refactor: replace char_u with char 25 (#21838)

refactor: replace char_u with char

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

44 files changed, 468 insertions, 476 deletions

diff --git a/cmake.config/pathdef.c.in b/cmake.config/pathdef.c.in
index 6a8a2b205a..5d6dfa6b9f 100644
--- a/cmake.config/pathdef.c.in
+++ b/cmake.config/pathdef.c.in
@@ -4,5 +4,5 @@
 char *default_vim_dir = "${CMAKE_INSTALL_FULL_DATAROOTDIR}/nvim";
 char *default_vimruntime_dir = "";
 char *default_lib_dir = "${CMAKE_INSTALL_FULL_LIBDIR}/nvim";
-char_u *compiled_user = (char_u *)"${USERNAME}";
-char_u *compiled_sys = (char_u *)"${HOSTNAME}";
+char *compiled_user = "${USERNAME}";
+char *compiled_sys = "${HOSTNAME}";
diff --git a/src/nvim/debugger.c b/src/nvim/debugger.c
index ad615969ba..f7e70a78ce 100644
--- a/src/nvim/debugger.c
+++ b/src/nvim/debugger.c
@@ -403,7 +403,7 @@ void ex_debug(exarg_T *eap)
   debug_break_level = debug_break_level_save;
 }
 
-static char_u *debug_breakpoint_name = NULL;
+static char *debug_breakpoint_name = NULL;
 static linenr_T debug_breakpoint_lnum;
 
 /// When debugging or a breakpoint is set on a skipped command, no debug prompt
@@ -412,7 +412,7 @@ static linenr_T debug_breakpoint_lnum;
 /// a skipped command decides itself that a debug prompt should be displayed, it
 /// can do so by calling dbg_check_skipped().
 static int debug_skipped;
-static char_u *debug_skipped_name;
+static char *debug_skipped_name;
 
 /// Go to debug mode when a breakpoint was encountered or "ex_nesting_level" is
 /// at or below the break level.  But only when the line is actually
@@ -426,8 +426,8 @@ void dbg_check_breakpoint(exarg_T *eap)
     if (!eap->skip) {
       char *p;
       // replace K_SNR with "<SNR>"
-      if (debug_breakpoint_name[0] == K_SPECIAL
-          && debug_breakpoint_name[1] == KS_EXTRA
+      if ((uint8_t)debug_breakpoint_name[0] == K_SPECIAL
+          && (uint8_t)debug_breakpoint_name[1] == KS_EXTRA
           && debug_breakpoint_name[2] == KE_SNR) {
         p = "<SNR>";
       } else {
@@ -857,6 +857,6 @@ static linenr_T debuggy_find(bool file, char *fname, linenr_T after, garray_T *g
 void dbg_breakpoint(char *name, linenr_T lnum)
 {
   // We need to check if this line is actually executed in do_one_cmd()
-  debug_breakpoint_name = (char_u *)name;
+  debug_breakpoint_name = name;
   debug_breakpoint_lnum = lnum;
 }
diff --git a/src/nvim/diff.c b/src/nvim/diff.c
index 7fbde4f45b..032de561b3 100644
--- a/src/nvim/diff.c
+++ b/src/nvim/diff.c
@@ -1218,7 +1218,7 @@ void ex_diffpatch(exarg_T *eap)
   fullname = FullName_save(eap->arg, false);
   esc_name = vim_strsave_shellescape(fullname != NULL ? fullname : eap->arg, true, true);
 #else
-  esc_name = (char *)vim_strsave_shellescape(eap->arg, true, true);
+  esc_name = vim_strsave_shellescape(eap->arg, true, true);
 #endif
   size_t buflen = strlen(tmp_orig) + strlen(esc_name) + strlen(tmp_new) + 16;
   buf = xmalloc(buflen);
diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index bf4563caa1..32c035b028 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -323,7 +323,7 @@ static void insert_enter(InsertState *s)
 
   // Get the current length of the redo buffer, those characters have to be
   // skipped if we want to get to the inserted characters.
-  s->ptr = (char *)get_inserted();
+  s->ptr = get_inserted();
   if (s->ptr == NULL) {
     new_insert_skip = 0;
   } else {
@@ -2303,7 +2303,7 @@ static void stop_insert(pos_T *end_insert_pos, int esc, int nomove)
   // Save the inserted text for later redo with ^@ and CTRL-A.
   // Don't do it when "restart_edit" was set and nothing was inserted,
   // otherwise CTRL-O w and then <Left> will clear "last_insert".
-  ptr = (char *)get_inserted();
+  ptr = get_inserted();
   if (did_restart_edit == 0 || (ptr != NULL
                                 && (int)strlen(ptr) > new_insert_skip)) {
     xfree(last_insert);
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index a9ea298285..45b492be80 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -5002,7 +5002,7 @@ void common_function(typval_T *argvars, typval_T *rettv, bool is_funcref)
     // Don't check an autoload name for existence here.
   } else if (trans_name != NULL
              && (is_funcref
-                 ? find_func((char_u *)trans_name) == NULL
+                 ? find_func(trans_name) == NULL
                  : !translated_function_exists((const char *)trans_name))) {
     semsg(_("E700: Unknown function: %s"), s);
   } else {
@@ -5101,7 +5101,7 @@ void common_function(typval_T *argvars, typval_T *rettv, bool is_funcref)
         func_ptr_ref(pt->pt_func);
         xfree(name);
       } else if (is_funcref) {
-        pt->pt_func = find_func((char_u *)trans_name);
+        pt->pt_func = find_func(trans_name);
         func_ptr_ref(pt->pt_func);
         xfree(name);
       } else {
@@ -5536,7 +5536,7 @@ bool callback_from_typval(Callback *const callback, const typval_T *const arg)
     }
   } else if (nlua_is_table_from_lua(arg)) {
     // TODO(tjdvries): UnifiedCallback
-    char *name = (char *)nlua_register_table_as_callable(arg);
+    char *name = nlua_register_table_as_callable(arg);
 
     if (name != NULL) {
       callback->data.funcref = xstrdup(name);
@@ -8299,7 +8299,7 @@ bool eval_has_provider(const char *feat)
     if (get_var_tv(buf, len, &tv, NULL, false, true) == FAIL) {
       // Show a hint if Call() is defined but g:loaded_xx_provider is missing.
       snprintf(buf, sizeof(buf), "provider#%s#Call", name);
-      if (!!find_func((char_u *)buf) && p_lpl) {
+      if (!!find_func(buf) && p_lpl) {
         semsg("provider: %s: missing required variable g:loaded_%s_provider",
               name, name);
       }
@@ -8314,7 +8314,7 @@ bool eval_has_provider(const char *feat)
   if (ok) {
     // Call() must be defined if provider claims to be working.
     snprintf(buf, sizeof(buf), "provider#%s#Call", name);
-    if (!find_func((char_u *)buf)) {
+    if (!find_func(buf)) {
       semsg("provider: %s: g:loaded_%s_provider=2 but %s is not defined",
             name, name, buf);
       ok = false;
@@ -8337,10 +8337,10 @@ void eval_fmt_source_name_line(char *buf, size_t bufsize)
 /// ":checkhealth [plugins]"
 void ex_checkhealth(exarg_T *eap)
 {
-  bool found = !!find_func((char_u *)"health#check");
+  bool found = !!find_func("health#check");
   if (!found
       && script_autoload("health#check", sizeof("health#check") - 1, false)) {
-    found = !!find_func((char_u *)"health#check");
+    found = !!find_func("health#check");
   }
   if (!found) {
     const char *vimruntime_env = os_getenv("VIMRUNTIME");
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index 91ab9f14ff..1b34777a46 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -557,7 +557,7 @@ static void f_call(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
     func = partial_name(partial);
   } else if (nlua_is_table_from_lua(&argvars[0])) {
     // TODO(tjdevries): UnifiedCallback
-    func = (char *)nlua_register_table_as_callable(&argvars[0]);
+    func = nlua_register_table_as_callable(&argvars[0]);
     owned = true;
   } else {
     func = (char *)tv_get_string(&argvars[0]);
@@ -1419,7 +1419,7 @@ static void f_diff_hlID(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
       hlID = HLF_CHD;  // Changed line.
     }
   }
-  rettv->vval.v_number = hlID == (hlf_T)0 ? 0 : (int)(hlID + 1);
+  rettv->vval.v_number = hlID == (hlf_T)0 ? 0 : (hlID + 1);
 }
 
 /// "empty({expr})" function
@@ -1695,7 +1695,7 @@ static void f_exepath(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
 
 #ifdef BACKSLASH_IN_FILENAME
   if (path != NULL) {
-    slash_adjust((char_u *)path);
+    slash_adjust(path);
   }
 #endif
 
@@ -1749,7 +1749,7 @@ static void f_expand(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
   int options = WILD_SILENT|WILD_USE_NL|WILD_LIST_NOTFOUND;
   bool error = false;
 #ifdef BACKSLASH_IN_FILENAME
-  char_u *p_csl_save = p_csl;
+  char *p_csl_save = p_csl;
 
   // avoid using 'completeslash' here
   p_csl = empty_option;
@@ -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 *)s, (char_u *)s, &len, NULL, &errormsg, NULL, false);
+    char *result = eval_vars((char *)s, s, &len, NULL, &errormsg, NULL, false);
     if (p_verbose == 0) {
       emsg_off--;
     } else if (errormsg != NULL) {
@@ -2022,7 +2022,7 @@ static void f_filewritable(typval_T *argvars, typval_T *rettv, EvalFuncData fptr
 static void findfilendir(typval_T *argvars, typval_T *rettv, int find_what)
 {
   char *fresult = NULL;
-  char *path = *curbuf->b_p_path == NUL ? (char *)p_path : curbuf->b_p_path;
+  char *path = *curbuf->b_p_path == NUL ? p_path : curbuf->b_p_path;
   int count = 1;
   bool first = true;
   bool error = false;
@@ -7827,7 +7827,7 @@ static void f_strftime(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
     vimconv_T conv;
 
     conv.vc_type = CONV_NONE;
-    char *enc = (char *)enc_locale();
+    char *enc = enc_locale();
     convert_setup(&conv, p_enc, enc);
     if (conv.vc_type != CONV_NONE) {
       p = string_convert(&conv, p, NULL);
@@ -8097,7 +8097,7 @@ static void f_strptime(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
   vimconv_T conv = {
     .vc_type = CONV_NONE,
   };
-  char *enc = (char *)enc_locale();
+  char *enc = enc_locale();
   convert_setup(&conv, p_enc, enc);
   if (conv.vc_type != CONV_NONE) {
     fmt = string_convert(&conv, fmt, NULL);
diff --git a/src/nvim/eval/typval.c b/src/nvim/eval/typval.c
index b48aa1372e..9ffc4d4696 100644
--- a/src/nvim/eval/typval.c
+++ b/src/nvim/eval/typval.c
@@ -3007,7 +3007,7 @@ void tv_blob_copy(typval_T *const from, typval_T *const to)
     (tv)->v_lock = VAR_UNLOCKED; \
   } while (0)
 
-static inline int _nothing_conv_func_start(typval_T *const tv, char_u *const fun)
+static inline int _nothing_conv_func_start(typval_T *const tv, char *const fun)
   FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_ALWAYS_INLINE FUNC_ATTR_NONNULL_ARG(1)
 {
   tv->v_lock = VAR_UNLOCKED;
@@ -3019,7 +3019,7 @@ static inline int _nothing_conv_func_start(typval_T *const tv, char_u *const fun
       return OK;
     }
   } else {
-    func_unref((char *)fun);
+    func_unref(fun);
     if ((const char *)fun != tv_empty_string) {
       xfree(fun);
     }
diff --git a/src/nvim/eval/typval_encode.c.h b/src/nvim/eval/typval_encode.c.h
index 6c931d3f88..6d29286a58 100644
--- a/src/nvim/eval/typval_encode.c.h
+++ b/src/nvim/eval/typval_encode.c.h
@@ -339,7 +339,7 @@ static int _TYPVAL_ENCODE_CONVERT_ONE_VALUE(
                             tv_blob_len(tv->vval.v_blob));
     break;
   case VAR_FUNC:
-    TYPVAL_ENCODE_CONV_FUNC_START(tv, (char_u *)tv->vval.v_string);
+    TYPVAL_ENCODE_CONV_FUNC_START(tv, tv->vval.v_string);
     TYPVAL_ENCODE_CONV_FUNC_BEFORE_ARGS(tv, 0);
     TYPVAL_ENCODE_CONV_FUNC_BEFORE_SELF(tv, -1);
     TYPVAL_ENCODE_CONV_FUNC_END(tv);
@@ -347,7 +347,7 @@ static int _TYPVAL_ENCODE_CONVERT_ONE_VALUE(
   case VAR_PARTIAL: {
     partial_T *const pt = tv->vval.v_partial;
     (void)pt;
-    TYPVAL_ENCODE_CONV_FUNC_START(tv, (pt == NULL ? NULL : (char_u *)partial_name(pt)));  // -V547
+    TYPVAL_ENCODE_CONV_FUNC_START(tv, (pt == NULL ? NULL : partial_name(pt)));  // -V547
     _mp_push(*mpstack, ((MPConvStackVal) {  // -V779
         .type = kMPConvPartial,
         .tv = tv,
diff --git a/src/nvim/eval/userfunc.c b/src/nvim/eval/userfunc.c
index 74d9e30a58..22c5b1954d 100644
--- a/src/nvim/eval/userfunc.c
+++ b/src/nvim/eval/userfunc.c
@@ -582,9 +582,9 @@ static char *fname_trans_sid(const char *const name, char *const fname_buf, char
 /// Find a function by name, return pointer to it in ufuncs.
 ///
 /// @return  NULL for unknown function.
-ufunc_T *find_func(const char_u *name)
+ufunc_T *find_func(const char *name)
 {
-  hashitem_T *hi = hash_find(&func_hashtab, (char *)name);
+  hashitem_T *hi = hash_find(&func_hashtab, name);
   if (!HASHITEM_EMPTY(hi)) {
     return HI2UF(hi);
   }
@@ -1580,7 +1580,7 @@ int call_func(const char *funcname, int len, typval_T *rettv, int argcount_in, t
     } else if (fp != NULL || !builtin_function((const char *)rfname, -1)) {
       // User defined function.
       if (fp == NULL) {
-        fp = find_func((char_u *)rfname);
+        fp = find_func(rfname);
       }
 
       // Trigger FuncUndefined event, may load the function.
@@ -1588,13 +1588,13 @@ int call_func(const char *funcname, int len, typval_T *rettv, int argcount_in, t
           && apply_autocmds(EVENT_FUNCUNDEFINED, rfname, rfname, true, NULL)
           && !aborting()) {
         // executed an autocommand, search for the function again
-        fp = find_func((char_u *)rfname);
+        fp = find_func(rfname);
       }
       // Try loading a package.
       if (fp == NULL && script_autoload((const char *)rfname, strlen(rfname),
                                         true) && !aborting()) {
         // Loaded a package, search for the function again.
-        fp = find_func((char_u *)rfname);
+        fp = find_func(rfname);
       }
 
       if (fp != NULL && (fp->uf_flags & FC_DELETED)) {
@@ -2133,7 +2133,7 @@ void ex_function(exarg_T *eap)
       *p = NUL;
     }
     if (!eap->skip && !got_int) {
-      fp = find_func((char_u *)name);
+      fp = find_func(name);
       if (fp != NULL) {
         list_func_head(fp, !eap->forceit, eap->forceit);
         for (int j = 0; j < fp->uf_lines.ga_len && !got_int; j++) {
@@ -2256,7 +2256,7 @@ void ex_function(exarg_T *eap)
     if (!eap->skip && !eap->forceit) {
       if (fudi.fd_dict != NULL && fudi.fd_newkey == NULL) {
         emsg(_(e_funcdict));
-      } else if (name != NULL && find_func((char_u *)name) != NULL) {
+      } else if (name != NULL && find_func(name) != NULL) {
         emsg_funcname(e_funcexts, name);
       }
     }
@@ -2510,7 +2510,7 @@ void ex_function(exarg_T *eap)
       goto erret;
     }
 
-    fp = find_func((char_u *)name);
+    fp = find_func(name);
     if (fp != NULL) {
       // Function can be replaced with "function!" and when sourcing the
       // same script again, but only once.
@@ -2690,7 +2690,7 @@ bool translated_function_exists(const char *name)
   if (builtin_function(name, -1)) {
     return find_internal_func((char *)name) != NULL;
   }
-  return find_func((const char_u *)name) != NULL;
+  return find_func(name) != NULL;
 }
 
 /// Check whether function with the given name exists
@@ -2800,7 +2800,7 @@ void ex_delfunction(exarg_T *eap)
     return;
   }
   if (!eap->skip) {
-    fp = find_func((char_u *)name);
+    fp = find_func(name);
   }
   xfree(name);
 
@@ -2857,7 +2857,7 @@ void func_unref(char *name)
     return;
   }
 
-  fp = find_func((char_u *)name);
+  fp = find_func(name);
   if (fp == NULL && isdigit((uint8_t)(*name))) {
 #ifdef EXITFREE
     if (!entered_free_all_mem) {
@@ -2898,7 +2898,7 @@ void func_ref(char *name)
   if (name == NULL || !func_name_refcount(name)) {
     return;
   }
-  fp = find_func((char_u *)name);
+  fp = find_func(name);
   if (fp != NULL) {
     (fp->uf_refcount)++;
   } else if (isdigit((uint8_t)(*name))) {
@@ -3305,7 +3305,7 @@ void make_partial(dict_T *const selfdict, typval_T *const rettv)
                                       : rettv->vval.v_partial->pt_name;
     // Translate "s:func" to the stored function name.
     fname = fname_trans_sid(fname, fname_buf, &tofree, &error);
-    fp = find_func((char_u *)fname);
+    fp = find_func(fname);
     xfree(tofree);
   }
 
