From 0344bfad0fc87d2e256ea2b80de7abd069ba1dd2 Mon Sep 17 00:00:00 2001
From: dundargoc <33953936+dundargoc@users.noreply.github.com>
Date: Tue, 17 Jan 2023 14:17:40 +0100
Subject: refactor: replace char_u with char 22 (#21786)

Work on https://github.com/neovim/neovim/issues/459
---
 src/nvim/buffer.c          |  2 +-
 src/nvim/charset.c         | 14 +++----
 src/nvim/cmdexpand.c       | 10 ++---
 src/nvim/cmdhist.c         | 18 ++++-----
 src/nvim/diff.c            |  4 +-
 src/nvim/digraph.c         |  4 +-
 src/nvim/drawline.c        | 38 +++++++++---------
 src/nvim/edit.c            |  4 +-
 src/nvim/eval.c            | 12 +++---
 src/nvim/eval/executor.c   |  2 +-
 src/nvim/eval/funcs.c      | 20 +++++-----
 src/nvim/eval/userfunc.c   | 12 +++---
 src/nvim/eval/vars.c       | 20 +++++-----
 src/nvim/ex_cmds.c         | 14 +++----
 src/nvim/ex_docmd.c        | 56 +++++++++++++--------------
 src/nvim/ex_eval.c         |  7 ++--
 src/nvim/ex_getln.c        | 20 +++++-----
 src/nvim/fileio.c          | 93 ++++++++++++++++++++++----------------------
 src/nvim/fold.c            |  2 +-
 src/nvim/garray.c          |  4 +-
 src/nvim/getchar.c         |  6 +--
 src/nvim/help.c            | 10 ++---
 src/nvim/highlight_group.c |  6 +--
 src/nvim/indent_c.c        |  2 +-
 src/nvim/insexpand.c       | 12 +++---
 src/nvim/lua/spell.c       |  2 +-
 src/nvim/mbyte.c           | 14 +++----
 src/nvim/memline.c         |  4 +-
 src/nvim/mouse.c           | 54 +++++++++++++-------------
 src/nvim/normal.c          |  4 +-
 src/nvim/ops.c             | 78 ++++++++++++++++++-------------------
 src/nvim/option.c          | 24 ++++++------
 src/nvim/optionstr.c       | 10 ++---
 src/nvim/os/env.c          |  4 +-
 src/nvim/os/fs.c           |  7 ++--
 src/nvim/os/shell.c        |  6 +--
 src/nvim/path.c            | 88 +++++++++++++++++++++---------------------
 src/nvim/quickfix.c        | 22 +++++------
 src/nvim/regexp.c          | 14 +++----
 src/nvim/regexp_bt.c       |  6 +--
 src/nvim/regexp_nfa.c      |  4 +-
 src/nvim/screen.c          | 22 +++++------
 src/nvim/search.c          | 56 +++++++++++++--------------
 src/nvim/spell.c           | 94 ++++++++++++++++++++++-----------------------
 src/nvim/spellfile.c       | 96 +++++++++++++++++++++++-----------------------
 src/nvim/spellsuggest.c    | 12 +++---
 src/nvim/statusline.c      |  4 +-
 src/nvim/strings.c         |  4 +-
 src/nvim/syntax.c          |  4 +-
 src/nvim/tag.c             |  4 +-
 src/nvim/testing.c         |  8 ++--
 src/nvim/undo.c            |  4 +-
 src/nvim/usercmd.c         |  2 +-
 src/nvim/window.c          | 24 ++++++------
 54 files changed, 532 insertions(+), 535 deletions(-)

(limited to 'src/nvim')

diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index 3f93d85624..bc0bd9e004 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -3829,7 +3829,7 @@ static int chk_modeline(linenr_T lnum, int flags)
             && (s[0] != 'V'
                 || strncmp(skipwhite(e + 1), "set", 3) == 0)
             && (s[3] == ':'
-                || (VIM_VERSION_100 >= vers && isdigit(s[3]))
+                || (VIM_VERSION_100 >= vers && isdigit((uint8_t)s[3]))
                 || (VIM_VERSION_100 < vers && s[3] == '<')
                 || (VIM_VERSION_100 > vers && s[3] == '>')
                 || (VIM_VERSION_100 == vers && s[3] == '='))) {
diff --git a/src/nvim/charset.c b/src/nvim/charset.c
index aa2d845728..fa9aa27774 100644
--- a/src/nvim/charset.c
+++ b/src/nvim/charset.c
@@ -146,19 +146,19 @@ int buf_init_chartab(buf_T *buf, int global)
   // options Each option is a list of characters, character numbers or
   // ranges, separated by commas, e.g.: "200-210,x,#-178,-"
   for (i = global ? 0 : 3; i <= 3; i++) {
-    const char_u *p;
+    const char *p;
     if (i == 0) {
       // first round: 'isident'
-      p = (char_u *)p_isi;
+      p = p_isi;
     } else if (i == 1) {
       // second round: 'isprint'
-      p = (char_u *)p_isp;
+      p = p_isp;
     } else if (i == 2) {
       // third round: 'isfname'
-      p = (char_u *)p_isf;
+      p = p_isf;
     } else {  // i == 3
       // fourth round: 'iskeyword'
-      p = (char_u *)buf->b_p_isk;
+      p = buf->b_p_isk;
     }
 
     while (*p) {
@@ -254,8 +254,8 @@ int buf_init_chartab(buf_T *buf, int global)
         c++;
       }
 
-      c = *p;
-      p = (char_u *)skip_to_option_part((char *)p);
+      c = (uint8_t)(*p);
+      p = skip_to_option_part(p);
 
       if ((c == ',') && (*p == NUL)) {
         // Trailing comma is not allowed.
diff --git a/src/nvim/cmdexpand.c b/src/nvim/cmdexpand.c
index b5956d75ab..59891e9899 100644
--- a/src/nvim/cmdexpand.c
+++ b/src/nvim/cmdexpand.c
@@ -1174,7 +1174,7 @@ static bool expand_showtail(expand_T *xp)
     // separator, on DOS the '*' "path\*\file" must not be skipped.
     if (rem_backslash(s)) {
       s++;
-    } else if (vim_strchr("*?[", *s) != NULL) {
+    } else if (vim_strchr("*?[", (uint8_t)(*s)) != NULL) {
       return false;
     }
   }
@@ -1405,7 +1405,7 @@ static const char *set_cmd_index(const char *cmd, exarg_T *eap, expand_T *xp, in
       }
     }
     // check for non-alpha command
-    if (p == cmd && vim_strchr("@*!=><&~#", *p) != NULL) {
+    if (p == cmd && vim_strchr("@*!=><&~#", (uint8_t)(*p)) != NULL) {
       p++;
     }
     len = (size_t)(p - cmd);
@@ -1435,7 +1435,7 @@ static const char *set_cmd_index(const char *cmd, exarg_T *eap, expand_T *xp, in
   }
 
   if (eap->cmdidx == CMD_SIZE) {
-    if (*cmd == 's' && vim_strchr("cgriI", cmd[1]) != NULL) {
+    if (*cmd == 's' && vim_strchr("cgriI", (uint8_t)cmd[1]) != NULL) {
       eap->cmdidx = CMD_substitute;
       p = cmd + 1;
     } else if (cmd[0] >= 'A' && cmd[0] <= 'Z') {
@@ -2171,7 +2171,7 @@ static const char *set_one_cmd_context(expand_T *xp, const char *buff)
 
   // 1. skip comment lines and leading space, colons or bars
   const char *cmd;
-  for (cmd = buff; vim_strchr(" \t:|", *cmd) != NULL; cmd++) {}
+  for (cmd = buff; vim_strchr(" \t:|", (uint8_t)(*cmd)) != NULL; cmd++) {}
   xp->xp_pattern = (char *)cmd;
 
   if (*cmd == NUL) {
@@ -2967,7 +2967,7 @@ static void expand_shellcmd(char *filepat, char ***matches, int *numMatches, int
     path = ".";
   } else {
     // For an absolute name we don't use $PATH.
-    if (!path_is_absolute((char_u *)pat)) {
+    if (!path_is_absolute(pat)) {
       path = vim_getenv("PATH");
     }
     if (path == NULL) {
diff --git a/src/nvim/cmdhist.c b/src/nvim/cmdhist.c
index d12ac87bbb..2df82d9355 100644
--- a/src/nvim/cmdhist.c
+++ b/src/nvim/cmdhist.c
@@ -280,7 +280,7 @@ static HistoryType get_histtype(const char *const name, const size_t len, const
     }
   }
 
-  if (vim_strchr(":=@>?/", name[0]) != NULL && len == 1) {
+  if (vim_strchr(":=@>?/", (uint8_t)name[0]) != NULL && len == 1) {
     return hist_char2type(name[0]);
   }
 
