refactor: replace char_u with char

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

39 files changed, 262 insertions, 275 deletions

diff --git a/src/nvim/arglist.c b/src/nvim/arglist.c
index 0000636417..02e3a99aab 100644
--- a/src/nvim/arglist.c
+++ b/src/nvim/arglist.c
@@ -633,7 +633,7 @@ void ex_argdedupe(exarg_T *eap FUNC_ATTR_UNUSED)
 {
   for (int i = 0; i < ARGCOUNT; i++) {
     for (int j = i + 1; j < ARGCOUNT; j++) {
-      if (FNAMECMP(ARGLIST[i].ae_fname, ARGLIST[j].ae_fname) == 0) {
+      if (path_fnamecmp(ARGLIST[i].ae_fname, ARGLIST[j].ae_fname) == 0) {
         xfree(ARGLIST[j].ae_fname);
         memmove(ARGLIST + j, ARGLIST + j + 1,
                 (size_t)(ARGCOUNT - j - 1) * sizeof(aentry_T));
diff --git a/src/nvim/autocmd.c b/src/nvim/autocmd.c
index 635875b16f..9d37647a4e 100644
--- a/src/nvim/autocmd.c
+++ b/src/nvim/autocmd.c
@@ -2396,7 +2396,7 @@ bool au_exists(const char *const arg) FUNC_ATTR_WARN_UNUSED_RESULT
   }
 
   // if pattern is "<buffer>", special handling is needed which uses curbuf
-  // for pattern "<buffer=N>, FNAMECMP() will work fine
+  // for pattern "<buffer=N>, path_fnamecmp() will work fine
   if (pattern != NULL && STRICMP(pattern, "<buffer>") == 0) {
     buflocal_buf = curbuf;
   }
@@ -2404,12 +2404,12 @@ bool au_exists(const char *const arg) FUNC_ATTR_WARN_UNUSED_RESULT
   // Check if there is an autocommand with the given pattern.
   for (; ap != NULL; ap = ap->next) {
     // only use a pattern when it has not been removed and has commands.
-    // For buffer-local autocommands, FNAMECMP() works fine.
+    // For buffer-local autocommands, path_fnamecmp() works fine.
     if (ap->pat != NULL && ap->cmds != NULL
         && (group == AUGROUP_ALL || ap->group == group)
         && (pattern == NULL
             || (buflocal_buf == NULL
-                ? FNAMECMP(ap->pat, pattern) == 0
+                ? path_fnamecmp(ap->pat, pattern) == 0
                 : ap->buflocal_nr == buflocal_buf->b_fnum))) {
       retval = true;
       break;
diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index 658d372cee..1cc68c9cee 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -2733,7 +2733,7 @@ void buflist_list(exarg_T *eap)
       IObuff[len++] = ' ';
     } while (--i > 0 && len < IOSIZE - 18);
     if (vim_strchr(eap->arg, 't') && buf->b_last_used) {
-      undo_fmt_time(IObuff + len, (size_t)(IOSIZE - len), buf->b_last_used);
+      undo_fmt_time((char_u *)IObuff + len, (size_t)(IOSIZE - len), buf->b_last_used);
     } else {
       vim_snprintf((char *)IObuff + len, (size_t)(IOSIZE - len), _("line %" PRId64),
                    buf == curbuf ? (int64_t)curwin->w_cursor.lnum : (int64_t)buflist_findlnum(buf));
@@ -2965,7 +2965,7 @@ static bool otherfile_buf(buf_T *buf, char *ffname, FileID *file_id_p, bool file
   if (ffname == NULL || *ffname == NUL || buf->b_ffname == NULL) {
     return true;
   }
-  if (FNAMECMP(ffname, buf->b_ffname) == 0) {
+  if (path_fnamecmp(ffname, buf->b_ffname) == 0) {
     return false;
   }
   {
diff --git a/src/nvim/cmdexpand.c b/src/nvim/cmdexpand.c
index d2cfb25bf9..3e9edea372 100644
--- a/src/nvim/cmdexpand.c
+++ b/src/nvim/cmdexpand.c
@@ -361,7 +361,7 @@ static char *ExpandOne_start(int mode, expand_T *xp, char *str, int options)
         // expand_wildcards, only need to check the first two.
         non_suf_match = 0;
         for (int i = 0; i < 2; i++) {
-          if (match_suffix((char_u *)xp->xp_files[i])) {
+          if (match_suffix(xp->xp_files[i])) {
             non_suf_match++;
           }
         }
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 0f2547120d..ead01fcbad 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -8117,7 +8117,7 @@ repeat:
 