@@ -3651,7 +3651,7 @@ bool set_ref_in_func(char *name, ufunc_T *fp_in, int copyID)
 
   if (fp_in == NULL) {
     fname = fname_trans_sid(name, fname_buf, &tofree, &error);
-    fp = find_func((char_u *)fname);
+    fp = find_func(fname);
   }
   if (fp != NULL) {
     for (fc = fp->uf_scoped; fc != NULL; fc = fc->func->uf_scoped) {
diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index 6e888d9dcf..437a05f61d 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -1348,7 +1348,7 @@ static char *find_pipe(const char *cmd)
     }
     if (*p == '"') {
       inquote = !inquote;
-    } else if (rem_backslash((const char_u *)p)) {
+    } else if (rem_backslash(p)) {
       p++;
     }
   }
@@ -1420,7 +1420,7 @@ char *make_filter_cmd(char *cmd, char *itmp, char *otmp)
 #else
     // For shells that don't understand braces around commands, at least allow
     // the use of commands in a pipe.
-    xstrlcpy(buf, (char *)cmd, len);
+    xstrlcpy(buf, cmd, len);
     if (itmp != NULL) {
       // If there is a pipe, we have to put the '<' in front of it.
       // Don't do this when 'shellquote' is not empty, otherwise the
@@ -3351,11 +3351,11 @@ static int do_sub(exarg_T *eap, proftime_T timeout, long cmdpreview_ns, handle_T
         which_pat = RE_SEARCH;              // use last '/' pattern
       }
       pat = "";                   // empty search pattern
-      delimiter = (char_u)(*cmd++);                   // remember delimiter character
+      delimiter = (uint8_t)(*cmd++);                   // remember delimiter character
       has_second_delim = true;
     } else {          // find the end of the regexp
       which_pat = RE_LAST;                  // use last used regexp
-      delimiter = (char_u)(*cmd++);                   // remember delimiter character
+      delimiter = (uint8_t)(*cmd++);                   // remember delimiter character
       pat = cmd;                            // remember start of search pat
       cmd = skip_regexp_ex(cmd, delimiter, magic_isset(), &eap->arg, NULL, NULL);
       if (cmd[0] == delimiter) {            // end delimiter found
@@ -3697,7 +3697,7 @@ static int do_sub(exarg_T *eap, proftime_T timeout, long cmdpreview_ns, handle_T
               msg_putchar('\n');
               xfree(prompt);
               if (resp != NULL) {
-                typed = (char_u)(*resp);
+                typed = (uint8_t)(*resp);
                 xfree(resp);
               } else {
                 // getcmdline_prompt() returns NULL if there is no command line to return.
@@ -4704,7 +4704,7 @@ char *skip_vimgrep_pat(char *p, char **s, int *flags)
     if (s != NULL) {
       *s = p + 1;
     }
-    c = (char_u)(*p);
+    c = (uint8_t)(*p);
     p = skip_regexp(p + 1, c, true);
     if (*p != c) {
       return NULL;
diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index 08d4065e98..eefb1ae1ce 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -3710,7 +3710,7 @@ char *replace_makeprg(exarg_T *eap, char *arg, char **cmdlinep)
   if ((eap->cmdidx == CMD_make || eap->cmdidx == CMD_lmake || isgrep)
       && !grep_internal(eap->cmdidx)) {
     const char *program = isgrep ? (*curbuf->b_p_gp == NUL ? p_gp : curbuf->b_p_gp)
-                                 : (*curbuf->b_p_mp == NUL ? (char *)p_mp : curbuf->b_p_mp);
+                                 : (*curbuf->b_p_mp == NUL ? p_mp : curbuf->b_p_mp);
 
     arg = skipwhite(arg);
 
@@ -3767,8 +3767,8 @@ 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(p, (char_u *)eap->arg, &srclen, &(eap->do_ecmd_lnum),
-                                   errormsgp, &escaped, true);
+    char *repl = eval_vars(p, eap->arg, &srclen, &(eap->do_ecmd_lnum),
+                           errormsgp, &escaped, true);
     if (*errormsgp != NULL) {           // error detected
       return FAIL;
     }
@@ -3868,7 +3868,7 @@ int expand_filename(exarg_T *eap, char **cmdlinep, char **errormsgp)
       backslash_halve(eap->arg);
     }
 #else
-    backslash_halve((char_u *)eap->arg);
+    backslash_halve(eap->arg);
 #endif
 
     if (has_wildcards) {
@@ -6725,8 +6725,8 @@ 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 *src, const char_u *srcstart, size_t *usedlen, linenr_T *lnump,
-                  char **errormsg, int *escaped, bool empty_is_error)
+char *eval_vars(char *src, const char *srcstart, size_t *usedlen, linenr_T *lnump, char **errormsg,
+                int *escaped, bool empty_is_error)
 {
   char *result;
   char *resultbuf = NULL;
@@ -6750,7 +6750,7 @@ char_u *eval_vars(char *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 ((char_u *)src > srcstart && src[-1] == '\\') {
+  if (src > srcstart && src[-1] == '\\') {
     *usedlen = 0;
     STRMOVE(src - 1, (char *)src);      // remove backslash
     return NULL;
@@ -6985,7 +6985,7 @@ char_u *eval_vars(char *src, const char_u *srcstart, size_t *usedlen, linenr_T *
     result = xstrnsave(result, resultlen);
   }
   xfree(resultbuf);
-  return (char_u *)result;
+  return result;
 }
 
 /// Expand the <sfile> string in "arg".
@@ -7002,8 +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(p, (char_u *)result, &srclen, NULL, &errormsg, NULL,
-                                     true);
+      char *repl = eval_vars(p, result, &srclen, NULL, &errormsg, NULL, true);
       if (errormsg != NULL) {
         if (*errormsg) {
           emsg(errormsg);
diff --git a/src/nvim/ex_eval.c b/src/nvim/ex_eval.c
index bfbb6f89b5..f76e60f6c5 100644
--- a/src/nvim/ex_eval.c
+++ b/src/nvim/ex_eval.c
@@ -1150,7 +1150,7 @@ void ex_throw(exarg_T *eap)
   // On error or when an exception is thrown during argument evaluation, do
   // not throw.
   if (!eap->skip && value != NULL) {
-    if (throw_exception((char_u *)value, ET_USER, NULL) == FAIL) {
+    if (throw_exception(value, ET_USER, NULL) == FAIL) {
       xfree(value);
     } else {
       do_throw(eap->cstack);
diff --git a/src/nvim/file_search.c b/src/nvim/file_search.c
index 02a33f8fd3..e236f23895 100644
--- a/src/nvim/file_search.c
+++ b/src/nvim/file_search.c
@@ -143,7 +143,7 @@ typedef struct ff_visited_list_hdr {
 
 // '**' can be expanded to several directory levels.
 // Set the default maximum depth.
-#define FF_MAX_STAR_STAR_EXPAND ((char_u)30)
+#define FF_MAX_STAR_STAR_EXPAND 30
 
 // The search context:
 //   ffsc_stack_ptr:    the stack for the dirs to search
@@ -182,7 +182,7 @@ typedef struct ff_search_ctx_T {
 # include "file_search.c.generated.h"
 #endif
 
-static char_u e_pathtoolong[] = N_("E854: path too long for completion");
+static char e_pathtoolong[] = N_("E854: path too long for completion");
 
 /// Initialization routine for vim_findfile().
 ///
@@ -302,14 +302,12 @@ void *vim_findfile_init(char *path, char *filename, char *stopdirs, int level, i
 #ifdef BACKSLASH_IN_FILENAME
     // "c:dir" needs "c:" to be expanded, otherwise use current dir
     if (*path != NUL && path[1] == ':') {
-      char_u drive[3];
+      char drive[3];
 
       drive[0] = path[0];
       drive[1] = ':';
       drive[2] = NUL;
-      if (vim_FullName((const char *)drive, (char *)ff_expand_buffer, MAXPATHL,
-                       true)
-          == FAIL) {
+      if (vim_FullName(drive, ff_expand_buffer, MAXPATHL, true) == FAIL) {
         goto error_return;
       }
       path += 2;
@@ -504,15 +502,15 @@ error_return:
 }
 
 /// @return  the stopdir string.  Check that ';' is not escaped.
-char_u *vim_findfile_stopdir(char *buf)
+char *vim_findfile_stopdir(char *buf)
 {
-  char_u *r_ptr = (char_u *)buf;
+  char *r_ptr = buf;
 
   while (*r_ptr != NUL && *r_ptr != ';') {
     if (r_ptr[0] == '\\' && r_ptr[1] == ';') {
       // Overwrite the escape char,
       // use strlen(r_ptr) to move the trailing '\0'.
-      STRMOVE(r_ptr, (char *)r_ptr + 1);
+      STRMOVE(r_ptr, r_ptr + 1);
       r_ptr++;
     }
     r_ptr++;
@@ -1291,7 +1289,7 @@ char *find_file_in_path(char *ptr, size_t len, int options, int first, char *rel
 {
   return find_file_in_path_option(ptr, len, options, first,
                                   (*curbuf->b_p_path == NUL
-                                   ? (char *)p_path
+                                   ? p_path
                                    : curbuf->b_p_path),
                                   FINDFILE_BOTH, rel_fname, curbuf->b_p_sua);
 }
@@ -1324,7 +1322,7 @@ void free_findfile(void)
 /// @return  an allocated string for the file name.  NULL for error.
 char *find_directory_in_path(char *ptr, size_t len, int options, char *rel_fname)
 {
-  return find_file_in_path_option(ptr, len, options, true, (char *)p_cdpath,
+  return find_file_in_path_option(ptr, len, options, true, p_cdpath,
                                   FINDFILE_DIR, rel_fname, "");
 }
 
@@ -1469,7 +1467,7 @@ char *find_file_in_path_option(char *ptr, size_t len, int options, int first, ch
         copy_option_part(&dir, buf, MAXPATHL, " ,");
 
         // get the stopdir string
-        r_ptr = (char *)vim_findfile_stopdir(buf);
+        r_ptr = vim_findfile_stopdir(buf);
         fdip_search_ctx = vim_findfile_init(buf, ff_file_to_find,
                                             r_ptr, 100, false, find_what,
                                             fdip_search_ctx, false, rel_fname);
diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index 78fe8a3ab3..c05eb41b6d 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -1114,7 +1114,7 @@ retry:
         if (size < 2 || curbuf->b_p_bin) {
           ccname = NULL;
         } else {
-          ccname = check_for_bom((char_u *)ptr, size, &blen,
+          ccname = check_for_bom(ptr, size, &blen,
                                  fio_flags == FIO_UCSBOM ? FIO_ALL : get_fio_flags(fenc));
         }
         if (ccname != NULL) {
@@ -2473,7 +2473,7 @@ int buf_write(buf_T *buf, char *fname, char *sfname, linenr_T start, linenr_T en
   if (!filtering) {
     filemess(buf,
 #ifndef UNIX
-             (char_u *)sfname,
+             sfname,
 #else
              fname,
 #endif
@@ -2517,7 +2517,7 @@ int buf_write(buf_T *buf, char *fname, char *sfname, linenr_T start, linenr_T en
   }
 #else  // win32
   // Check for a writable device name.
-  c = fname == NULL ? NODE_OTHER : os_nodetype((char *)fname);
+  c = fname == NULL ? NODE_OTHER : os_nodetype(fname);
   if (c == NODE_OTHER) {
     SET_ERRMSG_NUM("E503", _("is not a file or writable device"));
     goto fail;
@@ -2535,7 +2535,7 @@ int buf_write(buf_T *buf, char *fname, char *sfname, linenr_T start, linenr_T en
       goto fail;
     }
     if (overwriting) {
-      os_fileinfo((char *)fname, &file_info_old);
+      os_fileinfo(fname, &file_info_old);
     }
   }
 #endif  // !UNIX
@@ -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((char *)p_bsk, sfname, ffname)) {
+  if (dobackup && *p_bsk != NUL && match_file_list(p_bsk, sfname, ffname)) {
     dobackup = false;
   }
 
@@ -4130,8 +4130,9 @@ static int get_fio_flags(const char *name)
 ///
 /// @return  the name of the encoding and set "*lenp" to the length or,
 ///          NULL when no BOM found.
-static char *check_for_bom(const char_u *p, long size, int *lenp, int flags)
+static char *check_for_bom(const char *p_in, long size, int *lenp, int flags)
 {
+  const uint8_t *p = (const uint8_t *)p_in;
   char *name = NULL;
   int len = 2;
 
@@ -4647,7 +4648,7 @@ int vim_rename(const char *from, const char *to)
     to = from;
   }
 #ifndef UNIX  // For Unix os_open() already set the permission.
-  os_setperm((const char *)to, perm);
+  os_setperm(to, perm);
 #endif
 #ifdef HAVE_ACL
   os_set_acl(to, acl);
@@ -5156,11 +5157,11 @@ void write_lnum_adjust(linenr_T offset)
 #if defined(BACKSLASH_IN_FILENAME)
 /// Convert all backslashes in fname to forward slashes in-place,
 /// unless when it looks like a URL.
-void forward_slash(char_u *fname)
+void forward_slash(char *fname)
 {
-  char_u *p;
+  char *p;
 
-  if (path_with_url((const char *)fname)) {
+  if (path_with_url(fname)) {
     return;
   }
   for (p = fname; *p != NUL; p++) {
diff --git a/src/nvim/getchar.c b/src/nvim/getchar.c
index 842b0b10b6..d993d65dc0 100644
--- a/src/nvim/getchar.c
+++ b/src/nvim/getchar.c
@@ -151,11 +151,11 @@ void free_buff(buffheader_T *buf)
 /// K_SPECIAL in the returned string is escaped.
 ///
 /// @param dozero  count == zero is not an error
-static char_u *get_buffcont(buffheader_T *buffer, int dozero)
+static char *get_buffcont(buffheader_T *buffer, int dozero)
 {
   size_t count = 0;
-  char_u *p = NULL;
-  char_u *p2;
+  char *p = NULL;
+  char *p2;
 
   // compute the total length of the string
   for (const buffblock_T *bp = buffer->bh_first.b_next;
@@ -168,7 +168,7 @@ static char_u *get_buffcont(buffheader_T *buffer, int dozero)
     p2 = p;
     for (const buffblock_T *bp = buffer->bh_first.b_next;
          bp != NULL; bp = bp->b_next) {
-      for (const char_u *str = (char_u *)bp->b_str; *str;) {
+      for (const char *str = bp->b_str; *str;) {
         *p2++ = *str++;
       }
     }
@@ -185,7 +185,7 @@ char_u *get_recorded(void)
   char *p;
   size_t len;
 
-  p = (char *)get_buffcont(&recordbuff, true);
+  p = get_buffcont(&recordbuff, true);
   free_buff(&recordbuff);
 
   // Remove the characters that were added the last time, these must be the
@@ -207,7 +207,7 @@ char_u *get_recorded(void)
 
 /// Return the contents of the redo buffer as a single string.
 /// K_SPECIAL in the returned string is escaped.
-char_u *get_inserted(void)
+char *get_inserted(void)
 {
   return get_buffcont(&redobuff, false);
 }
@@ -475,7 +475,7 @@ void saveRedobuff(save_redo_T *save_redo)
   old_redobuff.bh_first.b_next = NULL;
 
   // Make a copy, so that ":normal ." in a function works.
-  char *const s = (char *)get_buffcont(&save_redo->sr_redobuff, false);
+  char *const s = get_buffcont(&save_redo->sr_redobuff, false);
   if (s == NULL) {
     return;
   }
diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index 7da8d12f4b..df4ae05522 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -806,8 +806,8 @@ enum {
 extern char *default_vim_dir;
 extern char *default_vimruntime_dir;
 extern char *default_lib_dir;
-extern char_u *compiled_user;
-extern char_u *compiled_sys;
+extern char *compiled_user;
+extern char *compiled_sys;
 #endif
 
 // When a window has a local directory, the absolute path of the global
diff --git a/src/nvim/help.c b/src/nvim/help.c
index 91fda60859..bbc552fa4c 100644
--- a/src/nvim/help.c
+++ b/src/nvim/help.c
@@ -555,7 +555,7 @@ int find_help_tags(const char *arg, int *num_matches, char ***matches, bool keep
     // Sort the matches found on the heuristic number that is after the
     // tag name.
     qsort((void *)(*matches), (size_t)(*num_matches),
-          sizeof(char_u *), help_compare);
+          sizeof(char *), help_compare);
     // Delete more than TAG_MANY to reduce the size of the listing.
     while (*num_matches > TAG_MANY) {
       xfree((*matches)[--*num_matches]);
@@ -799,7 +799,7 @@ void fix_help_buffer(void)
                   // The text is utf-8 when a byte
                   // above 127 is found and no
                   // illegal byte sequence is found.
-                  if ((char_u)(*s) >= 0x80 && this_utf != kFalse) {
+                  if ((uint8_t)(*s) >= 0x80 && this_utf != kFalse) {
                     this_utf = kTrue;
                     const int l = utf_ptr2len(s);
                     if (l == 1) {
@@ -923,7 +923,7 @@ static void helptags_one(char *dir, const char *ext, const char *tagfname, bool
 
   // If using the "++t" argument or generating tags for "$VIMRUNTIME/doc"
   // add the "help-tags" tag.
-  ga_init(&ga, (int)sizeof(char_u *), 100);
+  ga_init(&ga, (int)sizeof(char *), 100);
   if (add_help_tags
       || path_full_compare("$VIMRUNTIME/doc", dir, false, true) == kEqualFiles) {
     size_t s_len = 18 + strlen(tagfname);
@@ -948,7 +948,7 @@ static void helptags_one(char *dir, const char *ext, const char *tagfname, bool
         // Detect utf-8 file by a non-ASCII char in the first line.
         TriState this_utf8 = kNone;
         for (s = IObuff; *s != NUL; s++) {
-          if ((char_u)(*s) >= 0x80) {
+          if ((uint8_t)(*s) >= 0x80) {
             this_utf8 = kTrue;
             const int l = utf_ptr2len(s);
             if (l == 1) {
diff --git a/src/nvim/highlight_group.c b/src/nvim/highlight_group.c
index 5f7e41e6e0..5d34b48816 100644
--- a/src/nvim/highlight_group.c
+++ b/src/nvim/highlight_group.c
@@ -1069,7 +1069,7 @@ void do_highlight(const char *line, const bool forceit, const bool init)
       }
       memcpy(key, key_start, key_len);
       key[key_len] = NUL;
-      vim_strup((char_u *)key);
+      vim_strup(key);
       linep = (const char *)skipwhite(linep);
 
       if (strcmp(key, "NONE") == 0) {
@@ -1793,7 +1793,7 @@ int syn_name2id_len(const char *name, size_t len)
   // Avoid alloc()/free(), these are slow too.
   memcpy(name_u, name, len);
   name_u[len] = '\0';
-  vim_strup((char_u *)name_u);
+  vim_strup(name_u);
 
   // map_get(..., int) returns 0 when no key is present, which is
   // the expected value for missing highlight group.
@@ -1906,7 +1906,7 @@ static int syn_add_group(const char *name, size_t len)
   hlgp->sg_parent = scoped_parent;
   // will get set to false by caller if settings are added
   hlgp->sg_cleared = true;
-  vim_strup((char_u *)hlgp->sg_name_u);
+  vim_strup(hlgp->sg_name_u);
 
   int id = highlight_ga.ga_len;  // ID is index plus one
 
diff --git a/src/nvim/insexpand.c b/src/nvim/insexpand.c
index a8af8ec966..7f81731b26 100644
--- a/src/nvim/insexpand.c
+++ b/src/nvim/insexpand.c
@@ -2951,7 +2951,7 @@ static void get_next_dict_tsr_completion(int compl_type, char *dict, int dict_f)
   } else {
     ins_compl_dictionaries(dict != NULL ? dict
                            : (compl_type == CTRL_X_THESAURUS
-                              ? (*curbuf->b_p_tsr == NUL ? (char *)p_tsr : curbuf->b_p_tsr)
+                              ? (*curbuf->b_p_tsr == NUL ? p_tsr : curbuf->b_p_tsr)
                               : (*curbuf->b_p_dict ==
                                  NUL ? p_dict : curbuf->b_p_dict)),
                            compl_pattern,
diff --git a/src/nvim/keycodes.c b/src/nvim/keycodes.c
index 552dec6bf8..e19806e464 100644
--- a/src/nvim/keycodes.c
+++ b/src/nvim/keycodes.c
@@ -474,7 +474,7 @@ char_u *get_special_key_name(int c, int modifiers)
 
   int i, idx;
   int table_idx;
-  char_u *s;
+  char *s;
 
   string[0] = '<';
   idx = 1;
@@ -541,9 +541,9 @@ char_u *get_special_key_name(int c, int modifiers)
       } else if (vim_isprintc(c)) {
         string[idx++] = (char_u)c;
       } else {
-        s = (char_u *)transchar(c);
+        s = transchar(c);
         while (*s) {
-          string[idx++] = *s++;
+          string[idx++] = (uint8_t)(*s++);
         }
       }
     }
@@ -629,11 +629,11 @@ int find_special_key(const char **const srcp, const size_t src_len, int *const m
                      const int flags, bool *const did_simplify)
   FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ARG(1, 3)
 {
-  const char_u *last_dash;
-  const char_u *end_of_name;
-  const char_u *src;
-  const char_u *bp;
-  const char_u *const end = (char_u *)(*srcp) + src_len - 1;
+  const char *last_dash;
+  const char *end_of_name;
+  const char *src;
+  const char *bp;
+  const char *const end = *srcp + src_len - 1;
   const bool in_string = flags & FSK_IN_STRING;
   int modifiers;
   int bit;
@@ -645,7 +645,7 @@ int find_special_key(const char **const srcp, const size_t src_len, int *const m
     return 0;
   }
 