@@ -437,7 +437,7 @@ int clr_history(const int histype)
 /// Remove all entries matching {str} from a history.
 ///
 /// @param histype  may be one of the HIST_ values.
-static int del_history_entry(int histype, char_u *str)
+static int del_history_entry(int histype, char *str)
 {
   if (hislen == 0 || histype < 0 || histype >= HIST_COUNT || *str == NUL
       || hisidx[histype] < 0) {
@@ -446,7 +446,7 @@ static int del_history_entry(int histype, char_u *str)
 
   const int idx = hisidx[histype];
   regmatch_T regmatch;
-  regmatch.regprog = vim_regcomp((char *)str, RE_MAGIC + RE_STRING);
+  regmatch.regprog = vim_regcomp(str, RE_MAGIC + RE_STRING);
   if (regmatch.regprog == NULL) {
     return false;
   }
@@ -560,7 +560,7 @@ void f_histdel(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
     // string given: remove all matching entries
     char buf[NUMBUFLEN];
     n = del_history_entry(get_histtype(str, strlen(str), false),
-                          (char_u *)tv_get_string_buf(&argvars[1], buf));
+                          (char *)tv_get_string_buf(&argvars[1], buf));
   }
   rettv->vval.v_number = n;
 }
@@ -611,7 +611,7 @@ void ex_history(exarg_T *eap)
   int idx;
   int i, j, k;
   char *end;
-  char_u *arg = (char_u *)eap->arg;
+  char *arg = eap->arg;
 
   if (hislen == 0) {
     msg(_("'history' option is zero"));
@@ -619,12 +619,12 @@ void ex_history(exarg_T *eap)
   }
 
   if (!(ascii_isdigit(*arg) || *arg == '-' || *arg == ',')) {
-    end = (char *)arg;
+    end = arg;
     while (ASCII_ISALPHA(*end)
-           || vim_strchr(":=@>/?", *end) != NULL) {
+           || vim_strchr(":=@>/?", (uint8_t)(*end)) != NULL) {
       end++;
     }
-    histype1 = get_histtype((const char *)arg, (size_t)(end - (char *)arg), false);
+    histype1 = get_histtype(arg, (size_t)(end - arg), false);
     if (histype1 == HIST_INVALID) {
       if (STRNICMP(arg, "all", end - (char *)arg) == 0) {
         histype1 = 0;
@@ -637,7 +637,7 @@ void ex_history(exarg_T *eap)
       histype2 = histype1;
     }
   } else {
-    end = (char *)arg;
+    end = arg;
   }
   if (!get_list_range(&end, &hisidx1, &hisidx2) || *end != NUL) {
     semsg(_(e_trailing_arg), end);
diff --git a/src/nvim/diff.c b/src/nvim/diff.c
index 45f00cb41e..40be6b1abc 100644
--- a/src/nvim/diff.c
+++ b/src/nvim/diff.c
@@ -1575,7 +1575,7 @@ static bool extract_hunk(FILE *fd, diffhunk_T *hunk, diffstyle_T *diffstyle)
       // --- file1       2018-03-20 13:23:35.783153140 +0100
       // +++ file2       2018-03-20 13:23:41.183156066 +0100
       // @@ -1,3 +1,5 @@
-      if (isdigit(*line)) {
+      if (isdigit((uint8_t)(*line))) {
         *diffstyle = DIFF_ED;
       } else if ((strncmp(line, "@@ ", 3) == 0)) {
         *diffstyle = DIFF_UNIFIED;
@@ -1593,7 +1593,7 @@ static bool extract_hunk(FILE *fd, diffhunk_T *hunk, diffstyle_T *diffstyle)
     }
 
     if (*diffstyle == DIFF_ED) {
-      if (!isdigit(*line)) {
+      if (!isdigit((uint8_t)(*line))) {
         continue;   // not the start of a diff block
       }
       if (parse_diff_ed(line, hunk) == FAIL) {
diff --git a/src/nvim/digraph.c b/src/nvim/digraph.c
index 33038dfb9f..144817fe2b 100644
--- a/src/nvim/digraph.c
+++ b/src/nvim/digraph.c
@@ -1885,7 +1885,7 @@ static int get_digraph_chars(const typval_T *arg, int *char1, int *char2)
 {
   char buf_chars[NUMBUFLEN];
   const char *chars = tv_get_string_buf_chk(arg, buf_chars);
-  const char_u *p = (const char_u *)chars;
+  const char *p = chars;
 
   if (p != NULL) {
     if (*p != NUL) {
@@ -1917,7 +1917,7 @@ static bool digraph_set_common(const typval_T *argchars, const typval_T *argdigr
   if (digraph == NULL) {
     return false;
   }
-  const char_u *p = (const char_u *)digraph;
+  const char *p = digraph;
   int n = mb_cptr2char_adv(&p);
   if (*p != NUL) {
     semsg(_(e_digraph_argument_must_be_one_character_str), digraph);
diff --git a/src/nvim/drawline.c b/src/nvim/drawline.c
index ae3e5698b2..9287fdb460 100644
--- a/src/nvim/drawline.c
+++ b/src/nvim/drawline.c
@@ -513,7 +513,7 @@ static bool use_cursor_line_nr(win_T *wp, linenr_T lnum, int row, int startrow,
                  && (wp->w_p_culopt_flags & CULOPT_LINE)));
 }
 
-static inline void get_line_number_str(win_T *wp, linenr_T lnum, char_u *buf, size_t buf_len)
+static inline void get_line_number_str(win_T *wp, linenr_T lnum, char *buf, size_t buf_len)
 {
   long num;
   char *fmt = "%*ld ";
@@ -531,7 +531,7 @@ static inline void get_line_number_str(win_T *wp, linenr_T lnum, char_u *buf, si
     }
   }
 
-  snprintf((char *)buf, buf_len, fmt, number_width(wp), num);
+  snprintf(buf, buf_len, fmt, number_width(wp), num);
 }
 
 static int get_line_number_attr(win_T *wp, linenr_T lnum, int row, int startrow, int filler_lines)
@@ -612,7 +612,7 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool nochange,
   int row;                            // row in the window, excl w_winrow
   ScreenGrid *grid = &wp->w_grid;     // grid specific to the window
 
-  char_u extra[57];                   // sign, line number and 'fdc' must
+  char extra[57];                     // sign, line number and 'fdc' must
                                       // fit in here
   int n_extra = 0;                    // number of extra chars
   char *p_extra = NULL;               // string of extra chars, plus NUL
@@ -806,7 +806,7 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool nochange,
       nextline[SPWORDLEN] = NUL;
       if (lnum < wp->w_buffer->b_ml.ml_line_count) {
         line = ml_get_buf(wp->w_buffer, lnum + 1, false);
-        spell_cat_line(nextline + SPWORDLEN, (char_u *)line, SPWORDLEN);
+        spell_cat_line(nextline + SPWORDLEN, line, SPWORDLEN);
       }
 
       // When a word wrapped from the previous line the start of the current
@@ -1132,7 +1132,7 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool nochange,
         // no bad word found at line start, don't check until end of a
         // word
         spell_hlf = HLF_COUNT;
-        word_end = (int)(spell_to_word_end((char_u *)ptr, wp) - (char_u *)line + 1);
+        word_end = (int)(spell_to_word_end(ptr, wp) - line + 1);
       } else {
         // bad word found, use attributes until end of word
         assert(len <= INT_MAX);
@@ -1278,7 +1278,7 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool nochange,
         if (wp->w_scwidth > 0) {
           get_sign_display_info(false, wp, lnum, sattrs, row,
                                 startrow, filler_lines, filler_todo,
-                                &c_extra, &c_final, (char *)extra, sizeof(extra),
+                                &c_extra, &c_final, extra, sizeof(extra),
                                 &p_extra, &n_extra, &char_attr, sign_idx,
                                 sign_cul_attr);
           sign_idx++;
@@ -1303,29 +1303,29 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool nochange,
           if (*wp->w_p_scl == 'n' && *(wp->w_p_scl + 1) == 'u' && num_signs > 0) {
             get_sign_display_info(true, wp, lnum, sattrs, row,
                                   startrow, filler_lines, filler_todo,
-                                  &c_extra, &c_final, (char *)extra, sizeof(extra),
+                                  &c_extra, &c_final, extra, sizeof(extra),
                                   &p_extra, &n_extra, &char_attr, sign_idx,
                                   sign_cul_attr);
           } else {
             // Draw the line number (empty space after wrapping).
             if (row == startrow + filler_lines) {
-              get_line_number_str(wp, lnum, (char_u *)extra, sizeof(extra));
+              get_line_number_str(wp, lnum, extra, sizeof(extra));
               if (wp->w_skipcol > 0) {
-                for (p_extra = (char *)extra; *p_extra == ' '; p_extra++) {
+                for (p_extra = extra; *p_extra == ' '; p_extra++) {
                   *p_extra = '-';
                 }
               }
               if (wp->w_p_rl) {                       // reverse line numbers
                 // like rl_mirror(), but keep the space at the end
-                char *p2 = skipwhite((char *)extra);
+                char *p2 = skipwhite(extra);
                 p2 = skiptowhite(p2) - 1;
-                for (char *p1 = skipwhite((char *)extra); p1 < p2; p1++, p2--) {
+                for (char *p1 = skipwhite(extra); p1 < p2; p1++, p2--) {
                   const char t = *p1;
                   *p1 = *p2;
                   *p2 = t;
                 }
               }
-              p_extra = (char *)extra;
+              p_extra = extra;
               c_extra = NUL;
             } else {
               c_extra = ' ';
@@ -1729,14 +1729,14 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool nochange,
           || (mb_l > 1 && (!vim_isprintc(mb_c)))) {
         // Illegal UTF-8 byte: display as <xx>.
         // Non-BMP character : display as ? or fullwidth ?.
-        transchar_hex((char *)extra, mb_c);
+        transchar_hex(extra, mb_c);
         if (wp->w_p_rl) {  // reverse
-          rl_mirror((char *)extra);
+          rl_mirror(extra);
         }
 