         // Do not call shorten_fname() here since it removes the prefix
         // even though the path does not have a prefix.
-        if (FNAMENCMP(p, dirname, namelen) == 0) {
+        if (path_fnamencmp(p, dirname, namelen) == 0) {
           p += namelen;
           if (vim_ispathsep(*p)) {
             while (*p && vim_ispathsep(*p)) {
@@ -8329,7 +8329,7 @@ char *do_string_sub(char *str, char *pat, char *sub, typval_T *expr, char *flags
     while (vim_regexec_nl(&regmatch, (char_u *)str, (colnr_T)(tail - str))) {
       // Skip empty match except for first match.
       if (regmatch.startp[0] == regmatch.endp[0]) {
-        if ((char_u *)zero_width == regmatch.startp[0]) {
+        if (zero_width == regmatch.startp[0]) {
           // avoid getting stuck on a match with an empty string
           int i = utfc_ptr2len(tail);
           memmove((char_u *)ga.ga_data + ga.ga_len, tail, (size_t)i);
@@ -8337,7 +8337,7 @@ char *do_string_sub(char *str, char *pat, char *sub, typval_T *expr, char *flags
           tail += i;
           continue;
         }
-        zero_width = (char *)regmatch.startp[0];
+        zero_width = regmatch.startp[0];
       }
 
       // Get some space for a temporary buffer to do the substitution
@@ -8350,14 +8350,14 @@ char *do_string_sub(char *str, char *pat, char *sub, typval_T *expr, char *flags
                          (regmatch.endp[0] - regmatch.startp[0])));
 
       // copy the text up to where the match is
-      int i = (int)(regmatch.startp[0] - (char_u *)tail);
+      int i = (int)(regmatch.startp[0] - tail);
       memmove((char_u *)ga.ga_data + ga.ga_len, tail, (size_t)i);
       // add the substituted text
       (void)vim_regsub(&regmatch, (char_u *)sub, expr,
                        (char_u *)ga.ga_data + ga.ga_len + i, sublen,
                        REGSUB_COPY | REGSUB_MAGIC);
       ga.ga_len += i + sublen - 1;
-      tail = (char *)regmatch.endp[0];
+      tail = regmatch.endp[0];
       if (*tail == NUL) {
         break;
       }
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index fa48f227e3..b59caab34f 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -4984,9 +4984,9 @@ static void find_some_match(typval_T *const argvars, typval_T *const rettv,
         li = TV_LIST_ITEM_NEXT(l, li);
         idx++;
       } else {
-        startcol = (colnr_T)(regmatch.startp[0]
-                             + utfc_ptr2len((char *)regmatch.startp[0]) - str);
-        if (startcol > (colnr_T)len || str + startcol <= regmatch.startp[0]) {
+        startcol = (colnr_T)((char_u *)regmatch.startp[0]
+                             + utfc_ptr2len(regmatch.startp[0]) - str);
+        if (startcol > (colnr_T)len || str + startcol <= (char_u *)regmatch.startp[0]) {
           match = false;
           break;
         }
@@ -5005,8 +5005,8 @@ static void find_some_match(typval_T *const argvars, typval_T *const rettv,
 
