Merge #8863 'refactor: Remove mb_head_off() '

20 files changed, 120 insertions, 160 deletions

diff --git a/src/nvim/diff.c b/src/nvim/diff.c
index 878971a35c..4bfe67c9d3 100644
--- a/src/nvim/diff.c
+++ b/src/nvim/diff.c
@@ -1962,12 +1962,10 @@ bool diff_find_change(win_T *wp, linenr_T lnum, int *startp, int *endp)
         }
       }
 
-      if (has_mbyte) {
-        // Move back to first byte of character in both lines (may
-        // have "nn^" in line_org and "n^ in line_new).
-        si_org -= (*mb_head_off)(line_org, line_org + si_org);
-        si_new -= (*mb_head_off)(line_new, line_new + si_new);
-      }
+      // Move back to first byte of character in both lines (may
+      // have "nn^" in line_org and "n^ in line_new).
+      si_org -= utf_head_off(line_org, line_org + si_org);
+      si_new -= utf_head_off(line_new, line_new + si_new);
 
       if (*startp > si_org) {
         *startp = si_org;
diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index 08b74249ba..a20661bb16 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -1556,14 +1556,11 @@ void display_dollar(colnr_T col)
 
   save_col = curwin->w_cursor.col;
   curwin->w_cursor.col = col;
-  if (has_mbyte) {
-    char_u *p;
 
-    /* If on the last byte of a multi-byte move to the first byte. */
-    p = get_cursor_line_ptr();
-    curwin->w_cursor.col -= (*mb_head_off)(p, p + col);
-  }
-  curs_columns(FALSE);              /* recompute w_wrow and w_wcol */
+  // If on the last byte of a multi-byte move to the first byte.
+  char_u *p = get_cursor_line_ptr();
+  curwin->w_cursor.col -= utf_head_off(p, p + col);
+  curs_columns(false);              // Recompute w_wrow and w_wcol
   if (curwin->w_wcol < curwin->w_width) {
     edit_putchar('$', FALSE);
     dollar_vcol = curwin->w_virtcol;
@@ -3448,10 +3445,10 @@ static void ins_compl_fixRedoBufForLeader(char_u *ptr_arg)
   }
   if (compl_orig_text != NULL) {
     p = compl_orig_text;
-    for (len = 0; p[len] != NUL && p[len] == ptr[len]; ++len)
-      ;
-    if (len > 0)
-      len -= (*mb_head_off)(p, p + len);
+    for (len = 0; p[len] != NUL && p[len] == ptr[len]; len++) {}
+    if (len > 0) {
+      len -= utf_head_off(p, p + len);
+    }
     for (p += len; *p != NUL; MB_PTR_ADV(p)) {
       AppendCharToRedobuff(K_BS);
     }
@@ -4587,24 +4584,17 @@ static int ins_complete(int c, bool enable_pum)
         compl_col += curs_col;
         compl_length = 0;
       } else {
-        /* Search the point of change class of multibyte character
-         * or not a word single byte character backward.  */
-        if (has_mbyte) {
-          int base_class;
-          int head_off;
-
-          startcol -= (*mb_head_off)(line, line + startcol);
-          base_class = mb_get_class(line + startcol);
-          while (--startcol >= 0) {
-            head_off = (*mb_head_off)(line, line + startcol);