-  src = (char_u *)(*srcp);
+  src = *srcp;
   if (src[0] != '<') {
     return 0;
   }
@@ -659,7 +659,7 @@ int find_special_key(const char **const srcp, const size_t src_len, int *const m
     if (*bp == '-') {
       last_dash = bp;
       if (bp + 1 <= end) {
-        l = utfc_ptr2len_len((char *)bp + 1, (int)(end - bp) + 1);
+        l = utfc_ptr2len_len(bp + 1, (int)(end - bp) + 1);
         // Anything accepted, like <C-?>.
         // <C-"> or <M-"> are not special in strings as " is
         // the string delimiter. With a backslash it works: <M-\">
@@ -674,7 +674,7 @@ int find_special_key(const char **const srcp, const size_t src_len, int *const m
     if (end - bp > 3 && bp[0] == 't' && bp[1] == '_') {
       bp += 3;  // skip t_xx, xx may be '-' or '>'
     } else if (end - bp > 4 && STRNICMP(bp, "char-", 5) == 0) {
-      vim_str2nr((char *)bp + 5, NULL, &l, STR2NR_ALL, NULL, NULL, 0, true);
+      vim_str2nr(bp + 5, NULL, &l, STR2NR_ALL, NULL, NULL, 0, true);
       if (l == 0) {
         emsg(_(e_invarg));
         return 0;
@@ -691,7 +691,7 @@ int find_special_key(const char **const srcp, const size_t src_len, int *const m
     modifiers = 0x0;
     for (bp = src + 1; bp < last_dash; bp++) {
       if (*bp != '-') {
-        bit = name_to_mod_mask(*bp);
+        bit = name_to_mod_mask((uint8_t)(*bp));
         if (bit == 0x0) {
           break;                // Illegal modifier name
         }
@@ -704,7 +704,7 @@ int find_special_key(const char **const srcp, const size_t src_len, int *const m
       if (STRNICMP(last_dash + 1, "char-", 5) == 0
           && ascii_isdigit(last_dash[6])) {
         // <Char-123> or <Char-033> or <Char-0x33>
-        vim_str2nr((char *)last_dash + 6, NULL, &l, STR2NR_ALL, NULL, &n, 0, true);
+        vim_str2nr(last_dash + 6, NULL, &l, STR2NR_ALL, NULL, &n, 0, true);
         if (l == 0) {
           emsg(_(e_invarg));
           return 0;
@@ -718,12 +718,12 @@ int find_special_key(const char **const srcp, const size_t src_len, int *const m
           // Special case for a double-quoted string
           off = l = 2;
         } else {
-          l = utfc_ptr2len((char *)last_dash + 1);
+          l = utfc_ptr2len(last_dash + 1);
         }
         if (modifiers != 0 && last_dash[l + 1] == '>') {
-          key = utf_ptr2char((char *)last_dash + off);
+          key = utf_ptr2char(last_dash + off);
         } else {
-          key = get_special_key_code(last_dash + off);
+          key = get_special_key_code((char_u *)last_dash + off);
           if (!(flags & FSK_KEEP_X_KEY)) {
             key = handle_x_keys(key);
           }
@@ -753,7 +753,7 @@ int find_special_key(const char **const srcp, const size_t src_len, int *const m
         }
 
         *modp = modifiers;
-        *srcp = (char *)end_of_name;
+        *srcp = end_of_name;
         return key;
       }  // else { ELOG("unknown key: '%s'", src); }
     }
diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index 7006c1dc4e..5ffd90fddd 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -1440,11 +1440,11 @@ int nlua_source_using_linegetter(LineGetter fgetline, void *cookie, char *name)
   estack_push(ETYPE_SCRIPT, name, 0);
 
   garray_T ga;
-  char_u *line = NULL;
+  char *line = NULL;
 
-  ga_init(&ga, (int)sizeof(char_u *), 10);
-  while ((line = (char_u *)fgetline(0, cookie, 0, false)) != NULL) {
-    GA_APPEND(char_u *, &ga, line);
+  ga_init(&ga, (int)sizeof(char *), 10);
+  while ((line = fgetline(0, cookie, 0, false)) != NULL) {
+    GA_APPEND(char *, &ga, line);
   }
   char *code = ga_concat_strings_sep(&ga, "\n");
   size_t len = strlen(code);
@@ -1877,7 +1877,7 @@ int nlua_expand_pat(expand_T *xp, char *pat, int *num_results, char ***results)
       goto cleanup_array;
     }
 
-    GA_APPEND(char_u *, &result_array, (char_u *)string_to_cstr(v.data.string));
+    GA_APPEND(char *, &result_array, string_to_cstr(v.data.string));
   }
 
   xp->xp_pattern += prefix_len;
@@ -1914,7 +1914,7 @@ bool nlua_is_table_from_lua(const typval_T *const arg)
   }
 }
 
-char_u *nlua_register_table_as_callable(const typval_T *const arg)
+char *nlua_register_table_as_callable(const typval_T *const arg)
 {
   LuaRef table_ref = LUA_NOREF;
   if (arg->v_type == VAR_DICT) {
@@ -1950,7 +1950,7 @@ char_u *nlua_register_table_as_callable(const typval_T *const arg)
 
   LuaRef func = nlua_ref_global(lstate, -1);
 
-  char_u *name = (char_u *)register_luafunc(func);
+  char *name = register_luafunc(func);
 
   lua_pop(lstate, 1);  // []
   assert(top == lua_gettop(lstate));
@@ -1960,8 +1960,8 @@ char_u *nlua_register_table_as_callable(const typval_T *const arg)
 
 void nlua_execute_on_key(int c)
 {
-  char_u buf[NUMBUFLEN];
-  size_t buf_len = special_to_buf(c, mod_mask, false, buf);
+  char buf[NUMBUFLEN];
+  size_t buf_len = special_to_buf(c, mod_mask, false, (char_u *)buf);
 
   lua_State *const lstate = global_lstate;
 
@@ -1977,7 +1977,7 @@ void nlua_execute_on_key(int c)
   luaL_checktype(lstate, -1, LUA_TFUNCTION);
 
   // [ vim, vim._on_key, buf ]
-  lua_pushlstring(lstate, (const char *)buf, buf_len);
+  lua_pushlstring(lstate, buf, buf_len);
 
   int save_got_int = got_int;
   got_int = false;  // avoid interrupts when the key typed is Ctrl-C
diff --git a/src/nvim/main.c b/src/nvim/main.c
index 4dfb00f2db..62af56e972 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -765,7 +765,7 @@ void getout(int exitval)
 
   // Apply 'titleold'.
   if (p_title && *p_titleold != NUL) {
-    ui_call_set_title(cstr_as_string((char *)p_titleold));
+    ui_call_set_title(cstr_as_string(p_titleold));
   }
 
   if (garbage_collect_at_exit) {
@@ -1509,7 +1509,7 @@ static void handle_quickfix(mparm_T *paramp)
       set_string_option_direct("ef", -1, paramp->use_ef, OPT_FREE, SID_CARG);
     }
     vim_snprintf(IObuff, IOSIZE, "cfile %s", p_ef);
-    if (qf_init(NULL, (char *)p_ef, p_efm, true, IObuff, p_menc) < 0) {
+    if (qf_init(NULL, p_ef, p_efm, true, IObuff, p_menc) < 0) {
       msg_putchar('\n');
       os_exit(3);
     }
diff --git a/src/nvim/mbyte.c b/src/nvim/mbyte.c
index 63f3b02feb..441bbc4b58 100644
--- a/src/nvim/mbyte.c
+++ b/src/nvim/mbyte.c
@@ -406,9 +406,9 @@ int bomb_size(void)
 }
 
 // Remove all BOM from "s" by moving remaining text.
-void remove_bom(char_u *s)
+void remove_bom(char *s)
 {
-  char *p = (char *)s;
+  char *p = s;
 
   while ((p = strchr(p, 0xef)) != NULL) {
     if ((uint8_t)p[1] == 0xbb && (uint8_t)p[2] == 0xbf) {
@@ -566,8 +566,8 @@ size_t mb_string2cells(const char *str)
 {
   size_t clen = 0;
 
-  for (const char_u *p = (char_u *)str; *p != NUL; p += utfc_ptr2len((char *)p)) {
-    clen += (size_t)utf_ptr2cells((char *)p);
+  for (const char *p = str; *p != NUL; p += utfc_ptr2len(p)) {
+    clen += (size_t)utf_ptr2cells(p);
   }
 
   return clen;
@@ -1534,14 +1534,14 @@ void show_utf8(void)
 {
   int len;
   int rlen = 0;
-  char_u *line;
+  char *line;
   int clen;
   int i;
 
   // Get the byte length of the char under the cursor, including composing
   // characters.
-  line = (char_u *)get_cursor_pos_ptr();
-  len = utfc_ptr2len((char *)line);
+  line = get_cursor_pos_ptr();
+  len = utfc_ptr2len(line);
   if (len == 0) {
     msg("NUL");
     return;
@@ -1555,10 +1555,10 @@ void show_utf8(void)
         STRCPY(IObuff + rlen, "+ ");
         rlen += 2;
       }
-      clen = utf_ptr2len((char *)line + i);
+      clen = utf_ptr2len(line + i);
     }
     sprintf(IObuff + rlen, "%02x ",  // NOLINT(runtime/printf)
-            (line[i] == NL) ? NUL : line[i]);          // NUL is stored as NL
+            (line[i] == NL) ? NUL : (uint8_t)line[i]);          // NUL is stored as NL
     clen--;
     rlen += (int)strlen(IObuff + rlen);
     if (rlen > IOSIZE - 20) {
@@ -1884,7 +1884,7 @@ void utf_find_illegal(void)
   char *p;
   int len;
   vimconv_T vimconv;
-  char_u *tofree = NULL;
+  char *tofree = NULL;
 
   vimconv.vc_type = CONV_NONE;
   if (enc_canon_props(curbuf->b_p_fenc) & ENC_8BIT) {
@@ -1899,11 +1899,11 @@ void utf_find_illegal(void)
     p = get_cursor_pos_ptr();
     if (vimconv.vc_type != CONV_NONE) {
       xfree(tofree);
-      tofree = (char_u *)string_convert(&vimconv, p, NULL);
+      tofree = string_convert(&vimconv, p, NULL);
       if (tofree == NULL) {
         break;
       }
-      p = (char *)tofree;
+      p = tofree;
     }
 
     while (*p != NUL) {
@@ -1916,7 +1916,7 @@ void utf_find_illegal(void)
         } else {
           int l;
 
-          len = (int)(p - (char *)tofree);
+          len = (int)(p - tofree);
           for (p = get_cursor_pos_ptr(); *p != NUL && len-- > 0; p += l) {
             l = utf_ptr2len(p);
             curwin->w_cursor.col += l;
@@ -2024,7 +2024,7 @@ char *mb_prevptr(char *line, char *p)
 /// following composing characters) counts as one.
 int mb_charlen(const char *str)
 {
-  const char_u *p = (char_u *)str;
+  const char *p = str;
   int count;
 
   if (p == NULL) {
@@ -2032,20 +2032,20 @@ int mb_charlen(const char *str)
   }
 
   for (count = 0; *p != NUL; count++) {
-    p += utfc_ptr2len((char *)p);
+    p += utfc_ptr2len(p);
   }
 
   return count;
 }
 
 /// Like mb_charlen() but for a string with specified length.
-int mb_charlen_len(const char_u *str, int len)
+int mb_charlen_len(const char *str, int len)
 {
-  const char_u *p = str;
+  const char *p = str;
   int count;
 
   for (count = 0; *p != NUL && p < str + len; count++) {
-    p += utfc_ptr2len((char *)p);
+    p += utfc_ptr2len(p);
   }
 
   return count;
@@ -2196,7 +2196,7 @@ static int enc_alias_search(const char *name)
 
 // Get the canonicalized encoding of the current locale.
 // Returns an allocated string when successful, NULL when not.
-char_u *enc_locale(void)
+char *enc_locale(void)
 {
   int i;
   char buf[50];
@@ -2256,7 +2256,7 @@ enc_locale_copy_enc:
     buf[i] = NUL;
   }
 
-  return (char_u *)enc_canonize(buf);
+  return enc_canonize(buf);
 }
 
 #if defined(HAVE_ICONV)
@@ -2269,7 +2269,7 @@ void *my_iconv_open(char *to, char *from)
 {
   iconv_t fd;
 # define ICONV_TESTLEN 400
-  char_u tobuf[ICONV_TESTLEN];
+  char tobuf[ICONV_TESTLEN];
   char *p;
   size_t tolen;
   static WorkingStatus iconv_working = kUnknown;
@@ -2285,7 +2285,7 @@ void *my_iconv_open(char *to, char *from)
     // because it's wide-spread.  The symptoms are that after outputting
     // the initial shift state the "to" pointer is NULL and conversion
     // stops for no apparent reason after about 8160 characters.
-    p = (char *)tobuf;
+    p = tobuf;
     tolen = ICONV_TESTLEN;
     (void)iconv(fd, NULL, NULL, &p, &tolen);
     if (p == NULL) {
@@ -2305,8 +2305,8 @@ void *my_iconv_open(char *to, char *from)
 // sequence and set "*unconvlenp" to the length of it.
 // Returns the converted string in allocated memory.  NULL for an error.
 // If resultlenp is not NULL, sets it to the result length in bytes.
-static char_u *iconv_string(const vimconv_T *const vcp, const char_u *str, size_t slen,
-                            size_t *unconvlenp, size_t *resultlenp)
+static char *iconv_string(const vimconv_T *const vcp, const char *str, size_t slen,
+                          size_t *unconvlenp, size_t *resultlenp)
 {
   const char *from;
   size_t fromlen;
@@ -2314,11 +2314,11 @@ static char_u *iconv_string(const vimconv_T *const vcp, const char_u *str, size_
   size_t tolen;
   size_t len = 0;
   size_t done = 0;
-  char_u *result = NULL;
-  char_u *p;
+  char *result = NULL;
+  char *p;
   int l;
 
-  from = (char *)str;
+  from = str;
   fromlen = slen;
   for (;;) {
     if (len == 0 || ICONV_ERRNO == ICONV_E2BIG) {
@@ -2333,7 +2333,7 @@ static char_u *iconv_string(const vimconv_T *const vcp, const char_u *str, size_
       result = p;
     }
 
-    to = (char *)result + done;
+    to = result + done;
     tolen = len - done - 2;
     // Avoid a warning for systems with a wrong iconv() prototype by
     // casting the second argument to void *.
@@ -2373,11 +2373,11 @@ static char_u *iconv_string(const vimconv_T *const vcp, const char_u *str, size_
       break;
     }
     // Not enough room or skipping illegal sequence.
-    done = (size_t)(to - (char *)result);
+    done = (size_t)(to - result);
   }
 
   if (resultlenp != NULL && result != NULL) {
-    *resultlenp = (size_t)(to - (char *)result);
+    *resultlenp = (size_t)(to - result);
   }
   return result;
 }
@@ -2474,14 +2474,13 @@ int convert_setup_ext(vimconv_T *vcp, char *from, bool from_unicode_is_utf8, cha
 /// When something goes wrong, NULL is returned and "*lenp" is unchanged.
 char *string_convert(const vimconv_T *const vcp, char *ptr, size_t *lenp)
 {
-  return (char *)string_convert_ext(vcp, (char_u *)ptr, lenp, NULL);
+  return string_convert_ext(vcp, ptr, lenp, NULL);
 }
 
 // Like string_convert(), but when "unconvlenp" is not NULL and there are is
 // an incomplete sequence at the end it is not converted and "*unconvlenp" is
 // set to the number of remaining bytes.
-char_u *string_convert_ext(const vimconv_T *const vcp, char_u *ptr, size_t *lenp,
-                           size_t *unconvlenp)
+char *string_convert_ext(const vimconv_T *const vcp, char *ptr, size_t *lenp, size_t *unconvlenp)
 {
   char_u *retval = NULL;
   char_u *d;
@@ -2490,12 +2489,12 @@ char_u *string_convert_ext(const vimconv_T *const vcp, char_u *ptr, size_t *lenp
 
   size_t len;
   if (lenp == NULL) {
-    len = strlen((char *)ptr);
+    len = strlen(ptr);
   } else {
     len = *lenp;
   }
   if (len == 0) {
-    return (char_u *)xstrdup("");
+    return xstrdup("");
   }
 
   switch (vcp->vc_type) {
@@ -2503,7 +2502,7 @@ char_u *string_convert_ext(const vimconv_T *const vcp, char_u *ptr, size_t *lenp
     retval = xmalloc(len * 2 + 1);
     d = retval;
     for (size_t i = 0; i < len; i++) {
-      c = ptr[i];
+      c = (uint8_t)ptr[i];
       if (c < 0x80) {
         *d++ = (char_u)c;
       } else {
@@ -2521,7 +2520,7 @@ char_u *string_convert_ext(const vimconv_T *const vcp, char_u *ptr, size_t *lenp
     retval = xmalloc(len * 3 + 1);
     d = retval;
     for (size_t i = 0; i < len; i++) {
-      c = ptr[i];
+      c = (uint8_t)ptr[i];
       switch (c) {
       case 0xa4:
         c = 0x20ac; break;                 // euro
@@ -2553,11 +2552,11 @@ char_u *string_convert_ext(const vimconv_T *const vcp, char_u *ptr, size_t *lenp
     retval = xmalloc(len + 1);
     d = retval;
     for (size_t i = 0; i < len; i++) {
-      l = utf_ptr2len_len((char *)ptr + i, (int)(len - i));
+      l = utf_ptr2len_len(ptr + i, (int)(len - i));
       if (l == 0) {
         *d++ = NUL;
       } else if (l == 1) {
-        uint8_t l_w = utf8len_tab_zero[ptr[i]];
+        uint8_t l_w = utf8len_tab_zero[(uint8_t)ptr[i]];
 
         if (l_w == 0) {
           // Illegal utf-8 byte cannot be converted
@@ -2569,9 +2568,9 @@ char_u *string_convert_ext(const vimconv_T *const vcp, char_u *ptr, size_t *lenp
           *unconvlenp = len - i;
           break;
         }
-        *d++ = ptr[i];
+        *d++ = (uint8_t)ptr[i];
       } else {
-        c = utf_ptr2char((char *)ptr + i);
+        c = utf_ptr2char(ptr + i);
         if (vcp->vc_type == CONV_TO_LATIN9) {
           switch (c) {
           case 0x20ac:
@@ -2625,12 +2624,12 @@ char_u *string_convert_ext(const vimconv_T *const vcp, char_u *ptr, size_t *lenp
 