         const size_t rd = (size_t)(regmatch.endp[0] - regmatch.startp[0]);
         TV_LIST_ITEM_TV(li1)->vval.v_string = xmemdupz((const char *)regmatch.startp[0], rd);
-        TV_LIST_ITEM_TV(li3)->vval.v_number = (varnumber_T)(regmatch.startp[0] - expr);
-        TV_LIST_ITEM_TV(li4)->vval.v_number = (varnumber_T)(regmatch.endp[0] - expr);
+        TV_LIST_ITEM_TV(li3)->vval.v_number = (varnumber_T)((char_u *)regmatch.startp[0] - expr);
+        TV_LIST_ITEM_TV(li4)->vval.v_number = (varnumber_T)(regmatch.endp[0] - (char *)expr);
         if (l != NULL) {
           TV_LIST_ITEM_TV(li2)->vval.v_number = (varnumber_T)idx;
         }
@@ -5041,10 +5041,10 @@ static void find_some_match(typval_T *const argvars, typval_T *const rettv,
         } else {
           if (type == kSomeMatch) {
             rettv->vval.v_number =
-              (varnumber_T)(regmatch.startp[0] - str);
+              (varnumber_T)((char_u *)regmatch.startp[0] - str);
           } else {
             rettv->vval.v_number =
-              (varnumber_T)(regmatch.endp[0] - str);
+              (varnumber_T)(regmatch.endp[0] - (char *)str);
           }
           rettv->vval.v_number += (varnumber_T)(str - expr);
         }
@@ -6225,8 +6225,8 @@ static void f_rename(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
     rettv->vval.v_number = -1;
   } else {
     char buf[NUMBUFLEN];
-    rettv->vval.v_number = vim_rename((const char_u *)tv_get_string(&argvars[0]),
-                                      (const char_u *)tv_get_string_buf(&argvars[1], buf));
+    rettv->vval.v_number = vim_rename(tv_get_string(&argvars[0]),
+                                      tv_get_string_buf(&argvars[1], buf));
   }
 }
 
@@ -8193,11 +8193,11 @@ static void f_split(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
         break;
       }
       // Advance to just after the match.
-      if (regmatch.endp[0] > (char_u *)str) {
+      if (regmatch.endp[0] > str) {
         col = 0;
       } else {
         // Don't get stuck at the same match.
-        col = utfc_ptr2len((char *)regmatch.endp[0]);
+        col = utfc_ptr2len(regmatch.endp[0]);
       }
       str = (const char *)regmatch.endp[0];
     }
diff --git a/src/nvim/eval/userfunc.c b/src/nvim/eval/userfunc.c
index a1c4b8b893..70c9e02d5c 100644
--- a/src/nvim/eval/userfunc.c
+++ b/src/nvim/eval/userfunc.c
@@ -2462,7 +2462,7 @@ void ex_function(exarg_T *eap)
         p = vim_strchr((char *)scriptname, '/');
         plen = (int)STRLEN(p);
         slen = (int)STRLEN(SOURCING_NAME);
-        if (slen > plen && FNAMECMP(p, SOURCING_NAME + slen - plen) == 0) {
+        if (slen > plen && path_fnamecmp(p, SOURCING_NAME + slen - plen) == 0) {
           j = OK;
         }
         xfree(scriptname);
@@ -2632,7 +2632,7 @@ char *get_user_func_name(expand_T *xp, int idx)
       return (char *)fp->uf_name;  // Prevent overflow.
     }
 
-    cat_func_name(IObuff, fp);
+    cat_func_name((char_u *)IObuff, fp);
     if (xp->xp_context != EXPAND_USER_FUNC) {
       STRCAT(IObuff, "(");
       if (!fp->uf_varargs && GA_EMPTY(&fp->uf_args)) {
diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index 4f33a2d883..96bef4902c 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -559,10 +559,10 @@ void ex_sort(exarg_T *eap)
     end_col = len;
     if (regmatch.regprog != NULL && vim_regexec(&regmatch, s, 0)) {
       if (sort_rx) {
-        start_col = (colnr_T)(regmatch.startp[0] - (char_u *)s);
-        end_col = (colnr_T)(regmatch.endp[0] - (char_u *)s);
+        start_col = (colnr_T)(regmatch.startp[0] - s);
+        end_col = (colnr_T)(regmatch.endp[0] - s);
       } else {
-        start_col = (colnr_T)(regmatch.endp[0] - (char_u *)s);
+        start_col = (colnr_T)(regmatch.endp[0] - s);
       }
     } else if (regmatch.regprog != NULL) {
       end_col = 0;
diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index 2a378f6f02..5defabc05a 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -2836,12 +2836,12 @@ static void append_command(char *cmd)
   }
   STRCAT(IObuff, ": ");
   d = (char *)IObuff + STRLEN(IObuff);
-  while (*s != NUL && (char_u *)d - IObuff + 5 < IOSIZE) {
+  while (*s != NUL && d - IObuff + 5 < IOSIZE) {
     if ((char_u)s[0] == 0xc2 && (char_u)s[1] == 0xa0) {
       s += 2;
       STRCPY(d, "<a0>");
       d += 4;
-    } else if ((char_u *)d - IObuff + utfc_ptr2len(s) + 1 >= IOSIZE) {
+    } else if (d - IObuff + utfc_ptr2len(s) + 1 >= IOSIZE) {
       break;
     } else {
       mb_copy_char((const char **)&s, &d);
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index 60c89f61a8..2b7797ddc8 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -2005,7 +2005,7 @@ static int command_line_handle_key(CommandLineState *s)
   } else {
     int j = utf_char2bytes(s->c, (char *)IObuff);
     IObuff[j] = NUL;                // exclude composing chars
-    put_on_cmdline(IObuff, j, true);
+    put_on_cmdline((char_u *)IObuff, j, true);
   }
   return command_line_changed(s);
 }
diff --git a/src/nvim/file_search.c b/src/nvim/file_search.c
index 5416be651d..b3491e98c2 100644
--- a/src/nvim/file_search.c
+++ b/src/nvim/file_search.c
@@ -112,7 +112,7 @@ typedef struct ff_visited {
   FileID file_id;
   // The memory for this struct is allocated according to the length of
   // ffv_fname.
-  char_u ffv_fname[1];                  // actually longer
+  char ffv_fname[1];                  // actually longer
 } ff_visited_T;
 
