refactor: remove char_u (#22829)

Closes https://github.com/neovim/neovim/issues/459

40 files changed, 340 insertions, 1965 deletions

diff --git a/src/nvim/charset.c b/src/nvim/charset.c
index 63459495f8..2be8ccc456 100644
--- a/src/nvim/charset.c
+++ b/src/nvim/charset.c
@@ -55,7 +55,7 @@ static bool chartab_initialized = false;
   ((chartab)[(unsigned)(c) >> 6] & (1ull << ((c) & 0x3f)))
 
 // Table used below, see init_chartab() for an explanation
-static char_u g_chartab[256];
+static uint8_t g_chartab[256];
 
 // Flags for g_chartab[].
 #define CT_CELL_MASK  0x07  ///< mask: nr of display cells (1, 2 or 4)
@@ -286,7 +286,7 @@ void trans_characters(char *buf, int bufsize)
     if ((trs_len = utfc_ptr2len(buf)) > 1) {
       len -= trs_len;
     } else {
-      trs = (char *)transchar_byte((uint8_t)(*buf));
+      trs = transchar_byte((uint8_t)(*buf));
       trs_len = (int)strlen(trs);
 
       if (trs_len > 1) {
@@ -532,7 +532,7 @@ char *str_foldcase(char *str, int orglen, char *buf, int buflen)
 // Does NOT work for multi-byte characters, c must be <= 255.
 // Also doesn't work for the first byte of a multi-byte, "c" must be a
 // character!
-static char_u transchar_charbuf[11];
+static uint8_t transchar_charbuf[11];
 
 /// Translate a character into a printable one, leaving printable ASCII intact
 ///
@@ -543,10 +543,10 @@ static char_u transchar_charbuf[11];
 /// @return translated character into a static buffer.
 char *transchar(int c)
 {
-  return (char *)transchar_buf(curbuf, c);
+  return transchar_buf(curbuf, c);
 }
 
-char_u *transchar_buf(const buf_T *buf, int c)
+char *transchar_buf(const buf_T *buf, int c)
 {
   int i = 0;
   if (IS_SPECIAL(c)) {
@@ -560,14 +560,14 @@ char_u *transchar_buf(const buf_T *buf, int c)
   if ((!chartab_initialized && (c >= ' ' && c <= '~'))
       || ((c <= 0xFF) && vim_isprintc_strict(c))) {
     // printable character
-    transchar_charbuf[i] = (char_u)c;
+    transchar_charbuf[i] = (uint8_t)c;
     transchar_charbuf[i + 1] = NUL;
   } else if (c <= 0xFF) {
-    transchar_nonprint(buf, transchar_charbuf + i, c);
+    transchar_nonprint(buf, (char *)transchar_charbuf + i, c);
   } else {
     transchar_hex((char *)transchar_charbuf + i, c);
   }
-  return transchar_charbuf;
+  return (char *)transchar_charbuf;
 }
 
 /// Like transchar(), but called with a byte instead of a character.
@@ -577,7 +577,7 @@ char_u *transchar_buf(const buf_T *buf, int c)
 /// @param[in]  c  Byte to translate.
 ///
 /// @return pointer to translated character in transchar_charbuf.
-char_u *transchar_byte(const int c)
+char *transchar_byte(const int c)
   FUNC_ATTR_WARN_UNUSED_RESULT
 {
   return transchar_byte_buf(curbuf, c);
@@ -590,12 +590,12 @@ char_u *transchar_byte(const int c)
 /// @param[in]  c  Byte to translate.
 ///
 /// @return pointer to translated character in transchar_charbuf.
-char_u *transchar_byte_buf(const buf_T *buf, const int c)
+char *transchar_byte_buf(const buf_T *buf, const int c)
   FUNC_ATTR_WARN_UNUSED_RESULT
 {
   if (c >= 0x80) {
-    transchar_nonprint(buf, transchar_charbuf, c);
-    return transchar_charbuf;
+    transchar_nonprint(buf, (char *)transchar_charbuf, c);
+    return (char *)transchar_charbuf;
   }
   return transchar_buf(buf, c);
 }
@@ -609,7 +609,7 @@ char_u *transchar_byte_buf(const buf_T *buf, const int c)
 ///                       at least 5 bytes (conversion result + NUL).
 /// @param[in]  c  Character to convert. NUL is assumed to be NL according to
 ///                `:h NL-used-for-NUL`.
-void transchar_nonprint(const buf_T *buf, char_u *charbuf, int c)
+void transchar_nonprint(const buf_T *buf, char *charbuf, int c)
 {
   if (c == NL) {
     // we use newline in place of a NUL
@@ -622,12 +622,12 @@ void transchar_nonprint(const buf_T *buf, char_u *charbuf, int c)
 
