)
           XFREE_CLEAR(SYN_CLSTR(curwin->w_s)[scl_id].scl_list);
         }
       } else {
-        id = syn_name2id_len(arg, (int)(arg_end - arg));
+        id = syn_name2id_len((char *)arg, (int)(arg_end - arg));
         if (id == 0) {
           semsg(_(e_nogroup), arg);
           break;
@@ -3553,7 +3553,7 @@ static void syn_cmd_list(exarg_T *eap, int syncing)
           syn_list_cluster(id - SYNID_CLUSTER);
         }
       } else {
-        int id = syn_name2id_len(arg, (int)(arg_end - arg));
+        int id = syn_name2id_len((char *)arg, (int)(arg_end - arg));
         if (id == 0) {
           semsg(_(e_nogroup), arg);
         } else {
@@ -3690,8 +3690,8 @@ static void syn_list_one(const int id, const bool syncing, const bool link_only)
       }
       msg_putchar(' ');
       if (spp->sp_sync_idx >= 0) {
-        msg_outtrans(highlight_group_name(SYN_ITEMS(curwin->w_s)
-                                          [spp->sp_sync_idx].sp_syn.id - 1));
+        msg_outtrans((char *)highlight_group_name(SYN_ITEMS(curwin->w_s)
+                                                  [spp->sp_sync_idx].sp_syn.id - 1));
       } else {
         msg_puts("NONE");
       }
@@ -3704,7 +3704,7 @@ static void syn_list_one(const int id, const bool syncing, const bool link_only)
     (void)syn_list_header(did_header, 0, id, true);
     msg_puts_attr("links to", attr);
     msg_putchar(' ');
-    msg_outtrans(highlight_group_name(highlight_link_id(id - 1) - 1));
+    msg_outtrans((char *)highlight_group_name(highlight_link_id(id - 1) - 1));
   }
 }
 
@@ -3729,7 +3729,7 @@ static void syn_list_cluster(int id)
 
   // slight hack:  roughly duplicate the guts of syn_list_header()
   msg_putchar('\n');
-  msg_outtrans(SYN_CLSTR(curwin->w_s)[id].scl_name);
+  msg_outtrans((char *)SYN_CLSTR(curwin->w_s)[id].scl_name);
 
   if (msg_col >= endcol) {      // output at least one space
     endcol = msg_col + 1;
@@ -3766,9 +3766,9 @@ static void put_id_list(const char *const name, const int16_t *const list, const
       int scl_id = *p - SYNID_CLUSTER;
 
       msg_putchar('@');
-      msg_outtrans(SYN_CLSTR(curwin->w_s)[scl_id].scl_name);
+      msg_outtrans((char *)SYN_CLSTR(curwin->w_s)[scl_id].scl_name);
     } else {
-      msg_outtrans(highlight_group_name(*p - 1));
+      msg_outtrans((char *)highlight_group_name(*p - 1));
     }
     if (p[1]) {
       msg_putchar(',');
@@ -3788,9 +3788,9 @@ static void put_pattern(const char *const s, const int c, const synpat_T *const
     msg_puts_attr("matchgroup", attr);
     msg_putchar('=');
     if (last_matchgroup == 0) {
-      msg_outtrans((char_u *)"NONE");
+      msg_outtrans("NONE");
     } else {
-      msg_outtrans(highlight_group_name(last_matchgroup - 1));
+      msg_outtrans((char *)highlight_group_name(last_matchgroup - 1));
     }
     msg_putchar(' ');
   }
@@ -3807,7 +3807,7 @@ static void put_pattern(const char *const s, const int c, const synpat_T *const
     }
   }
   msg_putchar(sepchars[i]);
-  msg_outtrans(spp->sp_pattern);
+  msg_outtrans((char *)spp->sp_pattern);
   msg_putchar(sepchars[i]);
 
   // output any pattern options
@@ -3917,7 +3917,7 @@ static bool syn_list_keywords(const int id, const hashtab_T *const ht, bool did_
             prev_skipempty = (kp->flags & HL_SKIPEMPTY);
           }
         }
-        msg_outtrans(kp->keyword);
+        msg_outtrans((char *)kp->keyword);
       }
     }
   }
@@ -6038,7 +6038,7 @@ static void syntime_report(void)
     msg_puts(profile_msg(p->average));
     msg_puts(" ");
     msg_advance(50);
-    msg_outtrans(highlight_group_name(p->id - 1));
+    msg_outtrans((char *)highlight_group_name(p->id - 1));
     msg_puts(" ");
 