-            if (base_class != mb_get_class(line + startcol
-                    - head_off))
-              break;
-            startcol -= head_off;
+        // Search the point of change class of multibyte character
+        // or not a word single byte character backward.
+        startcol -= utf_head_off(line, line + startcol);
+        int base_class = mb_get_class(line + startcol);
+        while (--startcol >= 0) {
+          int head_off = utf_head_off(line, line + startcol);
+          if (base_class != mb_get_class(line + startcol - head_off)) {
+            break;
           }
-        } else
-          while (--startcol >= 0 && vim_iswordc(line[startcol]))
-            ;
+          startcol -= head_off;
+        }
         compl_col += ++startcol;
         compl_length = (int)curs_col - startcol;
         if (compl_length == 1) {
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index df4adef15f..5c02c4c4d6 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -722,9 +722,7 @@ static int command_line_execute(VimState *state, int key)
       s->j = ccline.cmdpos;
       s->i = (int)(s->xpc.xp_pattern - ccline.cmdbuff);
       while (--s->j > s->i) {
-        if (has_mbyte) {
-          s->j -= (*mb_head_off)(ccline.cmdbuff, ccline.cmdbuff + s->j);
-        }
+        s->j -= utf_head_off(ccline.cmdbuff, ccline.cmdbuff + s->j);
         if (vim_ispathsep(ccline.cmdbuff[s->j])) {
           found = true;
           break;
@@ -744,9 +742,7 @@ static int command_line_execute(VimState *state, int key)
       s->j = ccline.cmdpos - 1;
       s->i = (int)(s->xpc.xp_pattern - ccline.cmdbuff);
       while (--s->j > s->i) {
-        if (has_mbyte) {
-          s->j -= (*mb_head_off)(ccline.cmdbuff, ccline.cmdbuff + s->j);
-        }
+        s->j -= utf_head_off(ccline.cmdbuff, ccline.cmdbuff + s->j);
         if (vim_ispathsep(ccline.cmdbuff[s->j])
 #ifdef BACKSLASH_IN_FILENAME
             && vim_strchr((const char_u *)" *?[{`$%#", ccline.cmdbuff[s->j + 1])
@@ -1432,20 +1428,17 @@ static int command_line_handle_key(CommandLineState *s)
       return command_line_not_changed(s);
     }
     do {
-      --ccline.cmdpos;
-      if (has_mbyte) {                 // move to first byte of char
-        ccline.cmdpos -= (*mb_head_off)(ccline.cmdbuff,
-                                        ccline.cmdbuff + ccline.cmdpos);
-      }
+      ccline.cmdpos--;
+      // Move to first byte of possibly multibyte char.
+      ccline.cmdpos -= utf_head_off(ccline.cmdbuff,
+                                    ccline.cmdbuff + ccline.cmdpos);
       ccline.cmdspos -= cmdline_charsize(ccline.cmdpos);
     } while (ccline.cmdpos > 0
              && (s->c == K_S_LEFT || s->c == K_C_LEFT
                  || (mod_mask & (MOD_MASK_SHIFT|MOD_MASK_CTRL)))
              && ccline.cmdbuff[ccline.cmdpos - 1] != ' ');
 