-        p_extra = (char *)extra;
+        p_extra = extra;
         c = (uint8_t)(*p_extra);
-        mb_c = mb_ptr2char_adv((const char_u **)&p_extra);
+        mb_c = mb_ptr2char_adv((const char **)&p_extra);
         mb_utf8 = (c >= 0x80);
         n_extra = (int)strlen(p_extra);
         c_extra = NUL;
@@ -1909,7 +1909,7 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool nochange,
               p = prev_ptr;
             }
             cap_col -= (int)(prev_ptr - line);
-            size_t tmplen = spell_check(wp, (char_u *)p, &spell_hlf, &cap_col, nochange);
+            size_t tmplen = spell_check(wp, p, &spell_hlf, &cap_col, nochange);
             assert(tmplen <= INT_MAX);
             len = (int)tmplen;
             word_end = (int)v + len;
@@ -2075,12 +2075,12 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool nochange,
         if (c == TAB && (!wp->w_p_list || wp->w_p_lcs_chars.tab1)) {
           int tab_len = 0;
           long vcol_adjusted = vcol;  // removed showbreak length
-          char_u *const sbr = get_showbreak_value(wp);
+          char *const sbr = (char *)get_showbreak_value(wp);
 
           // Only adjust the tab_len, when at the first column after the
           // showbreak value was drawn.
           if (*sbr != NUL && vcol == vcol_sbr && wp->w_p_wrap) {
-            vcol_adjusted = vcol - mb_charlen((char *)sbr);
+            vcol_adjusted = vcol - mb_charlen(sbr);
           }
           // tab amount depends on current column
           tab_len = tabstop_padding((colnr_T)vcol_adjusted,
diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index 6102f05abd..9b82d50012 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -3127,7 +3127,7 @@ bool in_cinkeys(int keytyped, int when, bool line_is_empty)
         // make up some named keys <o>, <O>, <e>, <0>, <>>, <<>, <*>,
         // <:> and <!> so that people can re-indent on o, O, e, 0, <,
         // >, *, : and ! keys if they really really want to.
-        if (vim_strchr("<>!*oOe0:", look[1]) != NULL
+        if (vim_strchr("<>!*oOe0:", (uint8_t)look[1]) != NULL
             && keytyped == look[1]) {
           return true;
         }
@@ -3182,7 +3182,7 @@ bool in_cinkeys(int keytyped, int when, bool line_is_empty)
           // TODO(@brammool): multi-byte
           if (keytyped == (int)(uint8_t)p[-1]
               || (icase && keytyped < 256
-                  && TOLOWER_LOC(keytyped) == TOLOWER_LOC((int)p[-1]))) {
+                  && TOLOWER_LOC(keytyped) == TOLOWER_LOC((uint8_t)p[-1]))) {
             line = get_cursor_pos_ptr();
             assert(p >= look && (uintmax_t)(p - look) <= SIZE_MAX);
             if ((curwin->w_cursor.col == (colnr_T)(p - look)
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 6d32b71016..b0805aecff 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -2185,7 +2185,7 @@ int pattern_match(const char *pat, const char *text, bool ic)
   regmatch.regprog = vim_regcomp((char *)pat, RE_MAGIC + RE_STRING);
   if (regmatch.regprog != NULL) {
     regmatch.rm_ic = ic;
-    matches = vim_regexec_nl(&regmatch, (char_u *)text, (colnr_T)0);
+    matches = vim_regexec_nl(&regmatch, (char *)text, (colnr_T)0);
     vim_regfree(regmatch.regprog);
   }
   p_cpo = save_cpo;
@@ -2543,7 +2543,7 @@ static int eval4(char **arg, typval_T *rettv, int evaluate)
       if (p[2] == 'n' && p[3] == 'o' && p[4] == 't') {
         len = 5;
       }
-      if (!isalnum(p[len]) && p[len] != '_') {
+      if (!isalnum((uint8_t)p[len]) && p[len] != '_') {
         type = len == 2 ? EXPR_IS : EXPR_ISNOT;
       }
     }
@@ -3777,7 +3777,7 @@ static int get_string_tv(char **arg, typval_T *rettv, int evaluate)
       case 'U':
         if (ascii_isxdigit(p[1])) {
           int n, nr;
-          int c = toupper(*p);
+          int c = toupper((uint8_t)(*p));
 
           if (c == 'X') {
             n = 2;
@@ -6302,7 +6302,7 @@ int get_id_len(const char **const arg)
       // slice "[n:]". Also "xx:" is not a namespace.
       len = (int)(p - *arg);
       if (len > 1
-          || (len == 1 && vim_strchr(namespace_char, **arg) == NULL)) {
+          || (len == 1 && vim_strchr(namespace_char, (uint8_t)(**arg)) == NULL)) {
         break;
       }
     }
@@ -6430,7 +6430,7 @@ const char *find_name_end(const char *arg, const char **expr_start, const char *
       // slice "[n:]".  Also "xx:" is not a namespace. But {ns}: is.
       len = (int)(p - arg);
       if ((len > 1 && p[-1] != '}')
-          || (len == 1 && vim_strchr(namespace_char, *arg) == NULL)) {
+          || (len == 1 && vim_strchr(namespace_char, (uint8_t)(*arg)) == NULL)) {
         break;
       }
     }
@@ -8081,7 +8081,7 @@ char *do_string_sub(char *str, char *pat, char *sub, typval_T *expr, const char
   if (regmatch.regprog != NULL) {
     char *tail = str;
     char *end = str + strlen(str);
-    while (vim_regexec_nl(&regmatch, (char_u *)str, (colnr_T)(tail - str))) {
+    while (vim_regexec_nl(&regmatch, str, (colnr_T)(tail - str))) {
       // Skip empty match except for first match.
       if (regmatch.startp[0] == regmatch.endp[0]) {
         if (zero_width == regmatch.startp[0]) {
diff --git a/src/nvim/eval/executor.c b/src/nvim/eval/executor.c
index 86d6063b01..831c468288 100644
--- a/src/nvim/eval/executor.c
+++ b/src/nvim/eval/executor.c
@@ -69,7 +69,7 @@ int eexe_mod_op(typval_T *const tv1, const typval_T *const tv2, const char *cons
       if (tv2->v_type == VAR_LIST) {
         break;
       }
-      if (vim_strchr("+-*/%", *op) != NULL) {
+      if (vim_strchr("+-*/%", (uint8_t)(*op)) != NULL) {
         // nr += nr  or  nr -= nr, nr *= nr, nr /= nr, nr %= nr
         varnumber_T n = tv_get_number(tv1);
         if (tv2->v_type == VAR_FLOAT) {
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index d6b9ca20fc..25e026706c 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -1770,7 +1770,7 @@ static void f_expand(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
     }
     size_t len;
     char *errormsg = NULL;
-    char *result = (char *)eval_vars((char_u *)s, (char_u *)s, &len, NULL, &errormsg, NULL, false);
+    char *result = (char *)eval_vars((char *)s, (char_u *)s, &len, NULL, &errormsg, NULL, false);
     if (p_verbose == 0) {
       emsg_off--;
     } else if (errormsg != NULL) {
@@ -4488,7 +4488,7 @@ static void find_some_match(typval_T *const argvars, typval_T *const rettv,
         }
       }
 
-      match = vim_regexec_nl(&regmatch, (char_u *)str, startcol);
+      match = vim_regexec_nl(&regmatch, str, startcol);
 
       if (match && --nth <= 0) {
         break;
@@ -5885,7 +5885,7 @@ static void f_resolve(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
           q[-1] = NUL;
           q = path_tail(p);
         }
-        if (q > p && !path_is_absolute((const char_u *)buf)) {
+        if (q > p && !path_is_absolute(buf)) {
           // Symlink is relative to directory of argument. Replace the
           // symlink with the resolved name in the same directory.
           const size_t p_len = strlen(p);
@@ -6228,7 +6228,7 @@ static int search_cmn(typval_T *argvars, pos_T *match_pos, int *flagsp)
   // Repeat until {skip} returns false.
   for (;;) {
     subpatnum
-      = searchit(curwin, curbuf, &pos, NULL, dir, (char_u *)pat, 1, options, RE_SEARCH, &sia);
+      = searchit(curwin, curbuf, &pos, NULL, dir, (char *)pat, 1, options, RE_SEARCH, &sia);
     // finding the first match again means there is no match where {skip}
     // evaluates to zero.
     if (firstpos.lnum != 0 && equalpos(pos, firstpos)) {
@@ -6810,7 +6810,7 @@ long do_searchpair(const char *spat, const char *mpat, const char *epat, int dir
       .sa_tm = &tm,
     };
 
-    int n = searchit(curwin, curbuf, &pos, NULL, dir, (char_u *)pat, 1L,
+    int n = searchit(curwin, curbuf, &pos, NULL, dir, pat, 1L,
                      options, RE_SEARCH, &sia);
     if (n == FAIL || (firstpos.lnum != 0 && equalpos(pos, firstpos))) {
       // didn't find it or found the first match again: FAIL
@@ -7073,7 +7073,7 @@ static void f_setcharsearch(typval_T *argvars, typval_T *rettv, EvalFuncData fpt
   if (csearch != NULL) {
     int pcc[MAX_MCO];
     const int c = utfc_ptr2char((char *)csearch, pcc);
-    set_last_csearch(c, csearch, utfc_ptr2len((char *)csearch));
+    set_last_csearch(c, (char *)csearch, utfc_ptr2len((char *)csearch));
   }
 
   dictitem_T *di = tv_dict_find(d, S_LEN("forward"));
@@ -7553,7 +7553,7 @@ static void f_spellbadword(typval_T *argvars, typval_T *rettv, EvalFuncData fptr
     if (str != NULL) {
       // Check the argument for spelling.
       while (*str != NUL) {
-        len = spell_check(curwin, (char_u *)str, &attr, &capcol, false);
+        len = spell_check(curwin, (char *)str, &attr, &capcol, false);
         if (attr != HLF_COUNT) {
           word = str;
           break;
@@ -7668,7 +7668,7 @@ static void f_split(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
       if (*str == NUL) {
         match = false;  // Empty item at the end.
       } else {
-        match = vim_regexec_nl(&regmatch, (char_u *)str, col);
+        match = vim_regexec_nl(&regmatch, (char *)str, col);
       }
       const char *end;
       if (match) {
@@ -7930,11 +7930,11 @@ static void strchar_common(typval_T *argvars, typval_T *rettv, bool skipcc)
 {
   const char *s = tv_get_string(&argvars[0]);
   varnumber_T len = 0;
-  int (*func_mb_ptr2char_adv)(const char_u **pp);
+  int (*func_mb_ptr2char_adv)(const char **pp);
 