   if (dy_flags & DY_UHEX || c > 0x7f) {
     // 'display' has "uhex"
-    transchar_hex((char *)charbuf, c);
+    transchar_hex(charbuf, c);
   } else {
     // 0x00 - 0x1f and 0x7f
     charbuf[0] = '^';
     // DEL displayed as ^?
-    charbuf[1] = (char_u)(c ^ 0x40);
+    charbuf[1] = (char)(uint8_t)(c ^ 0x40);
 
     charbuf[2] = NUL;
   }
diff --git a/src/nvim/charset.h b/src/nvim/charset.h
index e1ef06ef1d..f98ed94b87 100644
--- a/src/nvim/charset.h
+++ b/src/nvim/charset.h
@@ -54,6 +54,6 @@ static inline bool vim_isbreak(int c)
 /// Used very often if 'linebreak' is set
 static inline bool vim_isbreak(int c)
 {
-  return breakat_flags[(char_u)c];
+  return breakat_flags[(uint8_t)c];
 }
 #endif  // NVIM_CHARSET_H
diff --git a/src/nvim/drawline.c b/src/nvim/drawline.c
index 6d8cf1c7e1..caad88c212 100644
--- a/src/nvim/drawline.c
+++ b/src/nvim/drawline.c
@@ -2371,7 +2371,7 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool nochange,
           mb_c = c;
           mb_utf8 = check_mb_utf8(&c, u8cc);
         } else if (c != NUL) {
-          wlv.p_extra = (char *)transchar_buf(wp->w_buffer, c);
+          wlv.p_extra = transchar_buf(wp->w_buffer, c);
           if (wlv.n_extra == 0) {
             wlv.n_extra = byte2cells(c) - 1;
           }
diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index 26101d06ed..c551ec2726 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -1955,7 +1955,7 @@ static void insert_special(int c, int allow_modmask, int ctrlv)
     allow_modmask = true;
   }
   if (IS_SPECIAL(c) || (mod_mask && allow_modmask)) {
-    char *p = (char *)get_special_key_name(c, mod_mask);
+    char *p = get_special_key_name(c, mod_mask);
     int len = (int)strlen(p);
     c = (uint8_t)p[len - 1];
     if (len > 2) {
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index 25d383d8ea..4286e16eb1 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -6197,7 +6197,7 @@ static void f_resolve(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
   }
 # else
   char *v = os_realpath(fname, NULL);
-  rettv->vval.v_string = (char_u *)(v == NULL ? xstrdup(fname) : v);
+  rettv->vval.v_string = v == NULL ? xstrdup(fname) : v;
 # endif
 #endif
 
diff --git a/src/nvim/eval/typval_defs.h b/src/nvim/eval/typval_defs.h
index 4615198441..80432271b0 100644
--- a/src/nvim/eval/typval_defs.h
+++ b/src/nvim/eval/typval_defs.h
@@ -206,7 +206,7 @@ typedef struct {
   struct { \
     typval_T di_tv;  /* Structure that holds scope dictionary itself. */ \
     uint8_t di_flags;  /* Flags. */ \
-    char_u di_key[__VA_ARGS__];  /* Key value. */  /* NOLINT(runtime/arrays)*/ \
+    char di_key[__VA_ARGS__];  /* Key value. */  /* NOLINT(runtime/arrays)*/ \
   }
 