     msg_advance(69);
diff --git a/src/nvim/tag.c b/src/nvim/tag.c
index b9f6494459..796a2fa5f3 100644
--- a/src/nvim/tag.c
+++ b/src/nvim/tag.c
@@ -624,7 +624,7 @@ bool do_tag(char_u *tag, int type, int count, int forceit, int verbose)
           }
           msg_scroll = true;  // Don't overwrite this message.
         } else {
-          give_warning(IObuff, ic);
+          give_warning((char *)IObuff, ic);
         }
         if (ic && !msg_scrolled && msg_silent == 0) {
           ui_flush();
@@ -784,7 +784,7 @@ static void print_tag_list(int new_tag, int use_tagstack, int num_matches, char_
         // print all other extra fields
         attr = HL_ATTR(HLF_CM);
         while (*p && *p != '\r' && *p != '\n') {
-          if (msg_col + ptr2cells(p) >= Columns) {
+          if (msg_col + ptr2cells((char *)p) >= Columns) {
             msg_putchar('\n');
             if (got_int) {
               break;
@@ -830,7 +830,7 @@ static void print_tag_list(int new_tag, int use_tagstack, int num_matches, char_
     }
 
     while (p != command_end) {
-      if (msg_col + (*p == TAB ? 1 : ptr2cells(p)) > Columns) {
+      if (msg_col + (*p == TAB ? 1 : ptr2cells((char *)p)) > Columns) {
         msg_putchar('\n');
       }
       if (got_int) {
@@ -1050,7 +1050,7 @@ void do_tags(exarg_T *eap)
                    tagstack[i].cur_match + 1,
                    tagstack[i].tagname,
                    tagstack[i].fmark.mark.lnum);
-      msg_outtrans(IObuff);
+      msg_outtrans((char *)IObuff);
       msg_outtrans_attr(name, tagstack[i].fmark.fnum == curbuf->b_fnum
                         ? HL_ATTR(HLF_D) : 0);
       xfree(name);
@@ -3032,8 +3032,7 @@ static int test_for_current(char_u *fname, char_u *fname_end, char_u *tag_fname,
       *fname_end = NUL;
     }
     fullname = expand_tag_fname(fname, tag_fname, true);
-    retval = (path_full_compare(fullname, buf_ffname, true, true)
-              & kEqualFiles);
+    retval = (path_full_compare((char *)fullname, (char *)buf_ffname, true, true) & kEqualFiles);
     xfree(fullname);
     *fname_end = (char_u)c;
   }
diff --git a/src/nvim/undo.c b/src/nvim/undo.c
index 684a9cf99e..078cb6a210 100644
--- a/src/nvim/undo.c
+++ b/src/nvim/undo.c
@@ -1468,8 +1468,7 @@ void u_read_undo(char *name, const char_u *hash, const char_u *orig_name FUNC_AT
       if (name == NULL) {
         verbose_enter();
       }
-      give_warning((char_u *)
-                   _("File contents changed, cannot use undo info"), true);
+      give_warning(_("File contents changed, cannot use undo info"), true);
       if (name == NULL) {
         verbose_leave();
       }
diff --git a/src/nvim/version.c b/src/nvim/version.c
index 1c8fdce1eb..a70778fdd9 100644
--- a/src/nvim/version.c
+++ b/src/nvim/version.c
@@ -2020,7 +2020,7 @@ void ex_version(exarg_T *eap)
 /// @param wrap
 static void version_msg_wrap(char *s, int wrap)
 {
-  int len = vim_strsize((char_u *)s) + (wrap ? 2 : 0);
+  int len = vim_strsize(s) + (wrap ? 2 : 0);
 
   if (!got_int
       && (len < Columns)
@@ -2071,7 +2071,7 @@ void list_in_columns(char_u **items, int size, int current)
   // Find the length of the longest item, use that + 1 as the column width.
   int i;
   for (i = 0; size < 0 ? items[i] != NULL : i < size; i++) {
-    int l = vim_strsize(items[i]) + (i == current ? 2 : 0);
+    int l = vim_strsize((char *)items[i]) + (i == current ? 2 : 0);
 
     if (l > width) {
       width = l;
@@ -2294,7 +2294,7 @@ static void do_intro_line(long row, char_u *mesg, int attr)
   int clen;
 
   // Center the message horizontally.
-  col = vim_strsize(mesg);
+  col = vim_strsize((char *)mesg);
 
   col = (Columns - col) / 2;
 
@@ -2309,7 +2309,7 @@ static void do_intro_line(long row, char_u *mesg, int attr)
     for (l = 0;
          p[l] != NUL && (l == 0 || (p[l] != '<' && p[l - 1] != '>'));
          l++) {
-      clen += ptr2cells(p + l);
+      clen += ptr2cells((char *)p + l);
       l += utfc_ptr2len((char *)p + l) - 1;
     }
     assert(row <= INT_MAX && col <= INT_MAX);