   func_mb_ptr2char_adv = skipcc ? mb_ptr2char_adv : mb_cptr2char_adv;
   while (*s != NUL) {
-    func_mb_ptr2char_adv((const char_u **)&s);
+    func_mb_ptr2char_adv(&s);
     len++;
   }
   rettv->vval.v_number = len;
diff --git a/src/nvim/eval/userfunc.c b/src/nvim/eval/userfunc.c
index 1a3fd13fe3..5d3b70b414 100644
--- a/src/nvim/eval/userfunc.c
+++ b/src/nvim/eval/userfunc.c
@@ -118,7 +118,7 @@ static int get_function_args(char **argp, char_u endchar, garray_T *newargs, int
       while (ASCII_ISALNUM(*p) || *p == '_') {
         p++;
       }
-      if (arg == p || isdigit(*arg)
+      if (arg == p || isdigit((uint8_t)(*arg))
           || (p - arg == 9 && strncmp(arg, "firstline", 9) == 0)
           || (p - arg == 8 && strncmp(arg, "lastline", 8) == 0)) {
         if (!skip) {
@@ -1228,7 +1228,7 @@ void call_user_func(ufunc_T *fp, int argcount, typval_T *argvars, typval_T *rett
 /// looked up by name.
 static bool func_name_refcount(const char_u *name)
 {
-  return isdigit(*name) || *name == '<';
+  return isdigit((uint8_t)(*name)) || *name == '<';
 }
 
 /// Call a user function after checking the arguments.
@@ -2002,7 +2002,7 @@ static void list_functions(regmatch_T *regmatch)
           && (regmatch == NULL
               ? (!message_filtered((char *)fp->uf_name)
                  && !func_name_refcount((char_u *)fp->uf_name))
-              : (!isdigit(*fp->uf_name)
+              : (!isdigit((uint8_t)(*fp->uf_name))
                  && vim_regexec(regmatch, (char *)fp->uf_name, 0)))) {
         list_func_head(fp, false, false);
         if (changed != func_hashtab.ht_changed) {
@@ -2792,7 +2792,7 @@ void ex_delfunction(exarg_T *eap)
     *p = NUL;
   }
 
-  if (isdigit(*name) && fudi.fd_dict == NULL) {
+  if (isdigit((uint8_t)(*name)) && fudi.fd_dict == NULL) {
     if (!eap->skip) {
       semsg(_(e_invarg2), eap->arg);
     }
@@ -2858,7 +2858,7 @@ void func_unref(char_u *name)
   }
 
   fp = find_func(name);
-  if (fp == NULL && isdigit(*name)) {
+  if (fp == NULL && isdigit((uint8_t)(*name))) {
 #ifdef EXITFREE
     if (!entered_free_all_mem) {
       internal_error("func_unref()");
@@ -2901,7 +2901,7 @@ void func_ref(char_u *name)
   fp = find_func(name);
   if (fp != NULL) {
     (fp->uf_refcount)++;
-  } else if (isdigit(*name)) {
+  } else if (isdigit((uint8_t)(*name))) {
     // Only give an error for a numbered function.
     // Fail silently, when named or lambda function isn't found.
     internal_error("func_ref()");
diff --git a/src/nvim/eval/vars.c b/src/nvim/eval/vars.c
index 206df03381..75af99fbd5 100644
--- a/src/nvim/eval/vars.c
+++ b/src/nvim/eval/vars.c
@@ -106,7 +106,7 @@ static list_T *heredoc_get(exarg_T *eap, char *cmd)
       return NULL;
     }
     *p = NUL;
-    if (islower(*marker)) {
+    if (islower((uint8_t)(*marker))) {
       emsg(_("E221: Marker cannot start with lower case letter"));
       return NULL;
     }
@@ -208,7 +208,7 @@ static void ex_let_const(exarg_T *eap, const bool is_const)
     argend--;
   }
   expr = skipwhite(argend);
-  if (*expr != '=' && !((vim_strchr("+-*/%.", *expr) != NULL
+  if (*expr != '=' && !((vim_strchr("+-*/%.", (uint8_t)(*expr)) != NULL
                          && expr[1] == '=') || strncmp(expr, "..=", 3) == 0)) {
     // ":let" without "=": list variables
     if (*arg == '[') {
@@ -244,7 +244,7 @@ static void ex_let_const(exarg_T *eap, const bool is_const)
     op[0] = '=';
     op[1] = NUL;
     if (*expr != '=') {
-      if (vim_strchr("+-*/%.", *expr) != NULL) {
+      if (vim_strchr("+-*/%.", (uint8_t)(*expr)) != NULL) {
         op[0] = *expr;  // +=, -=, *=, /=, %= or .=
         if (expr[0] == '.' && expr[1] == '.') {  // ..=
           expr++;
@@ -590,10 +590,10 @@ static char *ex_let_one(char *arg, typval_T *const tv, const bool copy, const bo
     if (len == 0) {
       semsg(_(e_invarg2), name - 1);
     } else {
-      if (op != NULL && vim_strchr("+-*/%", *op) != NULL) {
+      if (op != NULL && vim_strchr("+-*/%", (uint8_t)(*op)) != NULL) {
         semsg(_(e_letwrong), op);
       } else if (endchars != NULL
-                 && vim_strchr(endchars, *skipwhite(arg)) == NULL) {
+                 && vim_strchr(endchars, (uint8_t)(*skipwhite(arg))) == NULL) {
         emsg(_(e_letunexp));
       } else if (!check_secure()) {
         char *tofree = NULL;
@@ -629,7 +629,7 @@ static char *ex_let_one(char *arg, typval_T *const tv, const bool copy, const bo
     char *const p = (char *)find_option_end((const char **)&arg, &scope);
     if (p == NULL
         || (endchars != NULL
-            && vim_strchr(endchars, *skipwhite(p)) == NULL)) {
+            && vim_strchr(endchars, (uint8_t)(*skipwhite(p))) == NULL)) {
       emsg(_(e_letunexp));
     } else {
       varnumber_T n = 0;
@@ -716,10 +716,10 @@ static char *ex_let_one(char *arg, typval_T *const tv, const bool copy, const bo
       return NULL;
     }
     arg++;
-    if (op != NULL && vim_strchr("+-*/%", *op) != NULL) {
+    if (op != NULL && vim_strchr("+-*/%", (uint8_t)(*op)) != NULL) {
       semsg(_(e_letwrong), op);
     } else if (endchars != NULL
-               && vim_strchr(endchars, *skipwhite(arg + 1)) == NULL) {
+               && vim_strchr(endchars, (uint8_t)(*skipwhite(arg + 1))) == NULL) {
       emsg(_(e_letunexp));
     } else {
       char *s;
@@ -747,7 +747,7 @@ static char *ex_let_one(char *arg, typval_T *const tv, const bool copy, const bo
 
     char *const p = get_lval(arg, tv, &lv, false, false, 0, FNE_CHECK_START);
     if (p != NULL && lv.ll_name != NULL) {
-      if (endchars != NULL && vim_strchr(endchars, *skipwhite(p)) == NULL) {
+      if (endchars != NULL && vim_strchr(endchars, (uint8_t)(*skipwhite(p))) == NULL) {
         emsg(_(e_letunexp));
       } else {
         set_var_lval(&lv, p, tv, copy, is_const, op);
@@ -1464,7 +1464,7 @@ bool var_wrong_func_name(const char *const name, const bool new_var)
 {
   // Allow for w: b: s: and t:.
   // Allow autoload variable.
-  if (!(vim_strchr("wbst", name[0]) != NULL && name[1] == ':')
+  if (!(vim_strchr("wbst", (uint8_t)name[0]) != NULL && name[1] == ':')
       && !ASCII_ISUPPER((name[0] != NUL && name[1] == ':') ? name[2] : name[0])
       && vim_strchr(name, '#') == NULL) {
     semsg(_("E704: Funcref variable name must start with a capital: %s"), name);
diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index c2af0e6986..4ea11dd32a 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -528,7 +528,7 @@ void ex_sort(exarg_T *eap)
           emsg(_(e_noprevre));
           goto sortend;
         }
-        regmatch.regprog = vim_regcomp((char *)last_search_pat(), RE_MAGIC);
+        regmatch.regprog = vim_regcomp(last_search_pat(), RE_MAGIC);
       } else {
         regmatch.regprog = vim_regcomp(p + 1, RE_MAGIC);
       }
@@ -3332,7 +3332,7 @@ static int do_sub(exarg_T *eap, proftime_T timeout, long cmdpreview_ns, handle_T
   }
   // new pattern and substitution
   if (eap->cmd[0] == 's' && *cmd != NUL && !ascii_iswhite(*cmd)
-      && vim_strchr("0123456789cegriIp|\"", *cmd) == NULL) {
+      && vim_strchr("0123456789cegriIp|\"", (uint8_t)(*cmd)) == NULL) {
     // don't accept alphanumeric for separator
     if (check_regexp_delim(*cmd) == FAIL) {
       return 0;
@@ -3343,7 +3343,7 @@ static int do_sub(exarg_T *eap, proftime_T timeout, long cmdpreview_ns, handle_T
     //  //sub/r).  "\&sub&" use last substitute pattern (like //sub/).
     if (*cmd == '\\') {
       cmd++;
-      if (vim_strchr("/?&", *cmd) == NULL) {
+      if (vim_strchr("/?&", (uint8_t)(*cmd)) == NULL) {
         emsg(_(e_backslash));
         return 0;
       }
@@ -3443,7 +3443,7 @@ static int do_sub(exarg_T *eap, proftime_T timeout, long cmdpreview_ns, handle_T
     return 0;
   }
 