 /// Structure to hold a scope dictionary
diff --git a/src/nvim/eval/userfunc.c b/src/nvim/eval/userfunc.c
index 13779f4173..40bca9acc1 100644
--- a/src/nvim/eval/userfunc.c
+++ b/src/nvim/eval/userfunc.c
@@ -90,7 +90,7 @@ static int get_function_args(char **argp, char endchar, garray_T *newargs, int *
   bool mustend = false;
   char *arg = *argp;
   char *p = arg;
-  char_u c;
+  uint8_t c;
   int i;
 
   if (newargs != NULL) {
@@ -128,7 +128,7 @@ static int get_function_args(char **argp, char endchar, garray_T *newargs, int *
       }
       if (newargs != NULL) {
         ga_grow(newargs, 1);
-        c = (char_u)(*p);
+        c = (uint8_t)(*p);
         *p = NUL;
         arg = xstrdup(arg);
 
@@ -159,7 +159,7 @@ static int get_function_args(char **argp, char endchar, garray_T *newargs, int *
           while (p > expr && ascii_iswhite(p[-1])) {
             p--;
           }
-          c = (char_u)(*p);
+          c = (uint8_t)(*p);
           *p = NUL;
           expr = xstrdup(expr);
           ((char **)(default_args->ga_data))[default_args->ga_len] = expr;
diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index 621cb764f4..705f0fe83d 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -149,7 +149,7 @@ void do_ascii(const exarg_T *const eap)
     char buf1[20];
     if (vim_isprintc_strict(c) && (c < ' ' || c > '~')) {
       char buf3[7];
-      transchar_nonprint(curbuf, (char_u *)buf3, c);
+      transchar_nonprint(curbuf, buf3, c);
       vim_snprintf(buf1, sizeof(buf1), "  <%s>", (char *)buf3);
     } else {
       buf1[0] = NUL;
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index 5112505eda..bd7ddbf567 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -2117,7 +2117,7 @@ static int command_line_handle_key(CommandLineState *s)
 
   // put the character in the command line
   if (IS_SPECIAL(s->c) || mod_mask != 0) {
-    put_on_cmdline((char *)get_special_key_name(s->c, mod_mask), -1, true);
+    put_on_cmdline(get_special_key_name(s->c, mod_mask), -1, true);
   } else {
     int j = utf_char2bytes(s->c, IObuff);
     IObuff[j] = NUL;                // exclude composing chars
diff --git a/src/nvim/file_search.c b/src/nvim/file_search.c
index e27c7c4349..d91e2dfeeb 100644
--- a/src/nvim/file_search.c
+++ b/src/nvim/file_search.c
@@ -794,7 +794,7 @@ char *vim_findfile(void *search_ctx_arg)
                   ) {
 #ifdef FF_VERBOSE
                 if (ff_check_visited(&search_ctx->ffsc_visited_list->ffvl_visited_list,
-                                     file_path, (char_u *)"") == FAIL) {
+                                     file_path, "") == FAIL) {
                   if (p_verbose >= 5) {
                     verbose_enter_scroll();
                     smsg("Already: %s", file_path);
diff --git a/src/nvim/generators/gen_ex_cmds.lua b/src/nvim/generators/gen_ex_cmds.lua
index 935d7b333e..26edd33604 100644
--- a/src/nvim/generators/gen_ex_cmds.lua
+++ b/src/nvim/generators/gen_ex_cmds.lua
@@ -41,7 +41,7 @@ static const uint16_t cmdidxs1[%u] = {
 -- Values in cmdidxs2[c1][c2] are relative to cmdidxs1[c1] so that they
 -- fit in a byte.
 local cmdidxs2_out = string.format([[
-static const char_u cmdidxs2[%u][%u] = {
+static const uint8_t cmdidxs2[%u][%u] = {
   /*           a   b   c   d   e   f   g   h   i   j   k   l   m   n   o   p   q   r   s   t   u   v   w   x   y   z */
 ]], a_to_z, a_to_z)
 