-    if (has_mbyte) {
-      set_cmdspos_cursor();
-    }
+    set_cmdspos_cursor();
 
     return command_line_not_changed(s);
 
@@ -2271,14 +2264,10 @@ getexmodeline (
 
       if (c1 == BS || c1 == K_BS || c1 == DEL || c1 == K_DEL || c1 == K_KDEL) {
         if (!GA_EMPTY(&line_ga)) {
-          if (has_mbyte) {
-            p = (char_u *)line_ga.ga_data;
-            p[line_ga.ga_len] = NUL;
-            len = (*mb_head_off)(p, p + line_ga.ga_len - 1) + 1;
-            line_ga.ga_len -= len;
-          } else {
-            line_ga.ga_len--;
-          }
+          p = (char_u *)line_ga.ga_data;
+          p[line_ga.ga_len] = NUL;
+          len = utf_head_off(p, p + line_ga.ga_len - 1) + 1;
+          line_ga.ga_len -= len;
           goto redraw;
         }
         continue;
@@ -3159,18 +3148,15 @@ void put_on_cmdline(char_u *str, int len, int redraw)
     i = 0;
     c = utf_ptr2char(ccline.cmdbuff + ccline.cmdpos);
     while (ccline.cmdpos > 0 && utf_iscomposing(c)) {
-      i = (*mb_head_off)(ccline.cmdbuff,
-                         ccline.cmdbuff + ccline.cmdpos - 1) + 1;
+      i = utf_head_off(ccline.cmdbuff, ccline.cmdbuff + ccline.cmdpos - 1) + 1;
       ccline.cmdpos -= i;
       len += i;
       c = utf_ptr2char(ccline.cmdbuff + ccline.cmdpos);
     }
     if (i == 0 && ccline.cmdpos > 0 && arabic_maycombine(c)) {
-      /* Check the previous character for Arabic combining pair. */
-      i = (*mb_head_off)(ccline.cmdbuff,
-                         ccline.cmdbuff + ccline.cmdpos - 1) + 1;
-      if (arabic_combine(utf_ptr2char(ccline.cmdbuff
-                  + ccline.cmdpos - i), c)) {
+      // Check the previous character for Arabic combining pair.
+      i = utf_head_off(ccline.cmdbuff, ccline.cmdbuff + ccline.cmdpos - 1) + 1;
+      if (arabic_combine(utf_ptr2char(ccline.cmdbuff + ccline.cmdpos - i), c)) {
         ccline.cmdpos -= i;
         len += i;
       } else
diff --git a/src/nvim/getchar.c b/src/nvim/getchar.c
index b57e1f6558..0379b1cadb 100644
--- a/src/nvim/getchar.c
+++ b/src/nvim/getchar.c
@@ -2129,13 +2129,14 @@ static int vgetorpeek(int advance)
               curwin->w_wcol = curwin->w_width - 1;
               col = curwin->w_cursor.col - 1;
             }
-            if (has_mbyte && col > 0 && curwin->w_wcol > 0) {
-              /* Correct when the cursor is on the right halve
-               * of a double-wide character. */
+            if (col > 0 && curwin->w_wcol > 0) {
+              // Correct when the cursor is on the right halve
+              // of a double-wide character.
               ptr = get_cursor_line_ptr();
-              col -= (*mb_head_off)(ptr, ptr + col);
-              if ((*mb_ptr2cells)(ptr + col) > 1)
-                --curwin->w_wcol;
+              col -= utf_head_off(ptr, ptr + col);
+              if (utf_ptr2cells(ptr + col) > 1) {
+                curwin->w_wcol--;
+              }
             }
           }
           setcursor();
diff --git a/src/nvim/macros.h b/src/nvim/macros.h
index b02af723b4..d447bff765 100644
--- a/src/nvim/macros.h
+++ b/src/nvim/macros.h
@@ -118,7 +118,8 @@
 // Advance multi-byte pointer, do not skip over composing chars.
 # define MB_CPTR_ADV(p)     (p += utf_ptr2len(p))
 // Backup multi-byte pointer. Only use with "p" > "s" !
-# define MB_PTR_BACK(s, p)  (p -= mb_head_off((char_u *)s, (char_u *)p - 1) + 1)
+# define MB_PTR_BACK(s, p) \
+          (p -= utf_head_off((char_u *)s, (char_u *)p - 1) + 1)
 // get length of multi-byte char, not including composing chars
 # define MB_CPTR2LEN(p)     utf_ptr2len(p)
 
diff --git a/src/nvim/mark.c b/src/nvim/mark.c
index 3861d9ceb8..5366fa4b7f 100644
--- a/src/nvim/mark.c
+++ b/src/nvim/mark.c
@@ -1468,7 +1468,7 @@ void mark_mb_adjustpos(buf_T *buf, pos_T *lp)
     if (*p == NUL || (int)STRLEN(p) < lp->col) {
       lp->col = 0;
     } else {
-      lp->col -= (*mb_head_off)(p, p + lp->col);
+      lp->col -= utf_head_off(p, p + lp->col);
     }
     // Reset "coladd" when the cursor would be on the right half of a
     // double-wide character.
diff --git a/src/nvim/mbyte.c b/src/nvim/mbyte.c
index 94bf7fb985..11c1897153 100644
--- a/src/nvim/mbyte.c
+++ b/src/nvim/mbyte.c
@@ -1710,7 +1710,7 @@ void mb_check_adjust_col(void *win_)
         win->w_cursor.col = len - 1;
       }
       // Move the cursor to the head byte.
-      win->w_cursor.col -= (*mb_head_off)(p, p + win->w_cursor.col);
+      win->w_cursor.col -= utf_head_off(p, p + win->w_cursor.col);
     }
 
     // Reset `coladd` when the cursor would be on the right half of a
diff --git a/src/nvim/mbyte.h b/src/nvim/mbyte.h
index 5f48e1783e..6ec25edc4a 100644
--- a/src/nvim/mbyte.h
+++ b/src/nvim/mbyte.h
@@ -53,7 +53,6 @@ enum { MAX_MCO = 6 };
 #define mb_ptr2cells utf_ptr2cells
 #define mb_ptr2cells_len utf_ptr2cells_len
 #define mb_char2cells utf_char2cells
-#define mb_head_off utf_head_off
 