 #ifdef HAVE_ICONV
   case CONV_ICONV:  // conversion with vcp->vc_fd
-    retval = iconv_string(vcp, ptr, len, unconvlenp, lenp);
+    retval = (char_u *)iconv_string(vcp, ptr, len, unconvlenp, lenp);
     break;
 #endif
   }
 
-  return retval;
+  return (char *)retval;
 }
 
 /// Table set by setcellwidths().
diff --git a/src/nvim/normal.c b/src/nvim/normal.c
index 798ea4f990..58a18ca5a8 100644
--- a/src/nvim/normal.c
+++ b/src/nvim/normal.c
@@ -3474,7 +3474,7 @@ static void nv_ident(cmdarg_T *cap)
   // Allocate buffer to put the command in.  Inserting backslashes can
   // double the length of the word.  p_kp / curbuf->b_p_kp could be added
   // and some numbers.
-  char *kp = *curbuf->b_p_kp == NUL ? (char *)p_kp : curbuf->b_p_kp;  // 'keywordprg'
+  char *kp = *curbuf->b_p_kp == NUL ? p_kp : curbuf->b_p_kp;  // 'keywordprg'
   bool kp_help = (*kp == NUL || strcmp(kp, ":he") == 0 || strcmp(kp, ":help") == 0);
   if (kp_help && *skipwhite(ptr) == NUL) {
     emsg(_(e_noident));   // found white space only
diff --git a/src/nvim/ops.c b/src/nvim/ops.c
index e08cd082d9..ac4116095f 100644
--- a/src/nvim/ops.c
+++ b/src/nvim/ops.c
@@ -5222,12 +5222,11 @@ static void str_to_reg(yankreg_T *y_ptr, MotionType yank_type, const char *str,
     }
   } else {
     size_t line_len;
-    for (const char_u *start = (char_u *)str, *end = (char_u *)str + len;
+    for (const char *start = str, *end = str + len;
          start < end + extraline;
          start += line_len + 1, lnum++) {
       assert(end - start >= 0);
-      line_len = (size_t)((char_u *)xmemscan(start, '\n',
-                                             (size_t)(end - start)) - start);
+      line_len = (size_t)((char *)xmemscan(start, '\n', (size_t)(end - start)) - start);
       if (line_len > maxlen) {
         maxlen = line_len;
       }
diff --git a/src/nvim/option.c b/src/nvim/option.c
index 2bd3dcfe2d..268a1514c8 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -381,12 +381,12 @@ void set_init_1(bool clean_arg)
   // enc_locale() will try to find the encoding of the current locale.
   // This will be used when 'default' is used as encoding specifier
   // in 'fileencodings'
-  char_u *p = enc_locale();
+  char *p = enc_locale();
   if (p == NULL) {
     // use utf-8 as 'default' if locale encoding can't be detected.
-    p = (char_u *)xmemdupz(S_LEN("utf-8"));
+    p = xmemdupz(S_LEN("utf-8"));
   }
-  fenc_default = (char *)p;
+  fenc_default = p;
 
 #ifdef HAVE_WORKING_LIBINTL
   // GNU gettext 0.10.37 supports this feature: set the codeset used for
@@ -1654,7 +1654,7 @@ static char *option_expand(int opt_idx, char *val)
   // names.
   // For 'spellsuggest' expand after "file:".
   expand_env_esc(val, NameBuff, MAXPATHL,
-                 (char_u **)options[opt_idx].var == &p_tags, false,
+                 (char **)options[opt_idx].var == &p_tags, false,
                  (char_u **)options[opt_idx].var == (char_u **)&p_sps ? "file:" :
                  NULL);
   if (strcmp(NameBuff, val) == 0) {   // they are the same
@@ -4034,12 +4034,12 @@ static char_u *get_varp(vimoption_T *p)
 }
 
 /// Get the value of 'equalprg', either the buffer-local one or the global one.
-char_u *get_equalprg(void)
+char *get_equalprg(void)
 {
   if (*curbuf->b_p_ep == NUL) {
     return p_ep;
   }
-  return (char_u *)curbuf->b_p_ep;
+  return curbuf->b_p_ep;
 }
 
 /// Copy options from one window to another.
@@ -4225,7 +4225,7 @@ static void init_buf_opt_idx(void)
 void buf_copy_options(buf_T *buf, int flags)
 {
   int should_copy = true;
-  char_u *save_p_isk = NULL;           // init for GCC
+  char *save_p_isk = NULL;           // init for GCC
   int did_isk = false;
 
   // Skip this when the option defaults have not been set yet.  Happens when
@@ -4258,7 +4258,7 @@ void buf_copy_options(buf_T *buf, int flags)
       // (jumping back to a help file with CTRL-T or CTRL-O)
       bool dont_do_help = ((flags & BCO_NOHELP) && buf->b_help) || buf->b_p_initialized;
       if (dont_do_help) {               // don't free b_p_isk
-        save_p_isk = (char_u *)buf->b_p_isk;
+        save_p_isk = buf->b_p_isk;
         buf->b_p_isk = NULL;
       }
       // Always free the allocated strings.  If not already initialized,
@@ -4453,7 +4453,7 @@ void buf_copy_options(buf_T *buf, int flags)
       // Don't touch these at all when BCO_NOHELP is used and going from
       // or to a help buffer.
       if (dont_do_help) {
-        buf->b_p_isk = (char *)save_p_isk;
+        buf->b_p_isk = save_p_isk;
         if (p_vts && p_vts != empty_option && !buf->b_p_vts_array) {
           (void)tabstop_set(p_vts, &buf->b_p_vts_array);
         } else {
@@ -4843,7 +4843,7 @@ void ExpandOldSetting(int *num_file, char ***file)
 
   // A backslash is required before some characters.  This is the reverse of
   // what happens in do_set().
-  char_u *buf = (char_u *)vim_strsave_escaped(var, escape_chars);
+  char *buf = vim_strsave_escaped(var, escape_chars);
 
 #ifdef BACKSLASH_IN_FILENAME
   // For MS-Windows et al. we don't double backslashes at the start and
@@ -4859,7 +4859,7 @@ void ExpandOldSetting(int *num_file, char ***file)
   }
 #endif
 
-  *file[0] = (char *)buf;
+  *file[0] = buf;
   *num_file = 1;
 }
 
diff --git a/src/nvim/option_defs.h b/src/nvim/option_defs.h
index e33e57424b..d190fc5999 100644
--- a/src/nvim/option_defs.h
+++ b/src/nvim/option_defs.h
@@ -442,7 +442,7 @@ EXTERN unsigned bo_flags;
 #define BO_SPELL  0x20000
 #define BO_WILD   0x40000
 
-EXTERN char_u *p_bsk;         // 'backupskip'
+EXTERN char *p_bsk;           // 'backupskip'
 EXTERN char *p_breakat;       // 'breakat'
 EXTERN char *p_bh;            ///< 'bufhidden'
 EXTERN char *p_bt;            ///< 'buftype'
@@ -468,7 +468,7 @@ EXTERN long p_columns;          // 'columns'
 EXTERN int p_confirm;           // 'confirm'
 EXTERN char *p_cot;             // 'completeopt'
 #ifdef BACKSLASH_IN_FILENAME
-EXTERN char_u *p_csl;         // 'completeslash'
+EXTERN char *p_csl;             // 'completeslash'
 #endif
 EXTERN long p_pb;               // 'pumblend'
 EXTERN long p_ph;               // 'pumheight'
@@ -494,9 +494,9 @@ EXTERN int p_ed;                // 'edcompatible'
 EXTERN char *p_ead;             // 'eadirection'
 EXTERN int p_emoji;             // 'emoji'
 EXTERN int p_ea;                // 'equalalways'
-EXTERN char_u *p_ep;            // 'equalprg'
+EXTERN char *p_ep;              // 'equalprg'
 EXTERN int p_eb;                // 'errorbells'
-EXTERN char_u *p_ef;            // 'errorfile'
+EXTERN char *p_ef;              // 'errorfile'
 EXTERN char *p_efm;             // 'errorformat'
 EXTERN char *p_gefm;            // 'grepformat'
 EXTERN char *p_gp;              // 'grepprg'
@@ -531,12 +531,12 @@ EXTERN unsigned fdo_flags;
 EXTERN char *p_fex;             ///< 'formatexpr'
 EXTERN char *p_flp;             ///< 'formatlistpat'
 EXTERN char *p_fo;              ///< 'formatoptions'
-EXTERN char_u *p_fp;            // 'formatprg'
+EXTERN char *p_fp;              // 'formatprg'
 EXTERN int p_fs;                // 'fsync'
 EXTERN int p_gd;                // 'gdefault'
 EXTERN char *p_guicursor;       // 'guicursor'
-EXTERN char_u *p_guifont;       // 'guifont'
-EXTERN char_u *p_guifontwide;   // 'guifontwide'
+EXTERN char *p_guifont;         // 'guifont'
+EXTERN char *p_guifontwide;     // 'guifontwide'
 EXTERN char *p_hf;              // 'helpfile'
 EXTERN long p_hh;               // 'helpheight'
 EXTERN char *p_hlg;             // 'helplang'
@@ -568,12 +568,12 @@ EXTERN unsigned jop_flags;
 #define JOP_STACK               0x01
 #define JOP_VIEW                0x02
 EXTERN char *p_keymap;          ///< 'keymap'
-EXTERN char_u *p_kp;            // 'keywordprg'
+EXTERN char *p_kp;              // 'keywordprg'
 EXTERN char *p_km;              // 'keymodel'
 EXTERN char *p_langmap;         // 'langmap'
 EXTERN int p_lnr;               // 'langnoremap'
 EXTERN int p_lrm;               // 'langremap'
-EXTERN char_u *p_lm;            // 'langmenu'
+EXTERN char *p_lm;              // 'langmenu'
 EXTERN long p_lines;            // 'lines'
 EXTERN long p_linespace;        // 'linespace'
 EXTERN int p_lisp;              ///< 'lisp'
@@ -588,7 +588,7 @@ EXTERN int p_lpl;               // 'loadplugins'
 EXTERN int p_magic;             // 'magic'
 EXTERN char *p_menc;            // 'makeencoding'
 EXTERN char *p_mef;             // 'makeef'
-EXTERN char_u *p_mp;            // 'makeprg'
+EXTERN char *p_mp;              // 'makeprg'
 EXTERN char *p_mps;             ///< 'matchpairs'
 EXTERN long p_mat;              // 'matchtime'
 EXTERN long p_mco;              // 'maxcombine'
@@ -613,13 +613,13 @@ EXTERN long p_mouset;           // 'mousetime'
 EXTERN int p_more;              // 'more'
 EXTERN char *p_nf;              ///< 'nrformats'
 EXTERN char *p_opfunc;          // 'operatorfunc'
-EXTERN char_u *p_para;          // 'paragraphs'
+EXTERN char *p_para;            // 'paragraphs'
 EXTERN int p_paste;             // 'paste'
 EXTERN char *p_pt;              // 'pastetoggle'
 EXTERN char *p_pex;             // 'patchexpr'
 EXTERN char *p_pm;              // 'patchmode'
-EXTERN char_u *p_path;          // 'path'
-EXTERN char_u *p_cdpath;        // 'cdpath'
+EXTERN char *p_path;            // 'path'
+EXTERN char *p_cdpath;          // 'cdpath'
 EXTERN int p_pi;                ///< 'preserveindent'
 EXTERN long p_pyx;              // 'pyxversion'
 EXTERN char *p_qe;              ///< 'quoteescape'
@@ -673,11 +673,11 @@ EXTERN unsigned ssop_flags;
 #define SSOP_SKIP_RTP          0x20000
 
 EXTERN char *p_sh;              // 'shell'
-EXTERN char_u *p_shcf;          // 'shellcmdflag'
+EXTERN char *p_shcf;            // 'shellcmdflag'
 EXTERN char *p_sp;              // 'shellpipe'
 EXTERN char *p_shq;             // 'shellquote'
 EXTERN char *p_sxq;             // 'shellxquote'
-EXTERN char_u *p_sxe;           // 'shellxescape'
+EXTERN char *p_sxe;             // 'shellxescape'
 EXTERN char *p_srr;             // 'shellredir'
 EXTERN int p_stmp;              // 'shelltemp'
 #ifdef BACKSLASH_IN_FILENAME
@@ -725,7 +725,7 @@ EXTERN unsigned int spo_flags;
 EXTERN char *p_sps;             // 'spellsuggest'
 EXTERN int p_spr;               // 'splitright'
 EXTERN int p_sol;               // 'startofline'
-EXTERN char_u *p_su;            // 'suffixes'
+EXTERN char *p_su;              // 'suffixes'
 EXTERN char *p_swb;             // 'switchbuf'
 EXTERN unsigned swb_flags;
 // Keep in sync with p_swb_values in optionstr.c
@@ -747,7 +747,7 @@ EXTERN unsigned tc_flags;       ///< flags from 'tagcase'
 #define TC_SMART                0x10
 EXTERN long p_tl;               ///< 'taglength'
 EXTERN int p_tr;                ///< 'tagrelative'
-EXTERN char_u *p_tags;          ///< 'tags'
+EXTERN char *p_tags;            ///< 'tags'
 EXTERN int p_tgst;              ///< 'tagstack'
 EXTERN int p_tbidi;             ///< 'termbidi'
 EXTERN long p_tw;               ///< 'textwidth'
@@ -756,13 +756,13 @@ EXTERN int p_timeout;           ///< 'timeout'
 EXTERN long p_tm;               ///< 'timeoutlen'
 EXTERN int p_title;             ///< 'title'
 EXTERN long p_titlelen;         ///< 'titlelen'
-EXTERN char_u *p_titleold;      ///< 'titleold'
+EXTERN char *p_titleold;        ///< 'titleold'
 EXTERN char *p_titlestring;     ///< 'titlestring'
-EXTERN char_u *p_tsr;           ///< 'thesaurus'
+EXTERN char *p_tsr;             ///< 'thesaurus'
 EXTERN int p_tgc;               ///< 'termguicolors'
 EXTERN int p_ttimeout;          ///< 'ttimeout'
 EXTERN long p_ttm;              ///< 'ttimeoutlen'
-EXTERN char_u *p_udir;          ///< 'undodir'
+EXTERN char *p_udir;            ///< 'undodir'
 EXTERN int p_udf;               ///< 'undofile'
 EXTERN long p_ul;               ///< 'undolevels'
 EXTERN long p_ur;               ///< 'undoreload'
@@ -778,15 +778,15 @@ EXTERN unsigned vop_flags;      ///< uses SSOP_ flags
 EXTERN int p_vb;                ///< 'visualbell'
 EXTERN char *p_ve;              ///< 'virtualedit'
 EXTERN unsigned ve_flags;
-#define VE_BLOCK       5U      // includes "all"
-#define VE_INSERT      6U      // includes "all"
+#define VE_BLOCK       5U       // includes "all"
+#define VE_INSERT      6U       // includes "all"
 #define VE_ALL         4U
 #define VE_ONEMORE     8U
-#define VE_NONE        16U     // "none"
-#define VE_NONEU       32U     // "NONE"
+#define VE_NONE        16U      // "none"
+#define VE_NONEU       32U      // "NONE"
 EXTERN long p_verbose;          // 'verbose'
 #ifdef IN_OPTION_C
-char_u *p_vfile = (char_u *)"";   // used before options are initialized
+char *p_vfile = "";             // used before options are initialized
 #else
 extern char *p_vfile;           // 'verbosefile'
 #endif
diff --git a/src/nvim/os/env.c b/src/nvim/os/env.c
index 7e4710a2f7..0611de14aa 100644
--- a/src/nvim/os/env.c
+++ b/src/nvim/os/env.c
@@ -689,7 +689,7 @@ void expand_env_esc(char *restrict srcp, char *restrict dst, int dstlen, bool es
 #else
         // cannot expand user's home directory, so don't try
         var = NULL;
-        tail = (char_u *)"";  // for gcc
+        tail = "";  // for gcc
 #endif  // UNIX
       }
 
@@ -697,7 +697,7 @@ void expand_env_esc(char *restrict srcp, char *restrict dst, int dstlen, bool es
       // If 'shellslash' is set change backslashes to forward slashes.
       // Can't use slash_adjust(), p_ssl may be set temporarily.
       if (p_ssl && var != NULL && vim_strchr(var, '\\') != NULL) {
-        char_u *p = xstrdup(var);
+        char *p = xstrdup(var);
 
         if (mustfree) {
           xfree(var);
diff --git a/src/nvim/os/shell.c b/src/nvim/os/shell.c
index ac8a141bbe..f1e2c5440f 100644
--- a/src/nvim/os/shell.c
+++ b/src/nvim/os/shell.c
@@ -570,7 +570,7 @@ notfound:
 char **shell_build_argv(const char *cmd, const char *extra_args)
   FUNC_ATTR_NONNULL_RET
 {
-  size_t argc = tokenize(p_sh, NULL) + (cmd ? tokenize((char *)p_shcf, NULL) : 0);
+  size_t argc = tokenize(p_sh, NULL) + (cmd ? tokenize(p_shcf, NULL) : 0);
   char **rv = xmalloc((argc + 4) * sizeof(*rv));
 
   // Split 'shell'
@@ -581,7 +581,7 @@ char **shell_build_argv(const char *cmd, const char *extra_args)
   }
 
   if (cmd) {
-    i += tokenize((char *)p_shcf, rv + i);        // Split 'shellcmdflag'
+    i += tokenize(p_shcf, rv + i);        // Split 'shellcmdflag'
     rv[i++] = shell_xescape_xquote(cmd);  // Copy (and escape) `cmd`.
   }
 
@@ -1332,7 +1332,7 @@ static char *shell_xescape_xquote(const char *cmd)
 
   const char *ecmd = cmd;
   if (*p_sxe != NUL && strcmp(p_sxq, "(") == 0) {
-    ecmd = vim_strsave_escaped_ext(cmd, (char *)p_sxe, '^', false);
+    ecmd = vim_strsave_escaped_ext(cmd, p_sxe, '^', false);
   }
   size_t ncmd_size = strlen(ecmd) + strlen(p_sxq) * 2 + 1;
   char *ncmd = xmalloc(ncmd_size);
diff --git a/src/nvim/path.c b/src/nvim/path.c
index 12087d52bd..513f366a27 100644
--- a/src/nvim/path.c
+++ b/src/nvim/path.c
@@ -229,7 +229,7 @@ char *get_past_head(const char *path)
 