-  if (search_regcomp((char_u *)pat, NULL, RE_SUBST, which_pat,
+  if (search_regcomp(pat, NULL, RE_SUBST, which_pat,
                      (cmdpreview ? 0 : SEARCH_HIS), &regmatch) == FAIL) {
     if (subflags.do_error) {
       emsg(_(e_invcmd));
@@ -4372,7 +4372,7 @@ void ex_global(exarg_T *eap)
   //             "\&": use previous substitute pattern.
   if (*cmd == '\\') {
     cmd++;
-    if (vim_strchr("/?&", *cmd) == NULL) {
+    if (vim_strchr("/?&", (uint8_t)(*cmd)) == NULL) {
       emsg(_(e_backslash));
       return;
     }
@@ -4398,8 +4398,8 @@ void ex_global(exarg_T *eap)
     }
   }
 
-  char_u *used_pat;
-  if (search_regcomp((char_u *)pat, &used_pat, RE_BOTH, which_pat,
+  char *used_pat;
+  if (search_regcomp(pat, &used_pat, RE_BOTH, which_pat,
                      SEARCH_HIS, &regmatch) == FAIL) {
     emsg(_(e_invcmd));
     return;
diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index 511251f0b5..896130debf 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -2852,7 +2852,7 @@ bool checkforcmd(char **pp, const char *cmd, int len)
       break;
     }
   }
-  if (i >= len && !isalpha((*pp)[i])) {
+  if (i >= len && !isalpha((uint8_t)(*pp)[i])) {
     *pp = skipwhite(*pp + i);
     return true;
   }
@@ -2877,7 +2877,7 @@ static void append_command(char *cmd)
   STRCAT(IObuff, ": ");
   d = IObuff + strlen(IObuff);
   while (*s != NUL && d - IObuff + 5 < IOSIZE) {
-    if ((char_u)s[0] == 0xc2 && (char_u)s[1] == 0xa0) {
+    if ((uint8_t)s[0] == 0xc2 && (uint8_t)s[1] == 0xa0) {
       s += 2;
       STRCPY(d, "<a0>");
       d += 4;
@@ -2942,7 +2942,7 @@ char *find_ex_command(exarg_T *eap, int *full)
     }
 
     // check for non-alpha command
-    if (p == eap->cmd && vim_strchr("@!=><&~#", *p) != NULL) {
+    if (p == eap->cmd && vim_strchr("@!=><&~#", (uint8_t)(*p)) != NULL) {
       p++;
     }
     int len = (int)(p - eap->cmd);
@@ -2967,7 +2967,7 @@ char *find_ex_command(exarg_T *eap, int *full)
     }
 
     if (ASCII_ISLOWER(eap->cmd[0])) {
-      const int c1 = (char_u)eap->cmd[0];
+      const int c1 = (uint8_t)eap->cmd[0];
       const int c2 = len == 1 ? NUL : eap->cmd[1];
 
       if (command_count != CMD_SIZE) {
@@ -3172,7 +3172,7 @@ uint32_t excmd_get_argt(cmdidx_T idx)
 /// @return the "cmd" pointer advanced to beyond the range.
 char *skip_range(const char *cmd, int *ctx)
 {
-  while (vim_strchr(" \t0123456789.$%'/?-+,;\\", *cmd) != NULL) {
+  while (vim_strchr(" \t0123456789.$%'/?-+,;\\", (uint8_t)(*cmd)) != NULL) {
     if (*cmd == '\\') {
       if (cmd[1] == '?' || cmd[1] == '/' || cmd[1] == '&') {
         cmd++;
@@ -3361,7 +3361,7 @@ static linenr_T get_address(exarg_T *eap, char **ptr, cmd_addr_T addr_type, int
 
     case '/':
     case '?':                           // '/' or '?' - search
-      c = (char_u)(*cmd++);
+      c = (uint8_t)(*cmd++);
       if (addr_type != ADDR_LINES) {
         addr_error(addr_type);
         cmd = NULL;
@@ -3434,7 +3434,7 @@ static linenr_T get_address(exarg_T *eap, char **ptr, cmd_addr_T addr_type, int
         pos.coladd = 0;
         if (searchit(curwin, curbuf, &pos, NULL,
                      *cmd == '?' ? BACKWARD : FORWARD,
-                     (char_u *)"", 1L, SEARCH_MSG, i, NULL) != FAIL) {
+                     "", 1L, SEARCH_MSG, i, NULL) != FAIL) {
           lnum = pos.lnum;
         } else {
           cmd = NULL;
@@ -3495,7 +3495,7 @@ static linenr_T get_address(exarg_T *eap, char **ptr, cmd_addr_T addr_type, int
       if (ascii_isdigit(*cmd)) {
         i = '+';                        // "number" is same as "+number"
       } else {
-        i = (char_u)(*cmd++);
+        i = (uint8_t)(*cmd++);
       }
       if (!ascii_isdigit(*cmd)) {       // '+' is '+1'
         n = 1;
@@ -3542,7 +3542,7 @@ error:
 /// Get flags from an Ex command argument.
 static void get_flags(exarg_T *eap)
 {
-  while (vim_strchr("lp#", *eap->arg) != NULL) {
+  while (vim_strchr("lp#", (uint8_t)(*eap->arg)) != NULL) {
     if (*eap->arg == 'l') {
       eap->flags |= EXFLAG_LIST;
     } else if (*eap->arg == 'p') {
@@ -3759,7 +3759,7 @@ int expand_filename(exarg_T *eap, char **cmdlinep, char **errormsgp)
     }
     // Quick check if this cannot be the start of a special string.
     // Also removes backslash before '%', '#' and '<'.
-    if (vim_strchr("%#<", *p) == NULL) {
+    if (vim_strchr("%#<", (uint8_t)(*p)) == NULL) {
       p++;
       continue;
     }
@@ -3767,7 +3767,7 @@ int expand_filename(exarg_T *eap, char **cmdlinep, char **errormsgp)
     // Try to find a match at this position.
     size_t srclen;
     int escaped;
-    char *repl = (char *)eval_vars((char_u *)p, (char_u *)eap->arg, &srclen, &(eap->do_ecmd_lnum),
+    char *repl = (char *)eval_vars(p, (char_u *)eap->arg, &srclen, &(eap->do_ecmd_lnum),
                                    errormsgp, &escaped, true);
     if (*errormsgp != NULL) {           // error detected
       return FAIL;
@@ -3812,7 +3812,7 @@ int expand_filename(exarg_T *eap, char **cmdlinep, char **errormsgp)
 #endif
 
       for (l = repl; *l; l++) {
-        if (vim_strchr((char *)ESCAPE_CHARS, *l) != NULL) {
+        if (vim_strchr((char *)ESCAPE_CHARS, (uint8_t)(*l)) != NULL) {
           l = vim_strsave_escaped(repl, (char *)ESCAPE_CHARS);
           xfree(repl);
           repl = l;
@@ -4044,15 +4044,15 @@ char *skip_cmd_arg(char *p, int rembs)
   return p;
 }
 
-int get_bad_opt(const char_u *p, exarg_T *eap)
+int get_bad_opt(const char *p, exarg_T *eap)
   FUNC_ATTR_NONNULL_ALL
 {
   if (STRICMP(p, "keep") == 0) {
     eap->bad_char = BAD_KEEP;
   } else if (STRICMP(p, "drop") == 0) {
     eap->bad_char = BAD_DROP;
-  } else if (MB_BYTE2LEN(*p) == 1 && p[1] == NUL) {
-    eap->bad_char = *p;
+  } else if (MB_BYTE2LEN((uint8_t)(*p)) == 1 && p[1] == NUL) {
+    eap->bad_char = (uint8_t)(*p);
   } else {
     return FAIL;
   }
@@ -4129,7 +4129,7 @@ static int getargopt(exarg_T *eap)
     if (check_ff_value(eap->cmd + eap->force_ff) == FAIL) {
       return FAIL;
     }
-    eap->force_ff = (char_u)eap->cmd[eap->force_ff];
+    eap->force_ff = (uint8_t)eap->cmd[eap->force_ff];
   } else if (pp == &eap->force_enc) {
     // Make 'fileencoding' lower case.
     for (char *p = eap->cmd + eap->force_enc; *p != NUL; p++) {
@@ -4138,7 +4138,7 @@ static int getargopt(exarg_T *eap)
   } else {
     // Check ++bad= argument.  Must be a single-byte character, "keep" or
     // "drop".
-    if (get_bad_opt((char_u *)eap->cmd + bad_char_idx, eap) == FAIL) {
+    if (get_bad_opt(eap->cmd + bad_char_idx, eap) == FAIL) {
       return FAIL;
     }
   }
@@ -6002,7 +6002,7 @@ static void ex_later(exarg_T *eap)
 
   if (*p == NUL) {
     count = 1;
-  } else if (isdigit(*p)) {
+  } else if (isdigit((uint8_t)(*p))) {
     count = getdigits_long(&p, false, 0);
     switch (*p) {
     case 's':
@@ -6060,7 +6060,7 @@ static void ex_redir(exarg_T *eap)
       close_redir();
       arg++;
       if (valid_yank_reg(*arg, true) && *arg != '_') {
-        redir_reg = (char_u)(*arg++);
+        redir_reg = (uint8_t)(*arg++);
         if (*arg == '>' && arg[1] == '>') {        // append
           arg += 2;
         } else {
@@ -6725,7 +6725,7 @@ ssize_t find_cmdline_var(const char *src, size_t *usedlen)
 /// @return          an allocated string if a valid match was found.
 ///                  Returns NULL if no match was found.  "usedlen" then still contains the
 ///                  number of characters to skip.
-char_u *eval_vars(char_u *src, const char_u *srcstart, size_t *usedlen, linenr_T *lnump,
+char_u *eval_vars(char *src, const char_u *srcstart, size_t *usedlen, linenr_T *lnump,
                   char **errormsg, int *escaped, bool empty_is_error)
 {
   char *result;
@@ -6742,7 +6742,7 @@ char_u *eval_vars(char_u *src, const char_u *srcstart, size_t *usedlen, linenr_T
   }
 