diff --git a/src/nvim/generators/gen_options.lua b/src/nvim/generators/gen_options.lua
index edb7dae159..54b97c5286 100644
--- a/src/nvim/generators/gen_options.lua
+++ b/src/nvim/generators/gen_options.lua
@@ -139,7 +139,7 @@ local dump_option = function(i, o)
     w(get_cond(o.enable_if))
   end
   if o.varname then
-    w('    .var=(char_u *)&' .. o.varname)
+    w('    .var=(char *)&' .. o.varname)
   elseif #o.scope == 1 and o.scope[1] == 'window' then
     w('    .var=VAR_WIN')
   end
diff --git a/src/nvim/keycodes.c b/src/nvim/keycodes.c
index f3d379c2e9..8eec9014f7 100644
--- a/src/nvim/keycodes.c
+++ b/src/nvim/keycodes.c
@@ -34,18 +34,18 @@
 static const struct modmasktable {
   uint16_t mod_mask;  ///< Bit-mask for particular key modifier.
   uint16_t mod_flag;  ///< Bit(s) for particular key modifier.
-  char_u name;  ///< Single letter name of modifier.
+  char name;  ///< Single letter name of modifier.
 } mod_mask_table[] = {
-  { MOD_MASK_ALT,              MOD_MASK_ALT,           (char_u)'M' },
-  { MOD_MASK_META,             MOD_MASK_META,          (char_u)'T' },
-  { MOD_MASK_CTRL,             MOD_MASK_CTRL,          (char_u)'C' },
-  { MOD_MASK_SHIFT,            MOD_MASK_SHIFT,         (char_u)'S' },
-  { MOD_MASK_MULTI_CLICK,      MOD_MASK_2CLICK,        (char_u)'2' },
-  { MOD_MASK_MULTI_CLICK,      MOD_MASK_3CLICK,        (char_u)'3' },
-  { MOD_MASK_MULTI_CLICK,      MOD_MASK_4CLICK,        (char_u)'4' },
-  { MOD_MASK_CMD,              MOD_MASK_CMD,           (char_u)'D' },
+  { MOD_MASK_ALT,              MOD_MASK_ALT,           'M' },
+  { MOD_MASK_META,             MOD_MASK_META,          'T' },
+  { MOD_MASK_CTRL,             MOD_MASK_CTRL,          'C' },
+  { MOD_MASK_SHIFT,            MOD_MASK_SHIFT,         'S' },
+  { MOD_MASK_MULTI_CLICK,      MOD_MASK_2CLICK,        '2' },
+  { MOD_MASK_MULTI_CLICK,      MOD_MASK_3CLICK,        '3' },
+  { MOD_MASK_MULTI_CLICK,      MOD_MASK_4CLICK,        '4' },
+  { MOD_MASK_CMD,              MOD_MASK_CMD,           'D' },
   // 'A' must be the last one
-  { MOD_MASK_ALT,              MOD_MASK_ALT,           (char_u)'A' },
+  { MOD_MASK_ALT,              MOD_MASK_ALT,           'A' },
   { 0, 0, NUL }
   // NOTE: when adding an entry, update MAX_KEY_NAME_LEN!
 };
@@ -386,7 +386,7 @@ int name_to_mod_mask(int c)
 {
   c = TOUPPER_ASC(c);
   for (size_t i = 0; mod_mask_table[i].mod_mask != 0; i++) {
-    if (c == mod_mask_table[i].name) {
+    if (c == (uint8_t)mod_mask_table[i].name) {
       return mod_mask_table[i].mod_flag;
     }
   }
@@ -468,9 +468,9 @@ int handle_x_keys(const int key)
 }
 