 #ifdef MSWIN
   // May skip "c:"
-  if (is_path_head((char_u *)path)) {
+  if (is_path_head(path)) {
     retval = path + 2;
   }
 #endif
@@ -842,7 +842,7 @@ static bool is_unique(char *maybe_unique, garray_T *gap, int i)
 // expanding each into their equivalent path(s).
 static void expand_path_option(char *curdir, garray_T *gap)
 {
-  char *path_option = *curbuf->b_p_path == NUL ? (char *)p_path : curbuf->b_p_path;
+  char *path_option = *curbuf->b_p_path == NUL ? p_path : curbuf->b_p_path;
   char *buf = xmalloc(MAXPATHL);
 
   while (*path_option != NUL) {
@@ -1461,7 +1461,7 @@ void addfile(garray_T *gap, char *f, int flags)
 
 #ifdef FNAME_ILLEGAL
   // if the file/dir contains illegal characters, don't add it
-  if (strpbrk((char *)f, FNAME_ILLEGAL) != NULL) {
+  if (strpbrk(f, FNAME_ILLEGAL) != NULL) {
     return;
   }
 #endif
@@ -1824,7 +1824,7 @@ int vim_FullName(const char *fname, char *buf, size_t len, bool force)
   if (strlen(fname) > (len - 1)) {
     xstrlcpy(buf, fname, len);  // truncate
 #ifdef MSWIN
-    slash_adjust((char_u *)buf);
+    slash_adjust(buf);
 #endif
     return FAIL;
   }
@@ -1839,7 +1839,7 @@ int vim_FullName(const char *fname, char *buf, size_t len, bool force)
     xstrlcpy(buf, fname, len);  // something failed; use the filename
   }
 #ifdef MSWIN
-  slash_adjust((char_u *)buf);
+  slash_adjust(buf);
 #endif
   return rv;
 }
@@ -1859,7 +1859,7 @@ char *fix_fname(const char *fname)
 #ifdef UNIX
   return FullName_save(fname, true);
 #else
-  if (!vim_isAbsName((char_u *)fname)
+  if (!vim_isAbsName((char *)fname)
       || strstr(fname, "..") != NULL
       || strstr(fname, "//") != NULL
 # ifdef BACKSLASH_IN_FILENAME
@@ -2124,9 +2124,9 @@ int expand_wildcards_eval(char **pat, int *num_file, char ***file, int flags)
 
   if (is_cur_alt_file || *exp_pat == '<') {
     emsg_off++;
-    eval_pat = (char *)eval_vars(exp_pat, (char_u *)exp_pat, &usedlen, NULL, &ignored_msg,
-                                 NULL,
-                                 true);
+    eval_pat = eval_vars(exp_pat, exp_pat, &usedlen, NULL, &ignored_msg,
+                         NULL,
+                         true);
     emsg_off--;
     if (eval_pat != NULL) {
       star_follows = strcmp(exp_pat + usedlen, "*") == 0;
@@ -2241,7 +2241,7 @@ int match_suffix(char *fname)
 
   size_t fnamelen = strlen(fname);
   size_t setsuflen = 0;
-  for (char *setsuf = (char *)p_su; *setsuf;) {
+  for (char *setsuf = p_su; *setsuf;) {
     setsuflen = copy_option_part(&setsuf, suf_buf, MAXSUFLEN, ".,");
     if (setsuflen == 0) {
       char *tail = path_tail(fname);
diff --git a/src/nvim/quickfix.c b/src/nvim/quickfix.c
index 58a7379b63..44daefddc7 100644
--- a/src/nvim/quickfix.c
+++ b/src/nvim/quickfix.c
@@ -868,7 +868,7 @@ static int qf_get_nextline(qfstate_T *state)
 #endif
   }
 
-  remove_bom((char_u *)state->linebuf);
+  remove_bom(state->linebuf);
 
   return QF_OK;
 }
@@ -925,7 +925,7 @@ restofline:
   // match or no match.
   fields->valid = true;
   for (; fmt_ptr != NULL; fmt_ptr = fmt_ptr->next) {
-    idx = (char_u)fmt_ptr->prefix;
+    idx = (uint8_t)fmt_ptr->prefix;
     status = qf_parse_get_fields(linebuf, linelen, fmt_ptr, fields,
                                  qfl->qf_multiline, qfl->qf_multiscan,
                                  &tail);
@@ -5048,8 +5048,8 @@ void ex_cfile(exarg_T *eap)
   // first error.
   // :caddfile adds to an existing quickfix list. If there is no
   // quickfix list then a new list is created.
-  int res = qf_init(wp, (char *)p_ef, p_efm, (eap->cmdidx != CMD_caddfile
-                                              && eap->cmdidx != CMD_laddfile),
+  int res = qf_init(wp, p_ef, p_efm, (eap->cmdidx != CMD_caddfile
+                                      && eap->cmdidx != CMD_laddfile),
                     qf_cmdtitle(*eap->cmdlinep), enc);
   if (wp != NULL) {
     qi = GET_LOC_LIST(wp);
diff --git a/src/nvim/regexp.c b/src/nvim/regexp.c
index c2a7dd1011..122f3e2020 100644
--- a/src/nvim/regexp.c
+++ b/src/nvim/regexp.c
@@ -87,7 +87,7 @@ static int toggle_Magic(int x)
 #define REGMAGIC        0234
 
 // Utility definitions.
-#define UCHARAT(p)      ((int)(*(char_u *)(p)))
+#define UCHARAT(p)      ((int)(*(uint8_t *)(p)))
 
 // Used for an error (down from) vim_regcomp(): give the error message, set
 // rc_did_emsg and return NULL
@@ -327,7 +327,7 @@ static int reg_strict;          // "[abc" is illegal
 // uncrustify:off
 
 // META[] is used often enough to justify turning it into a table.
-static char_u META_flags[] = {
+static uint8_t META_flags[] = {
     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 //                 %  &     (  )  *  +        .
@@ -677,7 +677,7 @@ static int peekchr(void)
     // '$' is only magic as the very last char and if it's in front of
     // either "\|", "\)", "\&", or "\n"
     if (reg_magic >= MAGIC_OFF) {
-      char_u *p = (char_u *)regparse + 1;
+      uint8_t *p = (uint8_t *)regparse + 1;
       bool is_magic_all = (reg_magic == MAGIC_ALL);
 
       // ignore \c \C \m \M \v \V and \Z after '$'
@@ -938,7 +938,7 @@ static int read_limits(long *minval, long *maxval)
 // Sometimes need to save a copy of a line.  Since alloc()/free() is very
 // slow, we keep one allocated piece of memory and only re-allocate it when
 // it's too small.  It's freed in bt_regexec_both() when finished.
-static char_u *reg_tofree = NULL;
+static uint8_t *reg_tofree = NULL;
 static unsigned reg_tofreelen;
 
 // Structure used to store the execution state of the regex engine.
@@ -960,8 +960,8 @@ typedef struct {
   regmatch_T *reg_match;
   regmmatch_T *reg_mmatch;
 
-  char_u **reg_startp;
-  char_u **reg_endp;
+  uint8_t **reg_startp;
+  uint8_t **reg_endp;
   lpos_T *reg_startpos;
   lpos_T *reg_endpos;
 
@@ -973,8 +973,8 @@ typedef struct {
 
   // The current match-position is remembered with these variables:
   linenr_T lnum;  ///< line number, relative to first line
-  char_u *line;   ///< start of current line
-  char_u *input;  ///< current input, points into "line"
+  uint8_t *line;   ///< start of current line
+  uint8_t *input;  ///< current input, points into "line"
 
   int need_clear_subexpr;   ///< subexpressions still need to be cleared
   int need_clear_zsubexpr;  ///< extmatch subexpressions still need to be
@@ -1033,8 +1033,8 @@ static char *reg_getline(linenr_T lnum)
   return ml_get_buf(rex.reg_buf, rex.reg_firstlnum + lnum, false);
 }
 
-static char_u *reg_startzp[NSUBEXP];  // Workspace to mark beginning
-static char_u *reg_endzp[NSUBEXP];    //   and end of \z(...\) matches
+static uint8_t *reg_startzp[NSUBEXP];  // Workspace to mark beginning
+static uint8_t *reg_endzp[NSUBEXP];    //   and end of \z(...\) matches
 static lpos_T reg_startzpos[NSUBEXP];   // idem, beginning pos
 static lpos_T reg_endzpos[NSUBEXP];     // idem, end pos
 
@@ -1147,7 +1147,7 @@ static bool reg_match_visual(void)
     }
 
     // getvvcol() flushes rex.line, need to get it again
-    rex.line = (char_u *)reg_getline(rex.lnum);
+    rex.line = (uint8_t *)reg_getline(rex.lnum);
     rex.input = rex.line + col;
 
     unsigned int cols_u = win_linetabsize(wp, rex.reg_firstlnum + rex.lnum, (char *)rex.line, col);
@@ -1219,7 +1219,7 @@ static void cleanup_zsubexpr(void)
 // Advance rex.lnum, rex.line and rex.input to the next line.
 static void reg_nextline(void)
 {
-  rex.line = (char_u *)reg_getline(++rex.lnum);
+  rex.line = (uint8_t *)reg_getline(++rex.lnum);
   rex.input = rex.line;
   fast_breakcheck();
 }
@@ -2293,7 +2293,7 @@ static regengine_T nfa_regengine = {
 static int regexp_engine = 0;
 
 #ifdef REGEXP_DEBUG
-static char_u regname[][30] = {
+static uint8_t regname[][30] = {
   "AUTOMATIC Regexp Engine",
   "BACKTRACKING Regexp Engine",
   "NFA Regexp Engine"
@@ -2342,10 +2342,10 @@ regprog_T *vim_regcomp(char *expr_arg, int re_flags)
   //
   const int called_emsg_before = called_emsg;
   if (regexp_engine != BACKTRACKING_ENGINE) {
-    prog = nfa_regengine.regcomp((char_u *)expr,
+    prog = nfa_regengine.regcomp((uint8_t *)expr,
                                  re_flags + (regexp_engine == AUTOMATIC_ENGINE ? RE_AUTO : 0));
   } else {
-    prog = bt_regengine.regcomp((char_u *)expr, re_flags);
+    prog = bt_regengine.regcomp((uint8_t *)expr, re_flags);
   }
 
   // Check for error compiling regexp with initial engine.
@@ -2370,7 +2370,7 @@ regprog_T *vim_regcomp(char *expr_arg, int re_flags)
     if (regexp_engine == AUTOMATIC_ENGINE && called_emsg == called_emsg_before) {
       regexp_engine = BACKTRACKING_ENGINE;
       report_re_switch(expr);
-      prog = bt_regengine.regcomp((char_u *)expr, re_flags);
+      prog = bt_regengine.regcomp((uint8_t *)expr, re_flags);
     }
   }
 
@@ -2448,7 +2448,7 @@ static bool vim_regexec_string(regmatch_T *rmp, char *line, colnr_T col, bool nl
   rex.reg_startpos = NULL;
   rex.reg_endpos = NULL;
 
-  int result = rmp->regprog->engine->regexec_nl(rmp, (char_u *)line, col, nl);
+  int result = rmp->regprog->engine->regexec_nl(rmp, (uint8_t *)line, col, nl);
   rmp->regprog->re_in_use = false;
 
   // NFA engine aborted because it's very slow, use backtracking engine instead.
@@ -2464,7 +2464,7 @@ static bool vim_regexec_string(regmatch_T *rmp, char *line, colnr_T col, bool nl
     rmp->regprog = vim_regcomp(pat, re_flags);
     if (rmp->regprog != NULL) {
       rmp->regprog->re_in_use = true;
-      result = rmp->regprog->engine->regexec_nl(rmp, (char_u *)line, col, nl);
+      result = rmp->regprog->engine->regexec_nl(rmp, (uint8_t *)line, col, nl);
       rmp->regprog->re_in_use = false;
     }
 
diff --git a/src/nvim/regexp_bt.c b/src/nvim/regexp_bt.c
index d8471a7b12..1b32447d77 100644
--- a/src/nvim/regexp_bt.c
+++ b/src/nvim/regexp_bt.c
@@ -242,17 +242,17 @@
 
 static int prevchr_len;         ///< byte length of previous char
 static int num_complex_braces;  ///< Complex \{...} count
-static char_u *regcode;         ///< Code-emit pointer, or JUST_CALC_SIZE
+static uint8_t *regcode;         ///< Code-emit pointer, or JUST_CALC_SIZE
 static long regsize;            ///< Code size.
 static int reg_toolong;         ///< true when offset out of range
-static char_u had_endbrace[NSUBEXP];  ///< flags, true if end of () found
+static uint8_t had_endbrace[NSUBEXP];  ///< flags, true if end of () found
 static long brace_min[10];        ///< Minimums for complex brace repeats
 static long brace_max[10];        ///< Maximums for complex brace repeats
 static int brace_count[10];       ///< Current counts for complex brace repeats
 static int one_exactly = false;   ///< only do one char for EXACTLY
 
 // When making changes to classchars also change nfa_classcodes.
-static char_u *classchars = (char_u *)".iIkKfFpPsSdDxXoOwWhHaAlLuU";
+static uint8_t *classchars = (uint8_t *)".iIkKfFpPsSdDxXoOwWhHaAlLuU";
 static int classcodes[] = {
   ANY, IDENT, SIDENT, KWORD, SKWORD,
   FNAME, SFNAME, PRINT, SPRINT,
@@ -265,7 +265,7 @@ static int classcodes[] = {
 
 // When regcode is set to this value, code is not emitted and size is computed
 // instead.
-#define JUST_CALC_SIZE  ((char_u *)-1)
+#define JUST_CALC_SIZE  ((uint8_t *)-1)
 
 // Values for rs_state in regitem_T.
 typedef enum regstate_E {
@@ -290,7 +290,7 @@ typedef enum regstate_E {
 // Also stores the length of "backpos".
 typedef struct {
   union {
-    char_u *ptr;       // rex.input pointer, for single-line regexp
+    uint8_t *ptr;       // rex.input pointer, for single-line regexp
     lpos_T pos;        // rex.input pos, for multi-line regexp
   } rs_u;
   int rs_len;
@@ -299,7 +299,7 @@ typedef struct {
 // struct to save start/end pointer/position in for \(\)
 typedef struct {
   union {
-    char_u *ptr;
+    uint8_t *ptr;
     lpos_T pos;
   } se_u;
 } save_se_T;
@@ -320,7 +320,7 @@ typedef struct regbehind_S {
 typedef struct regitem_S {
   regstate_T rs_state;         // what we are doing, one of RS_ above
   int16_t rs_no;            // submatch nr or BEHIND/NOBEHIND
-  char_u *rs_scan;         // current node in program
+  uint8_t *rs_scan;         // current node in program
   union {
     save_se_T sesave;
     regsave_T regsave;
@@ -339,7 +339,7 @@ typedef struct regstar_S {
 // used to store input position when a BACK was encountered, so that we now if
 // we made any progress since the last time.
 typedef struct backpos_S {
-  char_u *bp_scan;         // "scan" where BACK was encountered
+  uint8_t *bp_scan;         // "scan" where BACK was encountered
   regsave_T bp_pos;           // last input position
 } backpos_T;
 
@@ -411,14 +411,14 @@ static regsave_T behind_pos;
 // Obtain a second single-byte operand stored after a four bytes operand.
 #define OPERAND_CMP(p)  (p)[7]
 
-static char_u *reg(int paren, int *flagp);
+static uint8_t *reg(int paren, int *flagp);
 
 #ifdef BT_REGEXP_DUMP
-static void     regdump(char_u *, bt_regprog_T *);
+static void     regdump(uint8_t *, bt_regprog_T *);
 #endif
 
 #ifdef REGEXP_DEBUG
-static char_u *regprop(char_u *);
+static uint8_t *regprop(uint8_t *);
 
 static int regnarrate = 0;
 #endif
@@ -428,7 +428,7 @@ static int regnarrate = 0;
 #endif
 
 // Setup to parse the regexp.  Used once to get the length and once to do it.
-static void regcomp_start(char_u *expr, int re_flags)                        // see vim_regcomp()
+static void regcomp_start(uint8_t *expr, int re_flags)                        // see vim_regcomp()
 {
   initchr((char *)expr);
   if (re_flags & RE_MAGIC) {
@@ -466,7 +466,7 @@ static void regc(int b)
   if (regcode == JUST_CALC_SIZE) {
     regsize++;
   } else {
-    *regcode++ = (char_u)b;
+    *regcode++ = (uint8_t)b;
   }
 }
 
@@ -1453,15 +1453,15 @@ static void reg_equi_class(int c)
 
 // Emit a node.
 // Return pointer to generated code.
-static char_u *regnode(int op)
+static uint8_t *regnode(int op)
 {
-  char_u *ret;
+  uint8_t *ret;
 
   ret = regcode;
   if (ret == JUST_CALC_SIZE) {
     regsize += 3;
   } else {
-    *regcode++ = (char_u)op;
+    *regcode++ = (uint8_t)op;
     *regcode++ = NUL;                   // Null "next" pointer.
     *regcode++ = NUL;
   }
@@ -1469,19 +1469,19 @@ static char_u *regnode(int op)
 }
 
 // Write a four bytes number at "p" and return pointer to the next char.
-static char_u *re_put_uint32(char_u *p, uint32_t val)
+static uint8_t *re_put_uint32(uint8_t *p, uint32_t val)
 {
-  *p++ = (char_u)((val >> 24) & 0377);
-  *p++ = (char_u)((val >> 16) & 0377);
-  *p++ = (char_u)((val >> 8) & 0377);
-  *p++ = (char_u)(val & 0377);
+  *p++ = (uint8_t)((val >> 24) & 0377);
+  *p++ = (uint8_t)((val >> 16) & 0377);
+  *p++ = (uint8_t)((val >> 8) & 0377);
+  *p++ = (uint8_t)(val & 0377);
   return p;
 }
 
 // regnext - dig the "next" pointer out of a node
 // Returns NULL when calculating size, when there is no next item and when
 // there is an error.
-static char_u *regnext(char_u *p)
+static uint8_t *regnext(uint8_t *p)
   FUNC_ATTR_NONNULL_ALL
 {
   int offset;
@@ -1503,7 +1503,7 @@ static char_u *regnext(char_u *p)
 }
 
 // Set the next-pointer at the end of a node chain.
-static void regtail(char_u *p, char_u *val)
+static void regtail(uint8_t *p, uint8_t *val)
 {
   int offset;
 
@@ -1512,9 +1512,9 @@ static void regtail(char_u *p, char_u *val)
   }
 
   // Find last node.
-  char_u *scan = p;
+  uint8_t *scan = p;
   for (;;) {
-    char_u *temp = regnext(scan);
+    uint8_t *temp = regnext(scan);
     if (temp == NULL) {
       break;
     }
@@ -1532,13 +1532,13 @@ static void regtail(char_u *p, char_u *val)
   if (offset > 0xffff) {
     reg_toolong = true;
   } else {
-    *(scan + 1) = (char_u)(((unsigned)offset >> 8) & 0377);
-    *(scan + 2) = (char_u)(offset & 0377);
+    *(scan + 1) = (uint8_t)(((unsigned)offset >> 8) & 0377);
+    *(scan + 2) = (uint8_t)(offset & 0377);
   }
 }
 