 // We might have to manage several visited lists during a search.
@@ -463,7 +463,7 @@ void *vim_findfile_init(char *path, char *filename, char *stopdirs, int level, i
           xfree(buf);
           goto error_return;
         }
-        STRLCAT(ff_expand_buffer, search_ctx->ffsc_fix_path, eb_len + (size_t)len + 1);
+        xstrlcat(ff_expand_buffer, search_ctx->ffsc_fix_path, eb_len + (size_t)len + 1);
         add_pathsep(ff_expand_buffer);
       } else {
         len = (int)STRLEN(search_ctx->ffsc_fix_path);
@@ -813,8 +813,7 @@ char_u *vim_findfile(void *search_ctx_arg)
                 }
                 if (os_dirname((char_u *)ff_expand_buffer, MAXPATHL)
                     == OK) {
-                  p = path_shorten_fname(file_path,
-                                         (char_u *)ff_expand_buffer);
+                  p = (char_u *)path_shorten_fname((char *)file_path, ff_expand_buffer);
                   if (p != NULL) {
                     STRMOVE(file_path, p);
                   }
@@ -859,8 +858,8 @@ char_u *vim_findfile(void *search_ctx_arg)
       if (STRNCMP(stackp->ffs_wc_path, "**", 2) == 0) {
         for (int i = stackp->ffs_filearray_cur;
              i < stackp->ffs_filearray_size; i++) {
-          if (FNAMECMP(stackp->ffs_filearray[i],
-                       stackp->ffs_fix_path) == 0) {
+          if (path_fnamecmp(stackp->ffs_filearray[i],
+                            (char *)stackp->ffs_fix_path) == 0) {
             continue;             // don't repush same directory
           }
           if (!os_isdir(stackp->ffs_filearray[i])) {
@@ -883,9 +882,9 @@ char_u *vim_findfile(void *search_ctx_arg)
       ff_stack_T *sptr;
 
       // is the last starting directory in the stop list?
-      if (ff_path_in_stoplist((char_u *)search_ctx->ffsc_start_dir,
+      if (ff_path_in_stoplist(search_ctx->ffsc_start_dir,
                               (int)(path_end - (char_u *)search_ctx->ffsc_start_dir),
-                              (char_u **)search_ctx->ffsc_stopdirs_v) == true) {
+                              search_ctx->ffsc_stopdirs_v) == true) {
         break;
       }
 
@@ -981,7 +980,7 @@ static ff_visited_list_hdr_T *ff_get_visited_list(char *filename,
   if (*list_headp != NULL) {
     retptr = *list_headp;
     while (retptr != NULL) {
-      if (FNAMECMP(filename, retptr->ffvl_filename) == 0) {
+      if (path_fnamecmp(filename, retptr->ffvl_filename) == 0) {
 #ifdef FF_VERBOSE
         if (p_verbose >= 5) {
           verbose_enter_scroll();
@@ -1080,7 +1079,7 @@ static int ff_check_visited(ff_visited_T **visited_list, char *fname, char *wc_p
 