   // Check if there is something to do.
-  ssize_t spec_idx = find_cmdline_var((char *)src, usedlen);
+  ssize_t spec_idx = find_cmdline_var(src, usedlen);
   if (spec_idx < 0) {   // no match
     *usedlen = 1;
     return NULL;
@@ -6750,7 +6750,7 @@ char_u *eval_vars(char_u *src, const char_u *srcstart, size_t *usedlen, linenr_T
 
   // Skip when preceded with a backslash "\%" and "\#".
   // Note: In "\\%" the % is also not recognized!
-  if (src > srcstart && src[-1] == '\\') {
+  if ((char_u *)src > srcstart && src[-1] == '\\') {
     *usedlen = 0;
     STRMOVE(src - 1, (char *)src);      // remove backslash
     return NULL;
@@ -6800,16 +6800,16 @@ char_u *eval_vars(char_u *src, const char_u *srcstart, size_t *usedlen, linenr_T
         skip_mod = true;
         break;
       }
-      char *s = (char *)src + 1;
+      char *s = src + 1;
       if (*s == '<') {                  // "#<99" uses v:oldfiles.
         s++;
       }
       int i = getdigits_int(&s, false, 0);
-      if ((char_u *)s == src + 2 && src[1] == '-') {
+      if (s == src + 2 && src[1] == '-') {
         // just a minus sign, don't skip over it
         s--;
       }
-      *usedlen = (size_t)((char_u *)s - src);           // length of what we expand
+      *usedlen = (size_t)(s - src);           // length of what we expand
 
       if (src[1] == '<' && i != 0) {
         if (*usedlen < 2) {
@@ -6855,7 +6855,7 @@ char_u *eval_vars(char_u *src, const char_u *srcstart, size_t *usedlen, linenr_T
 
     case SPEC_AFILE:  // file name for autocommand
       if (autocmd_fname != NULL
-          && !path_is_absolute((char_u *)autocmd_fname)
+          && !path_is_absolute(autocmd_fname)
           // For CmdlineEnter and related events, <afile> is not a path! #9348
           && !strequal("/", autocmd_fname)) {
         // Still need to turn the fname into a full path.  It was
@@ -6962,7 +6962,7 @@ char_u *eval_vars(char_u *src, const char_u *srcstart, size_t *usedlen, linenr_T
         resultlen = (size_t)(s - result);
       }
     } else if (!skip_mod) {
-      valid |= modify_fname((char *)src, tilde_file, usedlen, &result,
+      valid |= modify_fname(src, tilde_file, usedlen, &result,
                             &resultbuf, &resultlen);
       if (result == NULL) {
         *errormsg = "";
@@ -7002,7 +7002,7 @@ char *expand_sfile(char *arg)
       // replace "<sfile>" with the sourced file name, and do ":" stuff
       size_t srclen;
       char *errormsg;
-      char *repl = (char *)eval_vars((char_u *)p, (char_u *)result, &srclen, NULL, &errormsg, NULL,
+      char *repl = (char *)eval_vars(p, (char_u *)result, &srclen, NULL, &errormsg, NULL,
                                      true);
       if (errormsg != NULL) {
         if (*errormsg) {
diff --git a/src/nvim/ex_eval.c b/src/nvim/ex_eval.c
index 6450892e39..bfbb6f89b5 100644
--- a/src/nvim/ex_eval.c
+++ b/src/nvim/ex_eval.c
@@ -449,8 +449,8 @@ static int throw_exception(void *value, except_type_T type, char *cmdname)
   // when no active try block is found, see do_cmdline().
   if (type == ET_USER) {
     if (strncmp(value, "Vim", 3) == 0
-        && (((char_u *)value)[3] == NUL || ((char_u *)value)[3] == ':'
-            || ((char_u *)value)[3] == '(')) {
+        && (((char *)value)[3] == NUL || ((char *)value)[3] == ':'
+            || ((char *)value)[3] == '(')) {
       emsg(_("E608: Cannot :throw exceptions with 'Vim' prefix"));
       goto fail;
     }
@@ -1372,8 +1372,7 @@ void ex_catch(exarg_T *eap)
           //
           prev_got_int = got_int;
           got_int = false;
-          caught = vim_regexec_nl(&regmatch, (char_u *)current_exception->value,
-                                  (colnr_T)0);
+          caught = vim_regexec_nl(&regmatch, current_exception->value, (colnr_T)0);
           got_int |= prev_got_int;
           vim_regfree(regmatch.regprog);
         }
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index 47ee1c00ce..0a1d6b2857 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -274,7 +274,7 @@ static bool do_incsearch_highlighting(int firstc, int *search_delim, incsearch_s
   parse_command_modifiers(&ea, &dummy, &dummy_cmdmod, true);
 
   cmd = skip_range(ea.cmd, NULL);
-  if (vim_strchr("sgvl", *cmd) == NULL) {
+  if (vim_strchr("sgvl", (uint8_t)(*cmd)) == NULL) {
     goto theend;
   }
 
@@ -558,7 +558,7 @@ static int may_add_char_to_search(int firstc, int *c, incsearch_state_T *s)
       // command line has no uppercase characters, convert
       // the character to lowercase
       if (p_ic && p_scs
-          && !pat_has_uppercase((char_u *)ccline.cmdbuff + skiplen)) {
+          && !pat_has_uppercase(ccline.cmdbuff + skiplen)) {
         *c = mb_tolower(*c);
       }
       if (*c == search_delim
@@ -1379,7 +1379,7 @@ static int may_do_command_line_next_incsearch(int firstc, long count, incsearch_
   char save;
 
   if (search_delim == ccline.cmdbuff[skiplen]) {
-    pat = (char *)last_search_pattern();
+    pat = last_search_pattern();
     if (pat == NULL) {
       restore_last_search_pattern();
       return FAIL;
@@ -1409,7 +1409,7 @@ static int may_do_command_line_next_incsearch(int firstc, long count, incsearch_
   pat[patlen] = NUL;
   int found = searchit(curwin, curbuf, &t, NULL,
                        next_match ? FORWARD : BACKWARD,
-                       (char_u *)pat, count, search_flags,
+                       pat, count, search_flags,
                        RE_SEARCH, NULL);
   emsg_off--;
   pat[patlen] = save;
@@ -2165,7 +2165,7 @@ static bool empty_pattern_magic(char *p, size_t len, magic_T magic_val)
 {
   // remove trailing \v and the like
   while (len >= 2 && p[len - 2] == '\\'
-         && vim_strchr("mMvVcCZ", p[len - 1]) != NULL) {
+         && vim_strchr("mMvVcCZ", (uint8_t)p[len - 1]) != NULL) {
     len -= 2;
   }
 
@@ -3733,7 +3733,7 @@ static bool cmdline_paste(int regname, bool literally, bool remcr)
       }
     }
 
-    cmdline_paste_str(p, literally);
+    cmdline_paste_str((char *)p, literally);
     if (allocated) {
       xfree(arg);
     }
@@ -3747,19 +3747,19 @@ static bool cmdline_paste(int regname, bool literally, bool remcr)
 // When "literally" is true, insert literally.
 // When "literally" is false, insert as typed, but don't leave the command
 // line.
-void cmdline_paste_str(char_u *s, int literally)
+void cmdline_paste_str(char *s, int literally)
 {
   int c, cv;
 
   if (literally) {
-    put_on_cmdline((char *)s, -1, true);
+    put_on_cmdline(s, -1, true);
   } else {
     while (*s != NUL) {
-      cv = *s;
+      cv = (uint8_t)(*s);
       if (cv == Ctrl_V && s[1]) {
         s++;
       }
-      c = mb_cptr2char_adv((const char_u **)&s);
+      c = mb_cptr2char_adv((const char **)&s);
       if (cv == Ctrl_V || c == ESC || c == Ctrl_C
           || c == CAR || c == NL || c == Ctrl_L
           || (c == Ctrl_BSL && *s == Ctrl_N)) {
diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index 0ee547d124..3a7db22d2f 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -278,7 +278,7 @@ int readfile(char *fname, char *sfname, linenr_T from, linenr_T lines_to_skip,
       && fname != NULL
       && vim_strchr(p_cpo, CPO_FNAMER) != NULL
       && !(flags & READ_DUMMY)) {
-    if (set_rw_fname((char_u *)fname, (char_u *)sfname) == FAIL) {
+    if (set_rw_fname(fname, sfname) == FAIL) {
       return FAIL;
     }
   }
@@ -860,7 +860,7 @@ retry:
       // Skip conversion when it's already done (retry for wrong
       // "fileformat").
       if (tmpname == NULL) {
-        tmpname = (char *)readfile_charconvert((char_u *)fname, (char_u *)fenc, &fd);
+        tmpname = readfile_charconvert(fname, fenc, &fd);
         if (tmpname == NULL) {
           // Conversion failed.  Try another one.
           advance_fenc = true;
@@ -1175,7 +1175,7 @@ retry:
             goto rewind_retry;
           }
           if (conv_error == 0) {
-            conv_error = readfile_linenr(linecnt, (char_u *)ptr, (char_u *)top);
+            conv_error = readfile_linenr(linecnt, ptr, top);
           }
 