 // Like regtail, on item after a BRANCH; nop if none.
-static void regoptail(char_u *p, char_u *val)
+static void regoptail(uint8_t *p, uint8_t *val)
 {
   // When op is neither BRANCH nor BRACE_COMPLEX0-9, it is "operandless"
   if (p == NULL || p == JUST_CALC_SIZE
@@ -1552,11 +1552,11 @@ static void regoptail(char_u *p, char_u *val)
 // Insert an operator in front of already-emitted operand
 //
 // Means relocating the operand.
-static void reginsert(int op, char_u *opnd)
+static void reginsert(int op, uint8_t *opnd)
 {
-  char_u *src;
-  char_u *dst;
-  char_u *place;
+  uint8_t *src;
+  uint8_t *dst;
+  uint8_t *place;
 
   if (regcode == JUST_CALC_SIZE) {
     regsize += 3;
@@ -1570,18 +1570,18 @@ static void reginsert(int op, char_u *opnd)
   }
 
   place = opnd;                 // Op node, where operand used to be.
-  *place++ = (char_u)op;
+  *place++ = (uint8_t)op;
   *place++ = NUL;
   *place = NUL;
 }
 
 // Insert an operator in front of already-emitted operand.
 // Add a number to the operator.
-static void reginsert_nr(int op, long val, char_u *opnd)
+static void reginsert_nr(int op, long val, uint8_t *opnd)
 {
-  char_u *src;
-  char_u *dst;
-  char_u *place;
+  uint8_t *src;
+  uint8_t *dst;
+  uint8_t *place;
 
   if (regcode == JUST_CALC_SIZE) {
     regsize += 7;
@@ -1595,7 +1595,7 @@ static void reginsert_nr(int op, long val, char_u *opnd)
   }
 
   place = opnd;                 // Op node, where operand used to be.
-  *place++ = (char_u)op;
+  *place++ = (uint8_t)op;
   *place++ = NUL;
   *place++ = NUL;
   assert(val >= 0 && (uintmax_t)val <= UINT32_MAX);
@@ -1606,11 +1606,11 @@ static void reginsert_nr(int op, long val, char_u *opnd)
 // The operator has the given limit values as operands.  Also set next pointer.
 //
 // Means relocating the operand.
-static void reginsert_limits(int op, long minval, long maxval, char_u *opnd)
+static void reginsert_limits(int op, long minval, long maxval, uint8_t *opnd)
 {
-  char_u *src;
-  char_u *dst;
-  char_u *place;
+  uint8_t *src;
+  uint8_t *dst;
+  uint8_t *place;
 
   if (regcode == JUST_CALC_SIZE) {
     regsize += 11;
@@ -1624,7 +1624,7 @@ static void reginsert_limits(int op, long minval, long maxval, char_u *opnd)
   }
 
   place = opnd;                 // Op node, where operand used to be.
-  *place++ = (char_u)op;
+  *place++ = (uint8_t)op;
   *place++ = NUL;
   *place++ = NUL;
   assert(minval >= 0 && (uintmax_t)minval <= UINT32_MAX);
@@ -1641,11 +1641,11 @@ static void reginsert_limits(int op, long minval, long maxval, char_u *opnd)
 static int seen_endbrace(int refnum)
 {
   if (!had_endbrace[refnum]) {
-    char_u *p;
+    uint8_t *p;
 
     // Trick: check if "@<=" or "@<!" follows, in which case
     // the \1 can appear before the referenced match.
-    for (p = (char_u *)regparse; *p != NUL; p++) {
+    for (p = (uint8_t *)regparse; *p != NUL; p++) {
       if (p[0] == '@' && p[1] == '<' && (p[2] == '!' || p[2] == '=')) {
         break;
       }
@@ -1665,12 +1665,12 @@ static int seen_endbrace(int refnum)
 // Optimization:  gobbles an entire sequence of ordinary characters so that
 // it can turn them into a single node, which is smaller to store and
 // faster to run.  Don't do this when one_exactly is set.
-static char_u *regatom(int *flagp)
+static uint8_t *regatom(int *flagp)
 {
-  char_u *ret;
+  uint8_t *ret;
   int flags;
   int c;
-  char_u *p;
+  uint8_t *p;
   int extra = 0;
   int save_prev_at_start = prev_at_start;
 
@@ -1746,7 +1746,7 @@ static char_u *regatom(int *flagp)
   case Magic('L'):
   case Magic('u'):
   case Magic('U'):
-    p = (char_u *)vim_strchr((char *)classchars, no_Magic(c));
+    p = (uint8_t *)vim_strchr((char *)classchars, no_Magic(c));
     if (p == NULL) {
       EMSG_RET_NULL(_("E63: invalid use of \\_"));
     }
@@ -1808,17 +1808,17 @@ static char_u *regatom(int *flagp)
 
   case Magic('~'):              // previous substitute pattern
     if (reg_prev_sub != NULL) {
-      char_u *lp;
+      uint8_t *lp;
 
       ret = regnode(EXACTLY);
-      lp = (char_u *)reg_prev_sub;
+      lp = (uint8_t *)reg_prev_sub;
       while (*lp != NUL) {
         regc(*lp++);
       }
       regc(NUL);
       if (*reg_prev_sub != NUL) {
         *flagp |= HASWIDTH;
-        if ((lp - (char_u *)reg_prev_sub) == 1) {
+        if ((lp - (uint8_t *)reg_prev_sub) == 1) {
           *flagp |= SIMPLE;
         }
       }
@@ -1948,9 +1948,9 @@ static char_u *regatom(int *flagp)
         EMSG_ONE_RET_NULL;
       }
       {
-        char_u *lastbranch;
-        char_u *lastnode = NULL;
-        char_u *br;
+        uint8_t *lastbranch;
+        uint8_t *lastnode = NULL;
+        uint8_t *br;
 
         ret = NULL;
         while ((c = getchr()) != ']') {
@@ -2072,8 +2072,8 @@ static char_u *regatom(int *flagp)
           if (ret == JUST_CALC_SIZE) {
             regsize += 2;
           } else {
-            *regcode++ = (char_u)c;
-            *regcode++ = (char_u)cmp;
+            *regcode++ = (uint8_t)c;
+            *regcode++ = (uint8_t)cmp;
           }
           break;
         } else if ((c == 'l' || c == 'c' || c == 'v') && (cur || got_digit)) {
@@ -2110,7 +2110,7 @@ static char_u *regatom(int *flagp)
             // put the number and the optional
             // comparator after the opcode
             regcode = re_put_uint32(regcode, n);
-            *regcode++ = (char_u)cmp;
+            *regcode++ = (uint8_t)cmp;
           }
           break;
         }
@@ -2124,11 +2124,11 @@ static char_u *regatom(int *flagp)
   case Magic('['):
 collection:
     {
-      char_u *lp;
+      uint8_t *lp;
 
       // If there is no matching ']', we assume the '[' is a normal
       // character.  This makes 'incsearch' and ":help [" work.
-      lp = (char_u *)skip_anyof(regparse);
+      lp = (uint8_t *)skip_anyof(regparse);
       if (*lp == ']') {         // there is a matching ']'
         int startc = -1;                // > 0 when next '-' is a range
         int endc;
@@ -2460,11 +2460,11 @@ do_multibyte:
 // both the endmarker for their branch list and the body of the last branch.
 // It might seem that this node could be dispensed with entirely, but the
 // endmarker role is not redundant.
-static char_u *regpiece(int *flagp)
+static uint8_t *regpiece(int *flagp)
 {
-  char_u *ret;
+  uint8_t *ret;
   int op;
-  char_u *next;
+  uint8_t *next;
   int flags;
   long minval;
   long maxval;
@@ -2597,11 +2597,11 @@ static char_u *regpiece(int *flagp)
 
 // Parse one alternative of an | or & operator.
 // Implements the concatenation operator.
-static char_u *regconcat(int *flagp)
+static uint8_t *regconcat(int *flagp)
 {
-  char_u *first = NULL;
-  char_u *chain = NULL;
-  char_u *latest;
+  uint8_t *first = NULL;
+  uint8_t *chain = NULL;
+  uint8_t *latest;
   int flags;
   int cont = true;
 
@@ -2673,11 +2673,11 @@ static char_u *regconcat(int *flagp)
 
 // Parse one alternative of an | operator.
 // Implements the & operator.
-static char_u *regbranch(int *flagp)
+static uint8_t *regbranch(int *flagp)
 {
-  char_u *ret;
-  char_u *chain = NULL;
-  char_u *latest;
+  uint8_t *ret;
+  uint8_t *chain = NULL;
+  uint8_t *latest;
   int flags;
 
   *flagp = WORST | HASNL;               // Tentatively.
@@ -2722,11 +2722,11 @@ static char_u *regbranch(int *flagp)
 /// follows makes it hard to avoid.
 ///
 /// @param paren  REG_NOPAREN, REG_PAREN, REG_NPAREN or REG_ZPAREN
-static char_u *reg(int paren, int *flagp)
+static uint8_t *reg(int paren, int *flagp)
 {
-  char_u *ret;
-  char_u *br;
-  char_u *ender;
+  uint8_t *ret;
+  uint8_t *br;
+  uint8_t *ender;
   int parno = 0;
   int flags;
 
@@ -2840,10 +2840,10 @@ static char_u *reg(int paren, int *flagp)
 // Beware that the optimization-preparation code in here knows about some
 // of the structure of the compiled regexp.
 // "re_flags": RE_MAGIC and/or RE_STRING.
-static regprog_T *bt_regcomp(char_u *expr, int re_flags)
+static regprog_T *bt_regcomp(uint8_t *expr, int re_flags)
 {
-  char_u *scan;
-  char_u *longest;
+  uint8_t *scan;
+  uint8_t *longest;
   int len;
   int flags;
 
@@ -2890,7 +2890,7 @@ static regprog_T *bt_regcomp(char_u *expr, int re_flags)
     r->regflags |= RF_LOOKBH;
   }
   // Remember whether this pattern has any \z specials in it.
-  r->reghasz = (char_u)re_has_z;
+  r->reghasz = (uint8_t)re_has_z;
   scan = r->program + 1;        // First BRANCH.
   if (OP(regnext(scan)) == END) {   // Only one top-level choice.
     scan = OPERAND(scan);
@@ -2908,7 +2908,7 @@ static regprog_T *bt_regcomp(char_u *expr, int re_flags)
                || OP(scan) == NOTHING
                || OP(scan) == MOPEN + 0 || OP(scan) == NOPEN
                || OP(scan) == MCLOSE + 0 || OP(scan) == NCLOSE) {
-      char_u *regnext_scan = regnext(scan);
+      uint8_t *regnext_scan = regnext(scan);
       if (OP(regnext_scan) == EXACTLY) {
         r->regstart = utf_ptr2char((char *)OPERAND(regnext_scan));
       }
@@ -3014,7 +3014,7 @@ static void reg_restore(regsave_T *save, garray_T *gap)
       // only call reg_getline() when the line number changed to save
       // a bit of time
       rex.lnum = save->rs_u.pos.lnum;
-      rex.line = (char_u *)reg_getline(rex.lnum);
+      rex.line = (uint8_t *)reg_getline(rex.lnum);
     }
     rex.input = rex.line + save->rs_u.pos.col;
   } else {
@@ -3057,7 +3057,7 @@ static void save_se_multi(save_se_T *savep, lpos_T *posp)
   posp->col = (colnr_T)(rex.input - rex.line);
 }
 
-static void save_se_one(save_se_T *savep, char_u **pp)
+static void save_se_one(save_se_T *savep, uint8_t **pp)
 {
   savep->se_u.ptr = *pp;
   *pp = rex.input;
@@ -3067,14 +3067,14 @@ static void save_se_one(save_se_T *savep, char_u **pp)
 /// Advances rex.input (and rex.lnum) to just after the matched chars.
 ///
 /// @param maxcount  maximum number of matches allowed
-static int regrepeat(char_u *p, long maxcount)
+static int regrepeat(uint8_t *p, long maxcount)
 {
   long count = 0;
-  char_u *opnd;
+  uint8_t *opnd;
   int mask;
   int testval = 0;
 
-  char_u *scan = rex.input;  // Make local copy of rex.input for speed.
+  uint8_t *scan = rex.input;  // Make local copy of rex.input for speed.
   opnd = OPERAND(p);
   switch (OP(p)) {
   case ANY:
@@ -3431,7 +3431,7 @@ do_class:
 
 // Push an item onto the regstack.
 // Returns pointer to new item.  Returns NULL when out of memory.
-static regitem_T *regstack_push(regstate_T state, char_u *scan)
+static regitem_T *regstack_push(regstate_T state, uint8_t *scan)
 {
   regitem_T *rp;
 
@@ -3450,7 +3450,7 @@ static regitem_T *regstack_push(regstate_T state, char_u *scan)
 }
 
 // Pop an item from the regstack.
-static void regstack_pop(char_u **scan)
+static void regstack_pop(uint8_t **scan)
 {
   regitem_T *rp;
 
@@ -3520,9 +3520,9 @@ static void restore_subexpr(regbehind_T *bp)
 ///         just after the last matched character.
 ///         - false when there is no match.  Leaves rex.input and rex.lnum in an
 ///         undefined state!
-static bool regmatch(char_u *scan, proftime_T *tm, int *timed_out)
+static bool regmatch(uint8_t *scan, proftime_T *tm, int *timed_out)
 {
-  char_u *next;          // Next node.
+  uint8_t *next;          // Next node.
   int op;
   int c;
   regitem_T *rp;
@@ -3651,7 +3651,7 @@ static bool regmatch(char_u *scan, proftime_T *tm, int *timed_out)
 
           // Line may have been freed, get it again.
           if (REG_MULTI) {
-            rex.line = (char_u *)reg_getline(rex.lnum);
+            rex.line = (uint8_t *)reg_getline(rex.lnum);
             rex.input = rex.line + col;
           }
 
@@ -3965,7 +3965,7 @@ static bool regmatch(char_u *scan, proftime_T *tm, int *timed_out)
 
         case EXACTLY: {
           int len;
-          char_u *opnd;
+          uint8_t *opnd;
 
           opnd = OPERAND(scan);
           // Inline the first byte, for speed.
@@ -4017,7 +4017,7 @@ static bool regmatch(char_u *scan, proftime_T *tm, int *timed_out)
         case MULTIBYTECODE: {
           int i, len;
 
-          const char_u *opnd = OPERAND(scan);
+          const uint8_t *opnd = OPERAND(scan);
           // Safety check (just in case 'encoding' was changed since
           // compiling the program).
           if ((len = utfc_ptr2len((char *)opnd)) < 2) {
@@ -4703,8 +4703,8 @@ static bool regmatch(char_u *scan, proftime_T *tm, int *timed_out)
                   (colnr_T)strlen((char *)rex.line);
               }
             } else {
-              const char_u *const line =
-                (char_u *)reg_getline(rp->rs_un.regsave.rs_u.pos.lnum);
+              const uint8_t *const line =
+                (uint8_t *)reg_getline(rp->rs_un.regsave.rs_u.pos.lnum);
 
               rp->rs_un.regsave.rs_u.pos.col -=
                 utf_head_off((char *)line,
@@ -4786,7 +4786,7 @@ static bool regmatch(char_u *scan, proftime_T *tm, int *timed_out)
                   break;
                 }
                 rex.lnum--;
-                rex.line = (char_u *)reg_getline(rex.lnum);
+                rex.line = (uint8_t *)reg_getline(rex.lnum);
                 // Just in case regrepeat() didn't count right.
                 if (rex.line == NULL) {
                   break;
@@ -4917,13 +4917,13 @@ static long regtry(bt_regprog_T *prog, colnr_T col, proftime_T *tm, int *timed_o
             && reg_endzpos[i].lnum == reg_startzpos[i].lnum
             && reg_endzpos[i].col >= reg_startzpos[i].col) {
           re_extmatch_out->matches[i] =
-            (char_u *)xstrnsave((char *)reg_getline(reg_startzpos[i].lnum) + reg_startzpos[i].col,
-                                (size_t)(reg_endzpos[i].col - reg_startzpos[i].col));
+            (uint8_t *)xstrnsave((char *)reg_getline(reg_startzpos[i].lnum) + reg_startzpos[i].col,
+                                 (size_t)(reg_endzpos[i].col - reg_startzpos[i].col));
         }
       } else {
         if (reg_startzp[i] != NULL && reg_endzp[i] != NULL) {
           re_extmatch_out->matches[i] =
-            (char_u *)xstrnsave((char *)reg_startzp[i], (size_t)(reg_endzp[i] - reg_startzp[i]));
+            (uint8_t *)xstrnsave((char *)reg_startzp[i], (size_t)(reg_endzp[i] - reg_startzp[i]));
         }
       }
     }
@@ -4939,10 +4939,10 @@ static long regtry(bt_regprog_T *prog, colnr_T col, proftime_T *tm, int *timed_o
 /// @param timed_out  flag set on timeout or NULL
 ///
 /// @return  0 for failure, or number of lines contained in the match.
-static long bt_regexec_both(char_u *line, colnr_T startcol, proftime_T *tm, int *timed_out)
+static long bt_regexec_both(uint8_t *line, colnr_T startcol, proftime_T *tm, int *timed_out)
 {
   bt_regprog_T *prog;
-  char_u *s;
+  uint8_t *s;
   colnr_T col = startcol;
   long retval = 0L;
 
@@ -4966,13 +4966,13 @@ static long bt_regexec_both(char_u *line, colnr_T startcol, proftime_T *tm, int
 
   if (REG_MULTI) {
     prog = (bt_regprog_T *)rex.reg_mmatch->regprog;
-    line = (char_u *)reg_getline((linenr_T)0);
+    line = (uint8_t *)reg_getline((linenr_T)0);
     rex.reg_startpos = rex.reg_mmatch->startpos;
     rex.reg_endpos = rex.reg_mmatch->endpos;
   } else {
     prog = (bt_regprog_T *)rex.reg_match->regprog;
-    rex.reg_startp = (char_u **)rex.reg_match->startp;
-    rex.reg_endp = (char_u **)rex.reg_match->endp;
+    rex.reg_startp = (uint8_t **)rex.reg_match->startp;
+    rex.reg_endp = (uint8_t **)rex.reg_match->endp;
   }
 