 /// @return  a string which contains the name of the given key when the given modifiers are down.
-char_u *get_special_key_name(int c, int modifiers)
+char *get_special_key_name(int c, int modifiers)
 {
-  static char_u string[MAX_KEY_NAME_LEN + 1];
+  static char string[MAX_KEY_NAME_LEN + 1];
 
   int i, idx;
   int table_idx;
@@ -524,7 +524,7 @@ char_u *get_special_key_name(int c, int modifiers)
     if ((modifiers & mod_mask_table[i].mod_mask)
         == mod_mask_table[i].mod_flag) {
       string[idx++] = mod_mask_table[i].name;
-      string[idx++] = (char_u)'-';
+      string[idx++] = '-';
     }
   }
 
@@ -532,18 +532,18 @@ char_u *get_special_key_name(int c, int modifiers)
     if (IS_SPECIAL(c)) {
       string[idx++] = 't';
       string[idx++] = '_';
-      string[idx++] = (char_u)KEY2TERMCAP0(c);
-      string[idx++] = KEY2TERMCAP1(c);
+      string[idx++] = (char)(uint8_t)KEY2TERMCAP0(c);
+      string[idx++] = (char)(uint8_t)KEY2TERMCAP1(c);
     } else {
       // Not a special key, only modifiers, output directly.
       if (utf_char2len(c) > 1) {
-        idx += utf_char2bytes(c, (char *)string + idx);
+        idx += utf_char2bytes(c, string + idx);
       } else if (vim_isprintc(c)) {
-        string[idx++] = (char_u)c;
+        string[idx++] = (char)(uint8_t)c;
       } else {
         s = transchar(c);
         while (*s) {
-          string[idx++] = (uint8_t)(*s++);
+          string[idx++] = *s++;
         }
       }
     }
@@ -1083,7 +1083,7 @@ char *vim_strsave_escape_ks(char *p)
 /// vim_strsave_escape_ks().  Works in-place.
 void vim_unescape_ks(char *p)
 {
-  char_u *s = (char_u *)p, *d = (char_u *)p;
+  uint8_t *s = (uint8_t *)p, *d = (uint8_t *)p;
 
   while (*s != NUL) {
     if (s[0] == K_SPECIAL && s[1] == KS_SPECIAL && s[2] == KE_FILLER) {
diff --git a/src/nvim/mapping.c b/src/nvim/mapping.c
index 5cedc5e97d..2941d5965b 100644
--- a/src/nvim/mapping.c
+++ b/src/nvim/mapping.c
@@ -1189,7 +1189,7 @@ static char *translate_mapping(char *str_in, int cpo_flags)
         str += 2;
       }
       if (IS_SPECIAL(c) || modifiers) {         // special key
-        ga_concat(&ga, (char *)get_special_key_name(c, modifiers));
+        ga_concat(&ga, get_special_key_name(c, modifiers));
         continue;         // for (str)
       }
     }
@@ -1436,7 +1436,7 @@ int ExpandMappings(char *pat, regmatch_T *regmatch, int *numMatches, char ***mat
 bool check_abbr(int c, char *ptr, int col, int mincol)
 {
   int scol;                     // starting column of the abbr.
-  char_u tb[MB_MAXBYTES + 4];
+  uint8_t tb[MB_MAXBYTES + 4];
   mapblock_T *mp;
   mapblock_T *mp2;
   int clen = 0;                 // length in characters
@@ -1535,8 +1535,8 @@ bool check_abbr(int c, char *ptr, int col, int mincol)
         // special key code, split up
         if (IS_SPECIAL(c) || c == K_SPECIAL) {
           tb[j++] = K_SPECIAL;
-          tb[j++] = (char_u)K_SECOND(c);
-          tb[j++] = (char_u)K_THIRD(c);
+          tb[j++] = (uint8_t)K_SECOND(c);
+          tb[j++] = (uint8_t)K_THIRD(c);
         } else {
           if (c < ABBR_OFF && (c < ' ' || c > '~')) {
             tb[j++] = Ctrl_V;                   // special char needs CTRL-V
@@ -1918,7 +1918,7 @@ int put_escstr(FILE *fd, char *strstart, int what)
         str += 2;
       }
       if (IS_SPECIAL(c) || modifiers) {         // special key
-        if (fputs((char *)get_special_key_name(c, modifiers), fd) < 0) {
+        if (fputs(get_special_key_name(c, modifiers), fd) < 0) {
           return FAIL;
         }
         continue;
diff --git a/src/nvim/mbyte.c b/src/nvim/mbyte.c
index fb52a11025..c580dc29e6 100644
--- a/src/nvim/mbyte.c
+++ b/src/nvim/mbyte.c
@@ -653,32 +653,32 @@ int utf_ptr2char(const char *const p_in)
 //
 // If byte sequence is illegal or incomplete, returns -1 and does not advance
 // "s".
-static int utf_safe_read_char_adv(const char_u **s, size_t *n)
+static int utf_safe_read_char_adv(const char **s, size_t *n)
 {
   if (*n == 0) {  // end of buffer
     return 0;
   }
 