           // Deal with a bad byte and continue with the next.
@@ -1287,7 +1287,7 @@ retry:
                   goto rewind_retry;
                 }
                 if (conv_error == 0) {
-                  conv_error = readfile_linenr(linecnt, (char_u *)ptr, p);
+                  conv_error = readfile_linenr(linecnt, ptr, (char *)p);
                 }
                 if (bad_char_behavior == BAD_DROP) {
                   continue;
@@ -1315,7 +1315,7 @@ retry:
                   goto rewind_retry;
                 }
                 if (conv_error == 0) {
-                  conv_error = readfile_linenr(linecnt, (char_u *)ptr, p);
+                  conv_error = readfile_linenr(linecnt, ptr, (char *)p);
                 }
                 if (bad_char_behavior == BAD_DROP) {
                   continue;
@@ -1356,7 +1356,7 @@ retry:
                   goto rewind_retry;
                 }
                 if (conv_error == 0) {
-                  conv_error = readfile_linenr(linecnt, (char_u *)ptr, p);
+                  conv_error = readfile_linenr(linecnt, ptr, (char *)p);
                 }
                 if (bad_char_behavior == BAD_DROP) {
                   continue;
@@ -1423,12 +1423,12 @@ retry:
 #ifdef HAVE_ICONV
               // When we did a conversion report an error.
               if (iconv_fd != (iconv_t)-1 && conv_error == 0) {
-                conv_error = readfile_linenr(linecnt, (char_u *)ptr, p);
+                conv_error = readfile_linenr(linecnt, ptr, (char *)p);
               }
 #endif
               // Remember the first linenr with an illegal byte
               if (conv_error == 0 && illegal_byte == 0) {
-                illegal_byte = readfile_linenr(linecnt, (char_u *)ptr, p);
+                illegal_byte = readfile_linenr(linecnt, ptr, (char *)p);
               }
 
               // Drop, keep or replace the bad byte.
@@ -1887,7 +1887,7 @@ failed:
     char_u hash[UNDO_HASH_SIZE];
 
     sha256_finish(&sha_ctx, hash);
-    u_read_undo(NULL, hash, (char_u *)fname);
+    u_read_undo(NULL, hash, fname);
   }
 
   if (!read_stdin && !read_fifo && (!read_buffer || sfname != NULL)) {
@@ -1958,9 +1958,9 @@ bool is_dev_fd_file(char *fname)
 /// @param linecnt  line count before reading more bytes
 /// @param p        start of more bytes read
 /// @param endp     end of more bytes read
-static linenr_T readfile_linenr(linenr_T linecnt, char_u *p, const char_u *endp)
+static linenr_T readfile_linenr(linenr_T linecnt, char *p, const char *endp)
 {
-  char_u *s;
+  char *s;
   linenr_T lnum;
 
   lnum = curbuf->b_ml.ml_line_count - linecnt + 1;
@@ -2040,7 +2040,7 @@ static char *next_fenc(char **pp, bool *alloced)
     *pp = NULL;
     return "";
   }
-  p = vim_strchr((*pp), ',');
+  p = vim_strchr(*pp, ',');
   if (p == NULL) {
     r = enc_canonize(*pp);
     *pp += strlen(*pp);
@@ -2065,22 +2065,22 @@ static char *next_fenc(char **pp, bool *alloced)
 ///
 /// @return       name of the resulting converted file (the caller should delete it after reading it).
 ///               Returns NULL if the conversion failed ("*fdp" is not set) .
-static char_u *readfile_charconvert(char_u *fname, char_u *fenc, int *fdp)
+static char *readfile_charconvert(char *fname, char *fenc, int *fdp)
 {
-  char_u *tmpname;
+  char *tmpname;
   char *errmsg = NULL;
 
-  tmpname = (char_u *)vim_tempname();
+  tmpname = vim_tempname();
   if (tmpname == NULL) {
     errmsg = _("Can't find temp file for conversion");
   } else {
     close(*fdp);                // close the input file, ignore errors
     *fdp = -1;
-    if (eval_charconvert((char *)fenc, "utf-8",
-                         (char *)fname, (char *)tmpname) == FAIL) {
+    if (eval_charconvert(fenc, "utf-8",
+                         fname, tmpname) == FAIL) {
       errmsg = _("Conversion with 'charconvert' failed");
     }
-    if (errmsg == NULL && (*fdp = os_open((char *)tmpname, O_RDONLY, 0)) < 0) {
+    if (errmsg == NULL && (*fdp = os_open(tmpname, O_RDONLY, 0)) < 0) {
       errmsg = _("can't read output of 'charconvert'");
     }
   }
@@ -2090,14 +2090,14 @@ static char_u *readfile_charconvert(char_u *fname, char_u *fenc, int *fdp)
     // another type of conversion might still work.
     msg(errmsg);
     if (tmpname != NULL) {
-      os_remove((char *)tmpname);  // delete converted file
+      os_remove(tmpname);  // delete converted file
       XFREE_CLEAR(tmpname);
     }
   }
 
   // If the input file is closed, open it (caller should check for error).
   if (*fdp < 0) {
-    *fdp = os_open((char *)fname, O_RDONLY, 0);
+    *fdp = os_open(fname, O_RDONLY, 0);
   }
 
   return tmpname;
@@ -2254,7 +2254,7 @@ int buf_write(buf_T *buf, char *fname, char *sfname, linenr_T start, linenr_T en
       && !filtering
       && (!append || vim_strchr(p_cpo, CPO_FNAMEAPP) != NULL)
       && vim_strchr(p_cpo, CPO_FNAMEW) != NULL) {
-    if (set_rw_fname((char_u *)fname, (char_u *)sfname) == FAIL) {
+    if (set_rw_fname(fname, sfname) == FAIL) {
       return FAIL;
     }
     buf = curbuf;           // just in case autocmds made "buf" invalid
@@ -2572,7 +2572,7 @@ int buf_write(buf_T *buf, char *fname, char *sfname, linenr_T start, linenr_T en
 
   // If 'backupskip' is not empty, don't make a backup for some files.
   dobackup = (p_wb || p_bk || *p_pm != NUL);
-  if (dobackup && *p_bsk != NUL && match_file_list(p_bsk, (char_u *)sfname, (char_u *)ffname)) {
+  if (dobackup && *p_bsk != NUL && match_file_list((char *)p_bsk, sfname, ffname)) {
     dobackup = false;
   }
 
@@ -3652,7 +3652,7 @@ nofail:
 
 /// Set the name of the current buffer.  Use when the buffer doesn't have a
 /// name and a ":r" or ":w" command with a file name is used.
-static int set_rw_fname(char_u *fname, char_u *sfname)
+static int set_rw_fname(char *fname, char *sfname)
 {
   buf_T *buf = curbuf;
 
@@ -3670,7 +3670,7 @@ static int set_rw_fname(char_u *fname, char_u *sfname)
     return FAIL;
   }
 
-  if (setfname(curbuf, (char *)fname, (char *)sfname, false) == OK) {
+  if (setfname(curbuf, fname, sfname, false) == OK) {
     curbuf->b_flags |= BF_NOTEDITED;
   }
 
@@ -4205,7 +4205,7 @@ static int make_bom(char_u *buf, char_u *name)
 ///
 /// For buffers that have buftype "nofile" or "scratch": never change the file
 /// name.
-void shorten_buf_fname(buf_T *buf, char_u *dirname, int force)
+void shorten_buf_fname(buf_T *buf, char *dirname, int force)
 {
   char *p;
 
@@ -4214,11 +4214,11 @@ void shorten_buf_fname(buf_T *buf, char_u *dirname, int force)
       && !path_with_url(buf->b_fname)
       && (force
           || buf->b_sfname == NULL
-          || path_is_absolute((char_u *)buf->b_sfname))) {
+          || path_is_absolute(buf->b_sfname))) {
     if (buf->b_sfname != buf->b_ffname) {
       XFREE_CLEAR(buf->b_sfname);
     }
-    p = path_shorten_fname(buf->b_ffname, (char *)dirname);
+    p = path_shorten_fname(buf->b_ffname, dirname);
     if (p != NULL) {
       buf->b_sfname = xstrdup(p);
       buf->b_fname = buf->b_sfname;
@@ -4236,7 +4236,7 @@ void shorten_fnames(int force)
 
   os_dirname((char *)dirname, MAXPATHL);
   FOR_ALL_BUFFERS(buf) {
-    shorten_buf_fname(buf, dirname, force);
+    shorten_buf_fname(buf, (char *)dirname, force);
 
     // Always make the swap file name a full path, a "nofile" buffer may
     // also have a swap file.
@@ -4552,7 +4552,7 @@ int vim_rename(const char *from, const char *to)
   }
 
   if (use_tmp_file) {
-    char_u tempname[MAXPATHL + 1];
+    char tempname[MAXPATHL + 1];
 
     // Find a name that doesn't exist and is in the same directory.
     // Rename "from" to "tempname" and then rename "tempname" to "to".
@@ -4561,17 +4561,17 @@ int vim_rename(const char *from, const char *to)
     }
     STRCPY(tempname, from);
     for (n = 123; n < 99999; n++) {
-      char *tail = path_tail((char *)tempname);
-      snprintf(tail, (size_t)((MAXPATHL + 1) - (tail - (char *)tempname - 1)), "%d", n);
+      char *tail = path_tail(tempname);
+      snprintf(tail, (size_t)((MAXPATHL + 1) - (tail - tempname - 1)), "%d", n);
 