   // check against list of already visited files
   for (vp = *visited_list; vp != NULL; vp = vp->ffv_next) {
-    if ((url && FNAMECMP(vp->ffv_fname, ff_expand_buffer) == 0)
+    if ((url && path_fnamecmp(vp->ffv_fname, ff_expand_buffer) == 0)
         || (!url && vp->file_id_valid
             && os_fileid_equal(&(vp->file_id), &file_id))) {
       // are the wildcard parts equal
@@ -1224,7 +1223,7 @@ static void ff_clear(ff_search_ctx_T *search_ctx)
 /// check if the given path is in the stopdirs
 ///
 /// @return  true if yes else false
-static int ff_path_in_stoplist(char_u *path, int path_len, char_u **stopdirs_v)
+static int ff_path_in_stoplist(char *path, int path_len, char **stopdirs_v)
 {
   int i = 0;
 
@@ -1243,12 +1242,12 @@ static int ff_path_in_stoplist(char_u *path, int path_len, char_u **stopdirs_v)
       // match for parent directory. So '/home' also matches
       // '/home/rks'. Check for PATHSEP in stopdirs_v[i], else
       // '/home/r' would also match '/home/rks'
-      if (FNAMENCMP(stopdirs_v[i], path, path_len) == 0
+      if (path_fnamencmp(stopdirs_v[i], path, (size_t)path_len) == 0
           && vim_ispathsep(stopdirs_v[i][path_len])) {
         return true;
       }
     } else {
-      if (FNAMECMP(stopdirs_v[i], path) == 0) {
+      if (path_fnamecmp(stopdirs_v[i], path) == 0) {
         return true;
       }
     }
diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index 7b117aa6e3..0bc7f736bc 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -117,7 +117,7 @@ struct bw_info {
 
 static char *e_auchangedbuf = N_("E812: Autocommands changed buffer or buffer name");
 
-void filemess(buf_T *buf, char_u *name, char_u *s, int attr)
+void filemess(buf_T *buf, char *name, char *s, int attr)
 {
   int msg_scroll_save;
 
@@ -126,7 +126,7 @@ void filemess(buf_T *buf, char_u *name, char_u *s, int attr)
   }
   add_quoted_fname((char *)IObuff, IOSIZE - 100, buf, (const char *)name);
   // Avoid an over-long translation to cause trouble.
-  STRLCAT(IObuff, s, IOSIZE);
+  xstrlcat(IObuff, s, IOSIZE);
   // For the first message may have to start a new line.
   // For further ones overwrite the previous one, reset msg_scroll before
   // calling filemess().
@@ -350,7 +350,7 @@ int readfile(char *fname, char *sfname, linenr_T from, linenr_T lines_to_skip,
 
     // If the name is too long we might crash further on, quit here.
     if (namelen >= MAXPATHL) {
-      filemess(curbuf, (char_u *)fname, (char_u *)_("Illegal file name"), 0);
+      filemess(curbuf, fname, _("Illegal file name"), 0);
       msg_end();
       msg_scroll = msg_save;
       return FAIL;
@@ -361,7 +361,7 @@ int readfile(char *fname, char *sfname, linenr_T from, linenr_T lines_to_skip,
     // swap file may destroy it!  Reported on MS-DOS and Win 95.
     if (after_pathsep(fname, fname + namelen)) {
       if (!silent) {
-        filemess(curbuf, (char_u *)fname, (char_u *)_(msg_is_a_directory), 0);
+        filemess(curbuf, fname, _(msg_is_a_directory), 0);
       }
       msg_end();
       msg_scroll = msg_save;
@@ -383,10 +383,10 @@ int readfile(char *fname, char *sfname, linenr_T from, linenr_T lines_to_skip,
         ) {
       if (S_ISDIR(perm)) {
         if (!silent) {
-          filemess(curbuf, (char_u *)fname, (char_u *)_(msg_is_a_directory), 0);
+          filemess(curbuf, fname, _(msg_is_a_directory), 0);
         }
       } else {
-        filemess(curbuf, (char_u *)fname, (char_u *)_("is not a file"), 0);
+        filemess(curbuf, fname, _("is not a file"), 0);
       }
       msg_end();
       msg_scroll = msg_save;
@@ -475,9 +475,9 @@ int readfile(char *fname, char *sfname, linenr_T from, linenr_T lines_to_skip,
       }
       if (!silent) {
         if (dir_of_file_exists((char_u *)fname)) {
-          filemess(curbuf, (char_u *)sfname, (char_u *)new_file_message(), 0);
+          filemess(curbuf, sfname, new_file_message(), 0);
         } else {
-          filemess(curbuf, (char_u *)sfname, (char_u *)_("[New DIRECTORY]"), 0);
+          filemess(curbuf, sfname, _("[New DIRECTORY]"), 0);
         }
       }
       // Even though this is a new file, it might have been
@@ -497,15 +497,15 @@ int readfile(char *fname, char *sfname, linenr_T from, linenr_T lines_to_skip,
       }
       return OK;                  // a new file is not an error
     } else {
-      filemess(curbuf, (char_u *)sfname, (char_u *)((fd == UV_EFBIG) ? _("[File too big]") :
+      filemess(curbuf, sfname, ((fd == UV_EFBIG) ? _("[File too big]") :
 #if defined(UNIX) && defined(EOVERFLOW)
-                                                    // libuv only returns -errno
-                                                    // in Unix and in Windows
-                                                    // open() does not set
-                                                    // EOVERFLOW
-                                                    (fd == -EOVERFLOW) ? _("[File too big]") :
+                                // libuv only returns -errno
+                                // in Unix and in Windows
+                                // open() does not set
+                                // EOVERFLOW
+                                (fd == -EOVERFLOW) ? _("[File too big]") :
 #endif
-                                                    _("[Permission Denied]")), 0);
+                                _("[Permission Denied]")), 0);
       curbuf->b_p_ro = true;                  // must use "w!" now
     }
 