-  uint8_t k = utf8len_tab_zero[**s];
+  uint8_t k = utf8len_tab_zero[(uint8_t)(**s)];
 
   if (k == 1) {
     // ASCII character or NUL
     (*n)--;
-    return *(*s)++;
+    return (uint8_t)(*(*s)++);
   }
 
   if (k <= *n) {
     // We have a multibyte sequence and it isn't truncated by buffer
     // limits so utf_ptr2char() is safe to use. Or the first byte is
     // illegal (k=0), and it's also safe to use utf_ptr2char().
-    int c = utf_ptr2char((char *)(*s));
+    int c = utf_ptr2char(*s);
 
     // On failure, utf_ptr2char() returns the first byte, so here we
     // check equality with the first byte. The only non-ASCII character
     // which equals the first byte of its own UTF-8 representation is
     // U+00C3 (UTF-8: 0xC3 0x83), so need to check that special case too.
     // It's safe even if n=1, else we would have k=2 > n.
-    if (c != (int)(**s) || (c == 0xC3 && (*s)[1] == 0x83)) {
+    if (c != (int)((uint8_t)(**s)) || (c == 0xC3 && (uint8_t)(*s)[1] == 0x83)) {
       // byte sequence was successfully decoded
       *s += k;
       *n -= k;
@@ -1271,7 +1271,7 @@ bool mb_isalpha(int a)
   return mb_islower(a) || mb_isupper(a);
 }
 
-static int utf_strnicmp(const char_u *s1, const char_u *s2, size_t n1, size_t n2)
+static int utf_strnicmp(const char *s1, const char *s2, size_t n1, size_t n2)
 {
   int c1, c2, cdiff;
   char buffer[6];
@@ -1313,14 +1313,14 @@ static int utf_strnicmp(const char_u *s1, const char_u *s2, size_t n1, size_t n2
 
   if (c1 != -1 && c2 == -1) {
     n1 = (size_t)utf_char2bytes(utf_fold(c1), (char *)buffer);
-    s1 = (char_u *)buffer;
+    s1 = buffer;
   } else if (c2 != -1 && c1 == -1) {
     n2 = (size_t)utf_char2bytes(utf_fold(c2), (char *)buffer);
-    s2 = (char_u *)buffer;
+    s2 = buffer;
   }
 
   while (n1 > 0 && n2 > 0 && *s1 != NUL && *s2 != NUL) {
-    cdiff = (int)(*s1) - (int)(*s2);
+    cdiff = (int)((uint8_t)(*s1)) - (int)((uint8_t)(*s2));
     if (cdiff != 0) {
       return cdiff;
     }
@@ -1498,7 +1498,7 @@ ssize_t mb_utf_index_to_bytes(const char *s, size_t len, size_t index, bool use_
 ///          two characters otherwise.
 int mb_strnicmp(const char *s1, const char *s2, const size_t nn)
 {
-  return utf_strnicmp((char_u *)s1, (char_u *)s2, nn, nn);
+  return utf_strnicmp(s1, s2, nn, nn);
 }
 