   // Be paranoid...
@@ -5011,14 +5011,14 @@ static long bt_regexec_both(char_u *line, colnr_T startcol, proftime_T *tm, int
     // This is used very often, esp. for ":global".  Use two versions of
     // the loop to avoid overhead of conditions.
     if (!rex.reg_ic) {
-      while ((s = (char_u *)vim_strchr((char *)s, c)) != NULL) {
+      while ((s = (uint8_t *)vim_strchr((char *)s, c)) != NULL) {
         if (cstrncmp((char *)s, (char *)prog->regmust, &prog->regmlen) == 0) {
           break;  // Found it.
         }
         MB_PTR_ADV(s);
       }
     } else {
-      while ((s = (char_u *)cstrchr((char *)s, c)) != NULL) {
+      while ((s = (uint8_t *)cstrchr((char *)s, c)) != NULL) {
         if (cstrncmp((char *)s, (char *)prog->regmust, &prog->regmlen) == 0) {
           break;  // Found it.
         }
@@ -5053,7 +5053,7 @@ static long bt_regexec_both(char_u *line, colnr_T startcol, proftime_T *tm, int
     while (!got_int) {
       if (prog->regstart != NUL) {
         // Skip until the char we know it must start with.
-        s = (char_u *)cstrchr((char *)rex.line + col, prog->regstart);
+        s = (uint8_t *)cstrchr((char *)rex.line + col, prog->regstart);
         if (s == NULL) {
           retval = 0;
           break;
@@ -5075,7 +5075,7 @@ static long bt_regexec_both(char_u *line, colnr_T startcol, proftime_T *tm, int
       // if not currently on the first line, get it again
       if (rex.lnum != 0) {
         rex.lnum = 0;
-        rex.line = (char_u *)reg_getline((linenr_T)0);
+        rex.line = (uint8_t *)reg_getline((linenr_T)0);
       }
       if (rex.line[col] == NUL) {
         break;
@@ -5145,7 +5145,7 @@ theend:
 /// @param col   column to start looking for match
 ///
 /// @return  0 for failure, number of lines contained in the match otherwise.
-static int bt_regexec_nl(regmatch_T *rmp, char_u *line, colnr_T col, bool line_lbr)
+static int bt_regexec_nl(regmatch_T *rmp, uint8_t *line, colnr_T col, bool line_lbr)
 {
   rex.reg_match = rmp;
   rex.reg_mmatch = NULL;
@@ -5182,7 +5182,7 @@ static long bt_regexec_multi(regmmatch_T *rmp, win_T *win, buf_T *buf, linenr_T
 }
 
 // Compare a number with the operand of RE_LNUM, RE_COL or RE_VCOL.
-static int re_num_cmp(uint32_t val, char_u *scan)
+static int re_num_cmp(uint32_t val, uint8_t *scan)
 {
   uint32_t n = (uint32_t)OPERAND_MIN(scan);
 
@@ -5198,12 +5198,12 @@ static int re_num_cmp(uint32_t val, char_u *scan)
 #ifdef BT_REGEXP_DUMP
 
 // regdump - dump a regexp onto stdout in vaguely comprehensible form
-static void regdump(char_u *pattern, bt_regprog_T *r)
+static void regdump(uint8_t *pattern, bt_regprog_T *r)
 {
-  char_u *s;
+  uint8_t *s;
   int op = EXACTLY;             // Arbitrary non-END op.
-  char_u *next;
-  char_u *end = NULL;
+  uint8_t *next;
+  uint8_t *end = NULL;
   FILE *f;
 
 # ifdef BT_REGEXP_LOG
@@ -5284,7 +5284,7 @@ static void regdump(char_u *pattern, bt_regprog_T *r)
 #ifdef REGEXP_DEBUG
 
 // regprop - printable representation of opcode
-static char_u *regprop(char_u *op)
+static uint8_t *regprop(uint8_t *op)
 {
   char *p;
   static char buf[50];
@@ -5656,6 +5656,6 @@ static char_u *regprop(char_u *op)
   if (p != NULL) {
     STRCAT(buf, p);
   }
-  return (char_u *)buf;
+  return (uint8_t *)buf;
 }
 #endif      // REGEXP_DEBUG
diff --git a/src/nvim/regexp_nfa.c b/src/nvim/regexp_nfa.c
index 83a74b6091..93b03f0632 100644
--- a/src/nvim/regexp_nfa.c
+++ b/src/nvim/regexp_nfa.c
@@ -244,10 +244,10 @@ static int nfa_classcodes[] = {
   NFA_UPPER, NFA_NUPPER
 };
 
-static char_u e_nul_found[] = N_("E865: (NFA) Regexp end encountered prematurely");
-static char_u e_misplaced[] = N_("E866: (NFA regexp) Misplaced %c");
-static char_u e_ill_char_class[] = N_("E877: (NFA regexp) Invalid character class: %" PRId64);
-static char_u e_value_too_large[] = N_("E951: \\% value too large");
+static char e_nul_found[] = N_("E865: (NFA) Regexp end encountered prematurely");
+static char e_misplaced[] = N_("E866: (NFA regexp) Misplaced %c");
+static char e_ill_char_class[] = N_("E877: (NFA regexp) Invalid character class: %" PRId64);
+static char e_value_too_large[] = N_("E951: \\% value too large");
 
 // Since the out pointers in the list are always
 // uninitialized, we use the pointers themselves
@@ -276,8 +276,8 @@ typedef struct {
       colnr_T end_col;
     } multi[NSUBEXP];
     struct linepos {
-      char_u *start;
-      char_u *end;
+      uint8_t *start;
+      uint8_t *end;
     } line[NSUBEXP];
   } list;
   colnr_T orig_start_col;  // list.multi[0].start_col without \zs
@@ -296,7 +296,7 @@ struct nfa_pim_S {
   regsubs_T subs;               // submatch info, only party used
   union {
     lpos_T pos;
-    char_u *ptr;
+    uint8_t *ptr;
   } end;                        // where the match must end
 };
 
@@ -354,7 +354,7 @@ static int nfa_ll_index = 0;
 /// Initialize internal variables before NFA compilation.
 ///
 /// @param re_flags  @see vim_regcomp()
-static void nfa_regcomp_start(char_u *expr, int re_flags)
+static void nfa_regcomp_start(uint8_t *expr, int re_flags)
 {
   size_t postfix_size;
   size_t nstate_max;
@@ -519,12 +519,12 @@ static int nfa_get_regstart(nfa_state_T *start, int depth)
 // Figure out if the NFA state list contains just literal text and nothing
 // else.  If so return a string in allocated memory with what must match after
 // regstart.  Otherwise return NULL.
-static char_u *nfa_get_match_text(nfa_state_T *start)
+static uint8_t *nfa_get_match_text(nfa_state_T *start)
 {
   nfa_state_T *p = start;
   int len = 0;
-  char_u *ret;
-  char_u *s;
+  uint8_t *ret;
+  uint8_t *s;
 
   if (p->c != NFA_MOPEN) {
     return NULL;     // just in case
@@ -571,7 +571,7 @@ static void realloc_post_list(void)
 // to the closing brace.
 // Keep in mind that 'ignorecase' applies at execution time, thus [a-z] may
 // need to be interpreted as [a-zA-Z].
-static int nfa_recognize_char_class(char_u *start, char_u *end, int extra_newl)
+static int nfa_recognize_char_class(uint8_t *start, uint8_t *end, int extra_newl)
 {
 #define CLASS_not            0x80
 #define CLASS_af             0x40
@@ -582,7 +582,7 @@ static int nfa_recognize_char_class(char_u *start, char_u *end, int extra_newl)
 #define CLASS_o9             0x02
 #define CLASS_underscore     0x01
 
-  char_u *p;
+  uint8_t *p;
   int config = 0;
 
   bool newl = extra_newl == true;
@@ -1788,9 +1788,9 @@ static int nfa_regatom(void)
   int equiclass;
   int collclass;
   int got_coll_char;
-  char_u *p;
-  char_u *endp;
-  char_u *old_regparse = (char_u *)regparse;
+  uint8_t *p;
+  uint8_t *endp;
+  uint8_t *old_regparse = (uint8_t *)regparse;
   int extra = 0;
   int emit_range;
   int negated;
@@ -1873,7 +1873,7 @@ static int nfa_regatom(void)
   case Magic('L'):
   case Magic('u'):
   case Magic('U'):
-    p = (char_u *)vim_strchr((char *)classchars, no_Magic(c));
+    p = (uint8_t *)vim_strchr((char *)classchars, no_Magic(c));
     if (p == NULL) {
       if (extra == NFA_ADD_NL) {
         semsg(_(e_ill_char_class), (int64_t)c);
@@ -1886,7 +1886,7 @@ static int nfa_regatom(void)
     // When '.' is followed by a composing char ignore the dot, so that
     // the composing char is matched here.
     if (c == Magic('.') && utf_iscomposing(peekchr())) {
-      old_regparse = (char_u *)regparse;
+      old_regparse = (uint8_t *)regparse;
       c = getchr();
       goto nfa_do_multibyte;
     }
@@ -1932,7 +1932,7 @@ static int nfa_regatom(void)
     return FAIL;
 
   case Magic('~'): {
-    char_u *lp;
+    uint8_t *lp;
 
     // Previous substitute pattern.
     // Generated as "\%(pattern\)".
@@ -1940,9 +1940,9 @@ static int nfa_regatom(void)
       emsg(_(e_nopresub));
       return FAIL;
     }
-    for (lp = (char_u *)reg_prev_sub; *lp != NUL; MB_CPTR_ADV(lp)) {
+    for (lp = (uint8_t *)reg_prev_sub; *lp != NUL; MB_CPTR_ADV(lp)) {
       EMIT(utf_ptr2char((char *)lp));
-      if (lp != (char_u *)reg_prev_sub) {
+      if (lp != (uint8_t *)reg_prev_sub) {
         EMIT(NFA_CONCAT);
       }
     }
@@ -2217,13 +2217,13 @@ collection:
     // - character classes  NFA_CLASS_*
     // - ranges, two characters followed by NFA_RANGE.
 
-    p = (char_u *)regparse;
-    endp = (char_u *)skip_anyof((char *)p);
+    p = (uint8_t *)regparse;
+    endp = (uint8_t *)skip_anyof((char *)p);
     if (*endp == ']') {
       // Try to reverse engineer character classes. For example,
       // recognize that [0-9] stands for \d and [A-Za-z_] for \h,
       // and perform the necessary substitutions in the NFA.
-      int result = nfa_recognize_char_class((char_u *)regparse, endp, extra == NFA_ADD_NL);
+      int result = nfa_recognize_char_class((uint8_t *)regparse, endp, extra == NFA_ADD_NL);
       if (result != FAIL) {
         if (result >= NFA_FIRST_NL && result <= NFA_LAST_NL) {
           EMIT(result - NFA_ADD_NL);
@@ -2255,7 +2255,7 @@ collection:
       }
       // Emit the OR branches for each character in the []
       emit_range = false;
-      while ((char_u *)regparse < endp) {
+      while ((uint8_t *)regparse < endp) {
         int oldstartc = startc;
         startc = -1;
         got_coll_char = false;
@@ -2362,7 +2362,7 @@ collection:
         // accepts "\t", "\e", etc., but only when the 'l' flag in
         // 'cpoptions' is not included.
         if (*regparse == '\\'
-            && (char_u *)regparse + 1 <= endp
+            && (uint8_t *)regparse + 1 <= endp
             && (vim_strchr(REGEXP_INRANGE, (uint8_t)regparse[1]) != NULL
                 || (!reg_cpo_lit
                     && vim_strchr(REGEXP_ABBR, (uint8_t)regparse[1])
@@ -2927,7 +2927,7 @@ static int nfa_reg(int paren)
 }
 
 #ifdef REGEXP_DEBUG
-static char_u code[50];
+static uint8_t code[50];
 
 static void nfa_set_code(int c)
 {
@@ -3275,11 +3275,11 @@ static void nfa_set_code(int c)
 }
 
 static FILE *log_fd;
-static char_u e_log_open_failed[] =
+static uint8_t e_log_open_failed[] =
   N_("Could not open temporary log file for writing, displaying on stderr... ");
 
 // Print the postfix notation of the current regexp.
-static void nfa_postfix_dump(char_u *expr, int retval)
+static void nfa_postfix_dump(uint8_t *expr, int retval)
 {
   int *p;
   FILE *f;
@@ -3321,7 +3321,7 @@ static void nfa_print_state(FILE *debugf, nfa_state_T *state)
 
 static void nfa_print_state2(FILE *debugf, nfa_state_T *state, garray_T *indent)
 {
-  char_u *p;
+  uint8_t *p;
 
   if (state == NULL) {
     return;
@@ -3330,10 +3330,10 @@ static void nfa_print_state2(FILE *debugf, nfa_state_T *state, garray_T *indent)
   fprintf(debugf, "(%2d)", abs(state->id));
 
   // Output indent
-  p = (char_u *)indent->ga_data;
+  p = (uint8_t *)indent->ga_data;
   if (indent->ga_len >= 3) {
     int last = indent->ga_len - 3;
-    char_u save[2];
+    uint8_t save[2];
 
     strncpy(save, &p[last], 2);  // NOLINT(runtime/printf)
     memcpy(&p[last], "+-", 2);
@@ -3358,9 +3358,9 @@ static void nfa_print_state2(FILE *debugf, nfa_state_T *state, garray_T *indent)
   // grow indent for state->out
   indent->ga_len -= 1;
   if (state->out1) {
-    ga_concat(indent, (char_u *)"| ");
+    ga_concat(indent, (uint8_t *)"| ");
   } else {
-    ga_concat(indent, (char_u *)"  ");
+    ga_concat(indent, (uint8_t *)"  ");
   }
   ga_append(indent, NUL);
 
@@ -3368,7 +3368,7 @@ static void nfa_print_state2(FILE *debugf, nfa_state_T *state, garray_T *indent)
 
   // replace last part of indent for state->out1
   indent->ga_len -= 3;
-  ga_concat(indent, (char_u *)"  ");
+  ga_concat(indent, (uint8_t *)"  ");
   ga_append(indent, NUL);
 
   nfa_print_state2(debugf, state->out1, indent);
@@ -4493,8 +4493,8 @@ static bool sub_equal(regsub_T *sub1, regsub_T *sub2)
   int todo;
   linenr_T s1;
   linenr_T s2;
-  char_u *sp1;
-  char_u *sp2;
+  uint8_t *sp1;
+  uint8_t *sp2;
 
   todo = sub1->in_use > sub2->in_use ? sub1->in_use : sub2->in_use;
   if (REG_MULTI) {
@@ -4789,7 +4789,7 @@ static regsubs_T *addstate(nfa_list_T *l, nfa_state_T *state, regsubs_T *subs_ar
   nfa_thread_T *thread;
   struct multipos save_multipos;
   int save_in_use;
-  char_u *save_ptr;
+  uint8_t *save_ptr;
   int i;
   regsub_T *sub;
   regsubs_T *subs = subs_arg;
@@ -5532,10 +5532,10 @@ static int recursive_regmatch(nfa_state_T *state, nfa_pim_T *pim, nfa_regprog_T
     // bytes if possible.
     if (state->val <= 0) {
       if (REG_MULTI) {
-        rex.line = (char_u *)reg_getline(--rex.lnum);
+        rex.line = (uint8_t *)reg_getline(--rex.lnum);
         if (rex.line == NULL) {
           // can't go before the first line
-          rex.line = (char_u *)reg_getline(++rex.lnum);
+          rex.line = (uint8_t *)reg_getline(++rex.lnum);
         }
       }
       rex.input = rex.line;
@@ -5543,10 +5543,10 @@ static int recursive_regmatch(nfa_state_T *state, nfa_pim_T *pim, nfa_regprog_T
       if (REG_MULTI && (int)(rex.input - rex.line) < state->val) {
         // Not enough bytes in this line, go to end of
         // previous line.
-        rex.line = (char_u *)reg_getline(--rex.lnum);
+        rex.line = (uint8_t *)reg_getline(--rex.lnum);
         if (rex.line == NULL) {
           // can't go before the first line
-          rex.line = (char_u *)reg_getline(++rex.lnum);
+          rex.line = (uint8_t *)reg_getline(++rex.lnum);
           rex.input = rex.line;
         } else {
           rex.input = rex.line + strlen((char *)rex.line);
@@ -5605,7 +5605,7 @@ static int recursive_regmatch(nfa_state_T *state, nfa_pim_T *pim, nfa_regprog_T
   // restore position in input text
   rex.lnum = save_reglnum;
   if (REG_MULTI) {
-    rex.line = (char_u *)reg_getline(rex.lnum);
+    rex.line = (uint8_t *)reg_getline(rex.lnum);
   }
   rex.input = rex.line + save_reginput_col;
   if (result != NFA_TOO_EXPENSIVE) {
@@ -5782,7 +5782,7 @@ static int failure_chance(nfa_state_T *state, int depth)
 // Skip until the char "c" we know a match must start with.
 static int skip_to_start(int c, colnr_T *colp)
 {
-  const char_u *const s = (char_u *)cstrchr((char *)rex.line + *colp, c);
+  const uint8_t *const s = (uint8_t *)cstrchr((char *)rex.line + *colp, c);
   if (s == NULL) {
     return FAIL;
   }
@@ -5793,7 +5793,7 @@ static int skip_to_start(int c, colnr_T *colp)
 // Check for a match with match_text.
 // Called after skip_to_start() has found regstart.
 // Returns zero for no match, 1 for a match.
-static long find_match_text(colnr_T *startcol, int regstart, char_u *match_text)
+static long find_match_text(colnr_T *startcol, int regstart, uint8_t *match_text)
 {
 #define PTR2LEN(x) utf_ptr2len(x)
 
@@ -5802,8 +5802,8 @@ static long find_match_text(colnr_T *startcol, int regstart, char_u *match_text)
 
   for (;;) {
     bool match = true;
-    char_u *s1 = match_text;
-    char_u *s2 = rex.line + col + regstart_len;  // skip regstart
+    uint8_t *s1 = match_text;
+    uint8_t *s2 = rex.line + col + regstart_len;  // skip regstart
     while (*s1) {
       int c1_len = PTR2LEN((char *)s1);
       int c1 = utf_ptr2char((char *)s1);
@@ -6870,7 +6870,7 @@ static int nfa_regmatch(nfa_regprog_T *prog, nfa_state_T *start, regsubs_T *subm
 
         // Line may have been freed, get it again.
         if (REG_MULTI) {
-          rex.line = (char_u *)reg_getline(rex.lnum);
+          rex.line = (uint8_t *)reg_getline(rex.lnum);
           rex.input = rex.line + col;
         }
 
@@ -7308,15 +7308,15 @@ static long nfa_regtry(nfa_regprog_T *prog, colnr_T col, proftime_T *tm, int *ti
             && mpos->start_lnum == mpos->end_lnum
             && mpos->end_col >= mpos->start_col) {
           re_extmatch_out->matches[i] =
-            (char_u *)xstrnsave((char *)reg_getline(mpos->start_lnum) + mpos->start_col,
-                                (size_t)(mpos->end_col - mpos->start_col));
+            (uint8_t *)xstrnsave((char *)reg_getline(mpos->start_lnum) + mpos->start_col,
+                                 (size_t)(mpos->end_col - mpos->start_col));
         }
       } else {
         struct linepos *lpos = &subs.synt.list.line[i];
 
         if (lpos->start != NULL && lpos->end != NULL) {
           re_extmatch_out->matches[i] =
-            (char_u *)xstrnsave((char *)lpos->start, (size_t)(lpos->end - lpos->start));
+            (uint8_t *)xstrnsave((char *)lpos->start, (size_t)(lpos->end - lpos->start));
         }
       }
     }
@@ -7335,7 +7335,7 @@ static long nfa_regtry(nfa_regprog_T *prog, colnr_T col, proftime_T *tm, int *ti
 ///
 /// @return <= 0 if there is no match and number of lines contained in the
 /// match otherwise.
-static long nfa_regexec_both(char_u *line, colnr_T startcol, proftime_T *tm, int *timed_out)
+static long nfa_regexec_both(uint8_t *line, colnr_T startcol, proftime_T *tm, int *timed_out)
 {
   nfa_regprog_T *prog;
   long retval = 0L;
@@ -7343,13 +7343,13 @@ static long nfa_regexec_both(char_u *line, colnr_T startcol, proftime_T *tm, int
 
   if (REG_MULTI) {
     prog = (nfa_regprog_T *)rex.reg_mmatch->regprog;
-    line = (char_u *)reg_getline((linenr_T)0);  // relative to the cursor
+    line = (uint8_t *)reg_getline((linenr_T)0);  // relative to the cursor
     rex.reg_startpos = rex.reg_mmatch->startpos;
     rex.reg_endpos = rex.reg_mmatch->endpos;
   } else {
     prog = (nfa_regprog_T *)rex.reg_match->regprog;
-    rex.reg_startp = (char_u **)rex.reg_match->startp;
-    rex.reg_endp = (char_u **)rex.reg_match->endp;
+    rex.reg_startp = (uint8_t **)rex.reg_match->startp;
+    rex.reg_endp = (uint8_t **)rex.reg_match->endp;
   }
 