-      if (!os_path_exists((char *)tempname)) {
-        if (os_rename((char_u *)from, tempname) == OK) {
-          if (os_rename(tempname, (char_u *)to) == OK) {
+      if (!os_path_exists(tempname)) {
+        if (os_rename(from, tempname) == OK) {
+          if (os_rename(tempname, to) == OK) {
             return 0;
           }
           // Strange, the second step failed.  Try moving the
           // file back and return failure.
-          (void)os_rename(tempname, (char_u *)from);
+          (void)os_rename(tempname, from);
           return -1;
         }
         // If it fails for one temp name it will most likely fail
@@ -4589,7 +4589,7 @@ int vim_rename(const char *from, const char *to)
   os_remove((char *)to);
 
   // First try a normal rename, return if it works.
-  if (os_rename((char_u *)from, (char_u *)to) == OK) {
+  if (os_rename(from, to) == OK) {
     return 0;
   }
 
@@ -5317,7 +5317,7 @@ int delete_recursive(const char *name)
     garray_T ga;
     if (readdir_core(&ga, exp, NULL, NULL) == OK) {
       for (int i = 0; i < ga.ga_len; i++) {
-        vim_snprintf(NameBuff, MAXPATHL, "%s/%s", exp, ((char_u **)ga.ga_data)[i]);
+        vim_snprintf(NameBuff, MAXPATHL, "%s/%s", exp, ((char **)ga.ga_data)[i]);
         if (delete_recursive((const char *)NameBuff) != 0) {
           // Remember the failure but continue deleting any further
           // entries.
@@ -5505,28 +5505,27 @@ bool match_file_pat(char *pattern, regprog_T **prog, char *fname, char *sfname,
 /// @param ffname full file name
 ///
 /// @return true if there was a match
-bool match_file_list(char_u *list, char_u *sfname, char_u *ffname)
+bool match_file_list(char *list, char *sfname, char *ffname)
   FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ARG(1, 3)
 {
-  char_u buf[100];
-  char_u *tail;
-  char_u *regpat;
+  char buf[100];
+  char *tail;
+  char *regpat;
   char allow_dirs;
   bool match;
   char *p;
 
-  tail = (char_u *)path_tail((char *)sfname);
+  tail = path_tail(sfname);
 
   // try all patterns in 'wildignore'
-  p = (char *)list;
+  p = list;
   while (*p) {
-    copy_option_part(&p, (char *)buf, ARRAY_SIZE(buf), ",");
-    regpat = (char_u *)file_pat_to_reg_pat((char *)buf, NULL, &allow_dirs, false);
+    copy_option_part(&p, buf, ARRAY_SIZE(buf), ",");
+    regpat = file_pat_to_reg_pat(buf, NULL, &allow_dirs, false);
     if (regpat == NULL) {
       break;
     }
-    match = match_file_pat((char *)regpat, NULL, (char *)ffname, (char *)sfname, (char *)tail,
-                           (int)allow_dirs);
+    match = match_file_pat(regpat, NULL, ffname, sfname, tail, (int)allow_dirs);
     xfree(regpat);
     if (match) {
       return true;
diff --git a/src/nvim/fold.c b/src/nvim/fold.c
index 6cb9e5c38d..7306131574 100644
--- a/src/nvim/fold.c
+++ b/src/nvim/fold.c
@@ -2873,7 +2873,7 @@ static void foldlevelIndent(fline_T *flp)
 
   // empty line or lines starting with a character in 'foldignore': level
   // depends on surrounding lines
-  if (*s == NUL || vim_strchr(flp->wp->w_p_fdi, *s) != NULL) {
+  if (*s == NUL || vim_strchr(flp->wp->w_p_fdi, (uint8_t)(*s)) != NULL) {
     // first and last line can't be undefined, use level 0
     if (lnum == 1 || lnum == buf->b_ml.ml_line_count) {
       flp->lvl = 0;
diff --git a/src/nvim/garray.c b/src/nvim/garray.c
index 0f11868031..f75210bacb 100644
--- a/src/nvim/garray.c
+++ b/src/nvim/garray.c
@@ -173,9 +173,9 @@ char *ga_concat_strings_sep(const garray_T *gap, const char *sep)
 /// @param gap
 ///
 /// @returns the concatenated strings
-char_u *ga_concat_strings(const garray_T *gap) FUNC_ATTR_NONNULL_RET
+char *ga_concat_strings(const garray_T *gap) FUNC_ATTR_NONNULL_RET
 {
-  return (char_u *)ga_concat_strings_sep(gap, ",");
+  return ga_concat_strings_sep(gap, ",");
 }
 
 /// Concatenate a string to a growarray which contains characters.
diff --git a/src/nvim/getchar.c b/src/nvim/getchar.c
index b9e3b6b902..842b0b10b6 100644
--- a/src/nvim/getchar.c
+++ b/src/nvim/getchar.c
@@ -538,7 +538,7 @@ void AppendToRedobuffLit(const char *str, int len)
 
     // Handle a special or multibyte character.
     // Composing chars separately are handled separately.
-    const int c = mb_cptr2char_adv((const char_u **)&s);
+    const int c = mb_cptr2char_adv(&s);
     if (c < ' ' || c == DEL || (*s == NUL && (c == '0' || c == '^'))) {
       add_char_buff(&redobuff, Ctrl_V);
     }
@@ -599,7 +599,7 @@ void stuffReadbuffSpec(const char *s)
       stuffReadbuffLen(s, 3);
       s += 3;
     } else {
-      int c = mb_cptr2char_adv((const char_u **)&s);
+      int c = mb_cptr2char_adv(&s);
       if (c == CAR || c == NL || c == ESC) {
         c = ' ';
       }
@@ -640,7 +640,7 @@ void stuffescaped(const char *arg, bool literally)
 
     // stuff a single special character
     if (*arg != NUL) {
-      const int c = mb_cptr2char_adv((const char_u **)&arg);
+      const int c = mb_cptr2char_adv(&arg);
       if (literally && ((c < ' ' && c != TAB) || c == DEL)) {
         stuffcharReadbuff(Ctrl_V);
       }
diff --git a/src/nvim/help.c b/src/nvim/help.c
index 0a695a0aa7..91fda60859 100644
--- a/src/nvim/help.c
+++ b/src/nvim/help.c
@@ -412,7 +412,7 @@ int find_help_tags(const char *arg, int *num_matches, char ***matches, bool keep
     // And also "\_$" and "\_^".
     if (arg[0] == '\\'
         && ((arg[1] != NUL && arg[2] == NUL)
-            || (vim_strchr("%_z@", arg[1]) != NULL
+            || (vim_strchr("%_z@", (uint8_t)arg[1]) != NULL
                 && arg[2] != NUL))) {
       vim_snprintf(d, IOSIZE, "/\\\\%s", arg + 1);
       // Check for "/\\_$", should be "/\\_\$"
@@ -471,7 +471,7 @@ int find_help_tags(const char *arg, int *num_matches, char ***matches, bool keep
         // Insert '-' before and after "CTRL-X" when applicable.
         if (*s < ' '
             || (*s == '^' && s[1]
-                && (ASCII_ISALPHA(s[1]) || vim_strchr("?@[\\]^", s[1]) != NULL))) {
+                && (ASCII_ISALPHA(s[1]) || vim_strchr("?@[\\]^", (uint8_t)s[1]) != NULL))) {
           if (d > IObuff && d[-1] != '_' && d[-1] != '\\') {
             *d++ = '_';                 // prepend a '_' to make x_CTRL-x
           }
@@ -974,12 +974,12 @@ static void helptags_one(char *dir, const char *ext, const char *tagfname, bool
       }
       if (in_example) {
         // skip over example; a non-white in the first column ends it
-        if (vim_strchr(" \t\n\r", IObuff[0])) {
+        if (vim_strchr(" \t\n\r", (uint8_t)IObuff[0])) {
           continue;
         }
         in_example = false;
       }
-      p1 = vim_strchr((char *)IObuff, '*');       // find first '*'
+      p1 = vim_strchr(IObuff, '*');       // find first '*'
       while (p1 != NULL) {
         p2 = strchr((const char *)p1 + 1, '*');  // Find second '*'.
         if (p2 != NULL && p2 > p1 + 1) {         // Skip "*" and "**".
@@ -994,7 +994,7 @@ static void helptags_one(char *dir, const char *ext, const char *tagfname, bool
           // followed by a white character or end-of-line.
           if (s == p2
               && (p1 == IObuff || p1[-1] == ' ' || p1[-1] == '\t')
-              && (vim_strchr(" \t\n\r", s[1]) != NULL
+              && (vim_strchr(" \t\n\r", (uint8_t)s[1]) != NULL
                   || s[1] == '\0')) {
             *p2 = '\0';
             p1++;
diff --git a/src/nvim/highlight_group.c b/src/nvim/highlight_group.c
index 404835c4a9..2a81b4deb0 100644
--- a/src/nvim/highlight_group.c
+++ b/src/nvim/highlight_group.c
@@ -2921,9 +2921,9 @@ color_name_table_T color_name_table[] = {
 /// return the hex value or -1 if could not find a correct value
 RgbValue name_to_color(const char *name, int *idx)
 {
-  if (name[0] == '#' && isxdigit(name[1]) && isxdigit(name[2])
-      && isxdigit(name[3]) && isxdigit(name[4]) && isxdigit(name[5])
-      && isxdigit(name[6])