@@ -661,7 +661,7 @@ int readfile(char *fname, char *sfname, linenr_T from, linenr_T lines_to_skip,
 
   if (!recoverymode && !filtering && !(flags & READ_DUMMY) && !silent) {
     if (!read_stdin && !read_buffer) {
-      filemess(curbuf, (char_u *)sfname, (char_u *)"", 0);
+      filemess(curbuf, sfname, "", 0);
     }
   }
 
@@ -1728,7 +1728,7 @@ failed:
 
     if (got_int) {
       if (!(flags & READ_DUMMY)) {
-        filemess(curbuf, (char_u *)sfname, (char_u *)_(e_interr), 0);
+        filemess(curbuf, sfname, _(e_interr), 0);
         if (newfile) {
           curbuf->b_p_ro = true;                // must use "w!" now
         }
@@ -2253,7 +2253,7 @@ int buf_write(buf_T *buf, char *fname, char *sfname, linenr_T start, linenr_T en
   fname = sfname;
 #endif
 
-  if (buf->b_ffname != NULL && FNAMECMP(ffname, buf->b_ffname) == 0) {
+  if (buf->b_ffname != NULL && path_fnamecmp(ffname, buf->b_ffname) == 0) {
     overwriting = true;
   } else {
     overwriting = false;
@@ -2455,9 +2455,9 @@ int buf_write(buf_T *buf, char *fname, char *sfname, linenr_T start, linenr_T en
 #ifndef UNIX
              (char_u *)sfname,
 #else
-             (char_u *)fname,
+             fname,
 #endif
-             (char_u *)"", 0);               // show that we are busy
+             "", 0);               // show that we are busy
   }
   msg_scroll = false;               // always overwrite the file message now
 
@@ -2596,7 +2596,7 @@ int buf_write(buf_T *buf, char *fname, char *sfname, linenr_T start, linenr_T en
         STRCPY(IObuff, fname);
         for (i = 4913;; i += 123) {
           char *tail = path_tail((char *)IObuff);
-          size_t size = (size_t)((char_u *)tail - IObuff);
+          size_t size = (size_t)(tail - IObuff);
           snprintf(tail, IOSIZE - size, "%d", i);
           if (!os_fileinfo_link((char *)IObuff, &file_info)) {
             break;
@@ -2884,7 +2884,7 @@ nobackup:
           // If the renaming of the original file to the backup file
           // works, quit here.
           ///
-          if (vim_rename((char_u *)fname, (char_u *)backup) == 0) {
+          if (vim_rename(fname, backup) == 0) {
             break;
           }
 
@@ -3100,7 +3100,7 @@ restore_backup:
               // In that case we leave the copy around.
               // If file does not exist, put the copy in its place
               if (!os_path_exists(fname)) {
-                vim_rename((char_u *)backup, (char_u *)fname);
+                vim_rename(backup, fname);
               }
               // if original file does exist throw away the copy
               if (os_path_exists(fname)) {
@@ -3108,7 +3108,7 @@ restore_backup:
               }
             } else {
               // try to put the original file back
-              vim_rename((char_u *)backup, (char_u *)fname);
+              vim_rename(backup, fname);
             }
           }
 