 /// Compare strings case-insensitively
diff --git a/src/nvim/memline.c b/src/nvim/memline.c
index 0f2790b06c..51a4186775 100644
--- a/src/nvim/memline.c
+++ b/src/nvim/memline.c
@@ -351,7 +351,7 @@ int ml_open(buf_T *buf)
   dp->db_index[0] = --dp->db_txt_start;         // at end of block
   dp->db_free -= 1 + (unsigned)INDEX_SIZE;
   dp->db_line_count = 1;
-  *((char_u *)dp + dp->db_txt_start) = NUL;     // empty line
+  *((char *)dp + dp->db_txt_start) = NUL;     // empty line
 
   return OK;
 
@@ -1065,7 +1065,7 @@ void ml_recover(bool checkext)
           }
 
           // make sure there is a NUL at the end of the block
-          *((char_u *)dp + dp->db_txt_end - 1) = NUL;
+          *((char *)dp + dp->db_txt_end - 1) = NUL;
 
           // check number of lines in block
           // if wrong, use count in data block
diff --git a/src/nvim/message.c b/src/nvim/message.c
index 98ef6e5cba..b43bc6ce9b 100644
--- a/src/nvim/message.c
+++ b/src/nvim/message.c
@@ -1589,7 +1589,7 @@ int msg_outtrans_len_attr(const char *msgstr, int len, int attr)
       len -= mb_l - 1;
       str += mb_l;
     } else {
-      s = (char *)transchar_byte_buf(NULL, (uint8_t)(*str));
+      s = transchar_byte_buf(NULL, (uint8_t)(*str));
       if (s[1] != NUL) {
         // Unprintable char: print the printable chars so far and the
         // translation of the unprintable char.
@@ -1671,7 +1671,7 @@ int msg_outtrans_special(const char *strstart, bool from, int maxlen)
     }
     if (text[0] != NUL && text[1] == NUL) {
       // single-byte character or illegal byte
-      text = (char *)transchar_byte_buf(NULL, (uint8_t)text[0]);
+      text = transchar_byte_buf(NULL, (uint8_t)text[0]);
     }
     const int len = vim_strsize(text);
     if (maxlen > 0 && retval + len >= maxlen) {
@@ -1917,7 +1917,7 @@ void msg_prt_line(char *s, int list)
         s--;
       } else if (c != NUL && (n = byte2cells(c)) > 1) {
         n_extra = n - 1;
-        p_extra = (char *)transchar_byte_buf(NULL, c);
+        p_extra = transchar_byte_buf(NULL, c);
         c_extra = NUL;
         c_final = NUL;
         c = (unsigned char)(*p_extra++);
diff --git a/src/nvim/ops.c b/src/nvim/ops.c
index 2edd1772ca..d66ed9abff 100644
--- a/src/nvim/ops.c
+++ b/src/nvim/ops.c
@@ -5162,7 +5162,7 @@ void write_reg_contents_ex(int name, const char *str, ssize_t len, bool must_app
 /// @param str string or list of strings to put in register
 /// @param len length of the string (Ignored when str_list=true.)
 /// @param blocklen width of visual block, or -1 for "I don't know."
-/// @param str_list True if str is `char_u **`.
+/// @param str_list True if str is `char **`.
 static void str_to_reg(yankreg_T *y_ptr, MotionType yank_type, const char *str, size_t len,
                        colnr_T blocklen, bool str_list)
   FUNC_ATTR_NONNULL_ALL
diff --git a/src/nvim/option.c b/src/nvim/option.c
index f672b3ab6f..8fa719c3a9 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -421,7 +421,7 @@ static void set_option_default(const int opt_idx, int opt_flags)
 