   // Be paranoid...
@@ -7464,7 +7464,7 @@ theend:
 
 // Compile a regular expression into internal code for the NFA matcher.
 // Returns the program in allocated space.  Returns NULL for an error.
-static regprog_T *nfa_regcomp(char_u *expr, int re_flags)
+static regprog_T *nfa_regcomp(uint8_t *expr, int re_flags)
 {
   nfa_regprog_T *prog = NULL;
   int *postfix;
@@ -7582,7 +7582,7 @@ static void nfa_regfree(regprog_T *prog)
 /// @param col   column to start looking for match
 ///
 /// @return  <= 0 for failure, number of lines contained in the match otherwise.
-static int nfa_regexec_nl(regmatch_T *rmp, char_u *line, colnr_T col, bool line_lbr)
+static int nfa_regexec_nl(regmatch_T *rmp, uint8_t *line, colnr_T col, bool line_lbr)
 {
   rex.reg_match = rmp;
   rex.reg_mmatch = NULL;
diff --git a/src/nvim/search.c b/src/nvim/search.c
index ea62a94f28..12fdfa8f4d 100644
--- a/src/nvim/search.c
+++ b/src/nvim/search.c
@@ -3637,9 +3637,9 @@ void find_pattern_in_path(char *ptr, Direction dir, size_t len, bool whole, bool
                                            1L, p_fname);
       } else {
         // Use text after match with 'include'.
-        new_fname = (char *)file_name_in_line(incl_regmatch.endp[0], 0,
-                                              FNAME_EXP|FNAME_INCL|FNAME_REL, 1L, p_fname,
-                                              NULL);
+        new_fname = file_name_in_line(incl_regmatch.endp[0], 0,
+                                      FNAME_EXP|FNAME_INCL|FNAME_REL, 1L, p_fname,
+                                      NULL);
       }
       already_searched = false;
       if (new_fname != NULL) {
diff --git a/src/nvim/spell.c b/src/nvim/spell.c
index e4c5779a08..215c546f83 100644
--- a/src/nvim/spell.c
+++ b/src/nvim/spell.c
@@ -664,7 +664,7 @@ static void find_word(matchinf_T *mip, int mode)
         // For multi-byte chars check character length against
         // COMPOUNDMIN.
         if (slang->sl_compminlen > 0
-            && mb_charlen_len((char_u *)mip->mi_word + mip->mi_compoff,
+            && mb_charlen_len(mip->mi_word + mip->mi_compoff,
                               wlen - mip->mi_compoff) < slang->sl_compminlen) {
           continue;
         }
diff --git a/src/nvim/spellfile.c b/src/nvim/spellfile.c
index 4725c9aea6..1224e9cb9a 100644
--- a/src/nvim/spellfile.c
+++ b/src/nvim/spellfile.c
@@ -270,10 +270,6 @@
 #include "nvim/undo.h"
 #include "nvim/vim.h"
 
-#ifndef UNIX            // it's in os/unix_defs.h for Unix
-# include <time.h>
-#endif
-
 // Special byte values for <byte>.  Some are only used in the tree for
 // postponed prefixes, some only in the other trees.  This is a bit messy...
 enum {
diff --git a/src/nvim/strings.c b/src/nvim/strings.c
index 53b4d7082b..34b3c38103 100644
--- a/src/nvim/strings.c
+++ b/src/nvim/strings.c
@@ -167,7 +167,7 @@ char *vim_strsave_shellescape(const char *string, bool do_special, bool do_newli
 
   // First count the number of extra bytes required.
   size_t length = strlen(string) + 3;       // two quotes and a trailing NUL
-  for (const char_u *p = (char_u *)string; *p != NUL; MB_PTR_ADV(p)) {
+  for (const char *p = string; *p != NUL; MB_PTR_ADV(p)) {
 #ifdef MSWIN
     if (!p_ssl) {
       if (*p == '"') {
@@ -185,7 +185,7 @@ char *vim_strsave_shellescape(const char *string, bool do_special, bool do_newli
         length++;                       // insert backslash
       }
     }
-    if (do_special && find_cmdline_var((char *)p, &l) >= 0) {
+    if (do_special && find_cmdline_var(p, &l) >= 0) {
       length++;                         // insert backslash
       p += l - 1;
     }
@@ -270,7 +270,7 @@ char *vim_strsave_up(const char *string)
   char *p1;
 
   p1 = xstrdup(string);
-  vim_strup((char_u *)p1);
+  vim_strup(p1);
   return p1;
 }
 
@@ -280,17 +280,17 @@ char *vim_strnsave_up(const char *string, size_t len)
   FUNC_ATTR_NONNULL_RET FUNC_ATTR_MALLOC FUNC_ATTR_NONNULL_ALL
 {
   char *p1 = xstrnsave(string, len);
-  vim_strup((char_u *)p1);
+  vim_strup(p1);
   return p1;
 }
 
 // ASCII lower-to-upper case translation, language independent.
-void vim_strup(char_u *p)
+void vim_strup(char *p)
   FUNC_ATTR_NONNULL_ALL
 {
-  char_u c;
-  while ((c = *p) != NUL) {
-    *p++ = (char_u)(c < 'a' || c > 'z' ? c : c - 0x20);
+  uint8_t c;
+  while ((c = (uint8_t)(*p)) != NUL) {
+    *p++ = (char)(uint8_t)(c < 'a' || c > 'z' ? c : c - 0x20);
   }
 }
 
@@ -313,7 +313,7 @@ char *strcase_save(const char *const orig, bool upper)
     int l = utf_ptr2len(p);
     if (c == 0) {
       // overlong sequence, use only the first byte
-      c = (char_u)(*p);
+      c = (uint8_t)(*p);
       l = 1;
     }
     int uc = upper ? mb_toupper(c) : mb_tolower(c);
diff --git a/src/nvim/syntax.c b/src/nvim/syntax.c
index 46cd6245a7..edf44b816f 100644
--- a/src/nvim/syntax.c
+++ b/src/nvim/syntax.c
@@ -1490,8 +1490,8 @@ int get_syntax_attr(const colnr_T col, bool *const can_spell, const bool keep_st
 static int syn_current_attr(const bool syncing, const bool displaying, bool *const can_spell,
                             const bool keep_state)
 {
-  lpos_T endpos;                // was: char_u *endp;
-  lpos_T hl_startpos;           // was: int hl_startcol;
+  lpos_T endpos;
+  lpos_T hl_startpos;
   lpos_T hl_endpos;
   lpos_T eos_pos;               // end-of-start match (start region)
   lpos_T eoe_pos;               // end-of-end pattern
diff --git a/src/nvim/tag.c b/src/nvim/tag.c
index 0d52f73ce7..18c7684584 100644
--- a/src/nvim/tag.c
+++ b/src/nvim/tag.c
@@ -2563,7 +2563,7 @@ int get_tagfname(tagname_T *tnp, int first, char *buf)
   if (first) {
     // Init.  We make a copy of 'tags', because autocommands may change
     // the value without notifying us.
-    tnp->tn_tags = xstrdup((*curbuf->b_p_tags != NUL) ? curbuf->b_p_tags : (char *)p_tags);
+    tnp->tn_tags = xstrdup((*curbuf->b_p_tags != NUL) ? curbuf->b_p_tags : p_tags);
     tnp->tn_np = tnp->tn_tags;
   }
 
@@ -2593,7 +2593,7 @@ int get_tagfname(tagname_T *tnp, int first, char *buf)
       buf[0] = NUL;
       (void)copy_option_part(&tnp->tn_np, buf, MAXPATHL - 1, " ,");
 
-      r_ptr = (char *)vim_findfile_stopdir(buf);
+      r_ptr = vim_findfile_stopdir(buf);
       // move the filename one char forward and truncate the
       // filepath with a NUL
       filename = path_tail(buf);
diff --git a/src/nvim/testing.c b/src/nvim/testing.c
index e9bad2a0b3..d168e67957 100644
--- a/src/nvim/testing.c
+++ b/src/nvim/testing.c
@@ -68,15 +68,15 @@ static void prepare_assert_error(garray_T *gap)
 
 /// Append "p[clen]" to "gap", escaping unprintable characters.
 /// Changes NL to \n, CR to \r, etc.
-static void ga_concat_esc(garray_T *gap, const char_u *p, int clen)
+static void ga_concat_esc(garray_T *gap, const char *p, int clen)
   FUNC_ATTR_NONNULL_ALL
 {
-  char_u buf[NUMBUFLEN];
+  char buf[NUMBUFLEN];
 
   if (clen > 1) {
     memmove(buf, p, (size_t)clen);
     buf[clen] = NUL;
-    ga_concat(gap, (char *)buf);
+    ga_concat(gap, buf);
   } else {
     switch (*p) {
     case BS:
@@ -94,11 +94,11 @@ static void ga_concat_esc(garray_T *gap, const char_u *p, int clen)
     case '\\':
       ga_concat(gap, "\\\\"); break;
     default:
-      if (*p < ' ' || *p == 0x7f) {
-        vim_snprintf((char *)buf, NUMBUFLEN, "\\x%02x", *p);
-        ga_concat(gap, (char *)buf);
+      if ((uint8_t)(*p) < ' ' || *p == 0x7f) {
+        vim_snprintf(buf, NUMBUFLEN, "\\x%02x", *p);
+        ga_concat(gap, buf);
       } else {
-        ga_append(gap, (char)(*p));
+        ga_append(gap, *p);
       }
       break;
     }
@@ -107,21 +107,21 @@ static void ga_concat_esc(garray_T *gap, const char_u *p, int clen)
 
 /// Append "str" to "gap", escaping unprintable characters.
 /// Changes NL to \n, CR to \r, etc.
-static void ga_concat_shorten_esc(garray_T *gap, const char_u *str)
+static void ga_concat_shorten_esc(garray_T *gap, const char *str)
   FUNC_ATTR_NONNULL_ARG(1)
 {
-  char_u buf[NUMBUFLEN];
+  char buf[NUMBUFLEN];
 
   if (str == NULL) {
     ga_concat(gap, "NULL");
     return;
   }
 
-  for (const char_u *p = str; *p != NUL; p++) {
+  for (const char *p = str; *p != NUL; p++) {
     int same_len = 1;
-    const char *s = (char *)p;
+    const char *s = p;
     const int c = mb_ptr2char_adv(&s);
-    const int clen = (int)((char_u *)s - p);
+    const int clen = (int)(s - p);
     while (*s != NUL && c == utf_ptr2char(s)) {
       same_len++;
       s += clen;
@@ -130,10 +130,10 @@ static void ga_concat_shorten_esc(garray_T *gap, const char_u *str)
       ga_concat(gap, "\\[");
       ga_concat_esc(gap, p, clen);
       ga_concat(gap, " occurs ");
-      vim_snprintf((char *)buf, NUMBUFLEN, "%d", same_len);
-      ga_concat(gap, (char *)buf);
+      vim_snprintf(buf, NUMBUFLEN, "%d", same_len);
+      ga_concat(gap, buf);
       ga_concat(gap, " times]");
-      p = (char_u *)s - 1;
+      p = s - 1;
     } else {
       ga_concat_esc(gap, p, clen);
     }
@@ -141,10 +141,10 @@ static void ga_concat_shorten_esc(garray_T *gap, const char_u *str)
 }
 
 /// Fill "gap" with information about an assert error.
-static void fill_assert_error(garray_T *gap, typval_T *opt_msg_tv, char_u *exp_str,
+static void fill_assert_error(garray_T *gap, typval_T *opt_msg_tv, char *exp_str,
                               typval_T *exp_tv_arg, typval_T *got_tv_arg, assert_type_T atype)
 {
-  char_u *tofree;
+  char *tofree;
   typval_T *exp_tv = exp_tv_arg;
   typval_T *got_tv = got_tv_arg;
   bool did_copy = false;
@@ -154,8 +154,8 @@ static void fill_assert_error(garray_T *gap, typval_T *opt_msg_tv, char_u *exp_s
       && !(opt_msg_tv->v_type == VAR_STRING
            && (opt_msg_tv->vval.v_string == NULL
                || *opt_msg_tv->vval.v_string == NUL))) {
-    tofree = (char_u *)encode_tv2echo(opt_msg_tv, NULL);
-    ga_concat(gap, (char *)tofree);
+    tofree = encode_tv2echo(opt_msg_tv, NULL);
+    ga_concat(gap, tofree);
     xfree(tofree);
     ga_concat(gap, ": ");
   }
@@ -218,7 +218,7 @@ static void fill_assert_error(garray_T *gap, typval_T *opt_msg_tv, char_u *exp_s
       }
     }
 
-    tofree = (char_u *)encode_tv2string(exp_tv, NULL);
+    tofree = encode_tv2string(exp_tv, NULL);
     ga_concat_shorten_esc(gap, tofree);
     xfree(tofree);
   } else {
@@ -233,7 +233,7 @@ static void fill_assert_error(garray_T *gap, typval_T *opt_msg_tv, char_u *exp_s
     } else {
       ga_concat(gap, " but got ");
     }
-    tofree = (char_u *)encode_tv2string(got_tv, NULL);
+    tofree = encode_tv2string(got_tv, NULL);
     ga_concat_shorten_esc(gap, tofree);
     xfree(tofree);
 
@@ -306,7 +306,7 @@ static int assert_bool(typval_T *argvars, bool is_true)
                                 : kBoolVarFalse)))) {
     prepare_assert_error(&ga);
     fill_assert_error(&ga, &argvars[1],
-                      (char_u *)(is_true ? "True" : "False"),
+                      is_true ? "True" : "False",
                       NULL, &argvars[0], ASSERT_OTHER);
     assert_error(&ga);
     ga_clear(&ga);
@@ -642,8 +642,8 @@ static int assert_inrange(typval_T *argvars)
       garray_T ga;
       prepare_assert_error(&ga);
       if (argvars[3].v_type != VAR_UNKNOWN) {
-        char_u *const tofree = (char_u *)encode_tv2string(&argvars[3], NULL);
-        ga_concat(&ga, (char *)tofree);
+        char *const tofree = encode_tv2string(&argvars[3], NULL);
+        ga_concat(&ga, tofree);
         xfree(tofree);
       } else {
         char msg[80];
@@ -671,7 +671,7 @@ static int assert_inrange(typval_T *argvars)
       vim_snprintf(msg, sizeof(msg),
                    "range %" PRIdVARNUMBER " - %" PRIdVARNUMBER ",",
                    lower, upper);  // -V576
-      fill_assert_error(&ga, &argvars[3], (char_u *)msg, NULL, &argvars[2],
+      fill_assert_error(&ga, &argvars[3], msg, NULL, &argvars[2],
                         ASSERT_INRANGE);
       assert_error(&ga);
       ga_clear(&ga);
diff --git a/src/nvim/textobject.c b/src/nvim/textobject.c
index 8d58966f46..8e786c271c 100644
--- a/src/nvim/textobject.c
+++ b/src/nvim/textobject.c
@@ -273,7 +273,7 @@ bool startPS(linenr_T lnum, int para, bool both)
     return true;
   }
   if (*s == '.' && (inmacro(p_sections, s + 1)
-                    || (!para && inmacro((char *)p_para, s + 1)))) {
+                    || (!para && inmacro(p_para, s + 1)))) {
     return true;
   }
   return false;
@@ -1078,7 +1078,7 @@ static bool in_html_tag(bool end_tag)
     if (inc(&pos) < 0) {
       return false;
     }
-    c = *ml_get_pos(&pos);
+    c = (uint8_t)(*ml_get_pos(&pos));
     if (c == '>') {
       break;
     }
diff --git a/src/nvim/undo.c b/src/nvim/undo.c
index ad16a6eda2..7dd1e9b05d 100644
--- a/src/nvim/undo.c
+++ b/src/nvim/undo.c
@@ -624,7 +624,7 @@ int u_savecommon(buf_T *buf, linenr_T top, linenr_T bot, linenr_T newbot, int re
 // extra fields for uhp
 #define UHP_SAVE_NR            1
 
-static char_u e_not_open[] = N_("E828: Cannot open undo file for writing: %s");
+static char e_not_open[] = N_("E828: Cannot open undo file for writing: %s");
 
 /// Compute the hash for a buffer text into hash[UNDO_HASH_SIZE].
 ///
@@ -677,7 +677,7 @@ char *u_get_undo_file_name(const char *const buf_ffname, const bool reading)
 
   // Loop over 'undodir'.  When reading find the first file that exists.
   // When not reading use the first directory that exists or ".".
-  char *dirp = (char *)p_udir;
+  char *dirp = p_udir;
   while (*dirp != NUL) {
     size_t dir_len = copy_option_part(&dirp, dir_name, MAXPATHL, ",");
     if (dir_len == 1 && dir_name[0] == '.') {
diff --git a/src/nvim/window.c b/src/nvim/window.c
index fdaaeb812e..92d11cef0a 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -6790,17 +6790,17 @@ char *grab_file_name(long count, linenr_T *file_lnum)
 // FNAME_INCL       apply "includeexpr"
 char *file_name_at_cursor(int options, long count, linenr_T *file_lnum)
 {
-  return (char *)file_name_in_line(get_cursor_line_ptr(),
-                                   curwin->w_cursor.col, options, count, curbuf->b_ffname,
-                                   file_lnum);
+  return file_name_in_line(get_cursor_line_ptr(),
+                           curwin->w_cursor.col, options, count, curbuf->b_ffname,
+                           file_lnum);
 }
 
 /// @param rel_fname  file we are searching relative to
 /// @param file_lnum  line number after the file name
 ///
 /// @return  the name of the file under or after ptr[col]. Otherwise like file_name_at_cursor().
-char_u *file_name_in_line(char *line, int col, int options, long count, char *rel_fname,
-                          linenr_T *file_lnum)
+char *file_name_in_line(char *line, int col, int options, long count, char *rel_fname,
+                        linenr_T *file_lnum)
 {
   // search forward for what could be the start of a file name
   char *ptr = line + col;
@@ -6888,7 +6888,7 @@ char_u *file_name_in_line(char *line, int col, int options, long count, char *re
     }
   }
 
-  return (char_u *)find_file_name_in_path(ptr, len, options, count, rel_fname);
+  return find_file_name_in_path(ptr, len, options, count, rel_fname);
 }
 
 /// Add or remove a status line from window(s), according to the