@@ -3375,7 +3375,7 @@ restore_backup:
           end = 1;  // success
         }
       } else {
-        if (vim_rename((char_u *)backup, (char_u *)fname) == 0) {
+        if (vim_rename(backup, fname) == 0) {
           end = 1;
         }
       }
@@ -3471,7 +3471,7 @@ restore_backup:
       if (org == NULL) {
         emsg(_("E205: Patchmode: can't save original file"));
       } else if (!os_path_exists(org)) {
-        vim_rename((char_u *)backup, (char_u *)org);
+        vim_rename(backup, org);
         XFREE_CLEAR(backup);                   // don't delete the file
 #ifdef UNIX
         os_file_settime(org,
@@ -3716,20 +3716,20 @@ void msg_add_lines(int insert_space, long lnum, off_T nchars)
 {
   char_u *p;
 
-  p = IObuff + STRLEN(IObuff);
+  p = (char_u *)IObuff + STRLEN(IObuff);
 
   if (insert_space) {
     *p++ = ' ';
   }
   if (shortmess(SHM_LINES)) {
-    vim_snprintf((char *)p, (size_t)(IOSIZE - (p - IObuff)), "%" PRId64 "L, %" PRId64 "B",
+    vim_snprintf((char *)p, (size_t)(IOSIZE - (p - (char_u *)IObuff)), "%" PRId64 "L, %" PRId64 "B",
                  (int64_t)lnum, (int64_t)nchars);
   } else {
-    vim_snprintf((char *)p, (size_t)(IOSIZE - (p - IObuff)),
+    vim_snprintf((char *)p, (size_t)(IOSIZE - (p - (char_u *)IObuff)),
                  NGETTEXT("%" PRId64 " line, ", "%" PRId64 " lines, ", lnum),
                  (int64_t)lnum);
     p += STRLEN(p);
-    vim_snprintf((char *)p, (size_t)(IOSIZE - (p - IObuff)),
+    vim_snprintf((char *)p, (size_t)(IOSIZE - (p - (char_u *)IObuff)),
                  NGETTEXT("%" PRId64 " byte", "%" PRId64 " bytes", nchars),
                  (int64_t)nchars);
   }
@@ -4189,7 +4189,7 @@ void shorten_buf_fname(buf_T *buf, char_u *dirname, int force)
     if (buf->b_sfname != buf->b_ffname) {
       XFREE_CLEAR(buf->b_sfname);
     }
-    p = (char *)path_shorten_fname((char_u *)buf->b_ffname, dirname);
+    p = path_shorten_fname(buf->b_ffname, (char *)dirname);
     if (p != NULL) {
       buf->b_sfname = xstrdup(p);
       buf->b_fname = buf->b_sfname;
@@ -4481,7 +4481,7 @@ int put_time(FILE *fd, time_t time_)
 /// function will (attempts to?) copy the file across if rename fails -- webb
 ///
 /// @return  -1 for failure, 0 for success
-int vim_rename(const char_u *from, const char_u *to)
+int vim_rename(const char *from, const char *to)
   FUNC_ATTR_NONNULL_ALL
 {
   int fd_in;
@@ -4498,7 +4498,7 @@ int vim_rename(const char_u *from, const char_u *to)
   // When the names are identical, there is nothing to do.  When they refer
   // to the same file (ignoring case and slash/backslash differences) but
   // the file name differs we need to go through a temp file.
-  if (FNAMECMP(from, to) == 0) {
+  if (path_fnamecmp(from, to) == 0) {
     if (p_fic && (strcmp(path_tail((char *)from), path_tail((char *)to))
                   != 0)) {
       use_tmp_file = true;
@@ -4536,13 +4536,13 @@ int vim_rename(const char_u *from, const char_u *to)
       snprintf(tail, (size_t)((MAXPATHL + 1) - (tail - (char *)tempname - 1)), "%d", n);
 
       if (!os_path_exists((char *)tempname)) {
-        if (os_rename(from, tempname) == OK) {
-          if (os_rename(tempname, to) == OK) {
+        if (os_rename((char_u *)from, tempname) == OK) {
+          if (os_rename(tempname, (char_u *)to) == OK) {
             return 0;
           }
           // Strange, the second step failed.  Try mov