   // pointer to variable for current option
   vimoption_T *opt = &options[opt_idx];
-  char_u *varp = (char_u *)get_varp_scope(opt, both ? OPT_LOCAL : opt_flags);
+  char *varp = get_varp_scope(opt, both ? OPT_LOCAL : opt_flags);
   uint32_t flags = opt->flags;
   if (varp != NULL) {       // skip hidden option, nothing to do for it
     if (flags & P_STRING) {
@@ -833,7 +833,7 @@ static void do_set_num(int opt_idx, int opt_flags, char **argp, int nextchar, co
   if (op == OP_REMOVING) {
     value = *(long *)varp - value;
   }
-  *errmsg = set_num_option(opt_idx, (char_u *)varp, (long)value,
+  *errmsg = set_num_option(opt_idx, (char *)varp, (long)value,
                            errbuf, errbuflen, opt_flags);
 }
 
@@ -847,7 +847,7 @@ static void munge_string_opt_val(char **varp, char **oldval, char **const origva
   if (varp == &p_kp && (**argp == NUL || **argp == ' ')) {
     *save_argp = *argp;
     *argp = ":help";
-  } else if (varp == &p_bs && ascii_isdigit(**(char_u **)varp)) {
+  } else if (varp == &p_bs && ascii_isdigit((uint8_t)(**varp))) {
     // Convert 'backspace' number to string, for
     // adding, prepending and removing string.
     const int i = getdigits_int(varp, true, 0);
@@ -927,7 +927,7 @@ static void do_set_string(int opt_idx, int opt_flags, char **argp, int nextchar,
   // reset, use the global value here.
   if ((opt_flags & (OPT_LOCAL | OPT_GLOBAL)) == 0
       && ((int)options[opt_idx].indir & PV_BOTH)) {
-    varp = (char *)options[opt_idx].var;
+    varp = options[opt_idx].var;
   }
 
   // The old value is kept until we are sure that the new value is valid.
@@ -1439,7 +1439,7 @@ static void do_set_option(int opt_flags, char **argp, bool *did_show, char *errb
       showoneopt(&options[opt_idx], opt_flags);
       if (p_verbose > 0) {
         // Mention where the option was last set.
-        if (varp == (char *)options[opt_idx].var) {
+        if (varp == options[opt_idx].var) {
           option_last_set_msg(options[opt_idx].last_set);
         } else if ((int)options[opt_idx].indir & PV_WIN) {
           option_last_set_msg(curwin->w_p_script_ctx[(int)options[opt_idx].indir & PV_MASK]);
@@ -1735,7 +1735,7 @@ static char *option_expand(int opt_idx, char *val)
   // For 'spellsuggest' expand after "file:".
   expand_env_esc(val, NameBuff, MAXPATHL,
                  (char **)options[opt_idx].var == &p_tags, false,
-                 (char_u **)options[opt_idx].var == (char_u **)&p_sps ? "file:" :
+                 (char **)options[opt_idx].var == &p_sps ? "file:" :
                  NULL);
   if (strcmp(NameBuff, val) == 0) {   // they are the same
     return NULL;
@@ -2274,7 +2274,7 @@ static char *set_bool_option(const int opt_idx, char *const varp, const int valu
 /// @param[in]  opt_flags  OPT_LOCAL, OPT_GLOBAL or OPT_MODELINE.
 ///
 /// @return NULL on success, error message on error.
-static char *set_num_option(int opt_idx, char_u *varp, long value, char *errbuf, size_t errbuflen,
+static char *set_num_option(int opt_idx, char *varp, long value, char *errbuf, size_t errbuflen,
                             int opt_flags)
 {
   char *errmsg = NULL;
@@ -2905,7 +2905,7 @@ getoption_T get_option_value(const char *name, long *numval, char **stringval, u
     return gov_unknown;
   }
 
-  char_u *varp = (char_u *)get_varp_scope(&(options[opt_idx]), scope);