 /// Flags for vimconv_T
 typedef enum {
diff --git a/src/nvim/memline.c b/src/nvim/memline.c
index fbd376641f..61d944eb75 100644
--- a/src/nvim/memline.c
+++ b/src/nvim/memline.c
@@ -4035,24 +4035,18 @@ int incl(pos_T *lp)
 
 int dec(pos_T *lp)
 {
-  char_u      *p;
-
   lp->coladd = 0;
   if (lp->col > 0) {            // still within line
     lp->col--;
-    if (has_mbyte) {
-      p = ml_get(lp->lnum);
-      lp->col -= (*mb_head_off)(p, p + lp->col);
-    }
+    char_u *p = ml_get(lp->lnum);
+    lp->col -= utf_head_off(p, p + lp->col);
     return 0;
   }
   if (lp->lnum > 1) {           // there is a prior line
     lp->lnum--;
-    p = ml_get(lp->lnum);
+    char_u *p = ml_get(lp->lnum);
     lp->col = (colnr_T)STRLEN(p);
-    if (has_mbyte) {
-      lp->col -= (*mb_head_off)(p, p + lp->col);
-    }
+    lp->col -= utf_head_off(p, p + lp->col);
     return 1;
   }
   return -1;                    // at start of file
diff --git a/src/nvim/misc1.c b/src/nvim/misc1.c
index caaa310a8b..50cc9dae02 100644
--- a/src/nvim/misc1.c
+++ b/src/nvim/misc1.c
@@ -548,7 +548,7 @@ open_line (
 
           /* blank-out any other chars from the old leader. */
           while (--p >= leader) {
-            int l = mb_head_off(leader, p);
+            int l = utf_head_off(leader, p);
 
             if (l > 1) {
               p -= l;
@@ -1652,9 +1652,7 @@ int del_bytes(colnr_T count, bool fixpos_arg, bool use_delcombine)
         ) {
       --curwin->w_cursor.col;
       curwin->w_cursor.coladd = 0;
-      if (has_mbyte)
-        curwin->w_cursor.col -=
-          (*mb_head_off)(oldp, oldp + curwin->w_cursor.col);
+      curwin->w_cursor.col -= utf_head_off(oldp, oldp + curwin->w_cursor.col);
     }
     count = oldlen - col;
     movelen = 1;
diff --git a/src/nvim/normal.c b/src/nvim/normal.c
index afddd548a3..0bf93ee001 100644
--- a/src/nvim/normal.c
+++ b/src/nvim/normal.c
@@ -2858,9 +2858,10 @@ static void find_start_of_word(pos_T *pos)
 
   while (pos->col > 0) {
     col = pos->col - 1;
-    col -= (*mb_head_off)(line, line + col);
-    if (get_mouse_class(line + col) != cclass)
+    col -= utf_head_off(line, line + col);
+    if (get_mouse_class(line + col) != cclass) {
       break;
+    }
     pos->col = col;
   }
 }
@@ -2877,8 +2878,8 @@ static void find_end_of_word(pos_T *pos)
 
   line = ml_get(pos->lnum);
   if (*p_sel == 'e' && pos->col > 0) {
-    --pos->col;
-    pos->col -= (*mb_head_off)(line, line + pos->col);
+    pos->col--;
+    pos->col -= utf_head_off(line, line + pos->col);
   }
   cclass = get_mouse_class(line + pos->col);
   while (line[pos->col] != NUL) {
@@ -3094,9 +3095,9 @@ size_t find_ident_at_pos(win_T *wp, linenr_T lnum, colnr_T startcol,
     // When starting on a ']' count it, so that we include the '['.
     bn = ptr[col] == ']';
 
-    /*
-     * 2. Back up to start of identifier/string.
-     */
+    //
+    // 2. Back up to start of identifier/string.
+    //
     // Remember class of character under cursor.
     if ((find_type & FIND_EVAL) && ptr[col] == ']') {
       this_class = mb_get_class((char_u *)"a");
@@ -3129,7 +3130,7 @@ size_t find_ident_at_pos(win_T *wp, linenr_T lnum, colnr_T startcol,
   }
 
   if (ptr[col] == NUL || (i == 0 && this_class != 2)) {
-    // didn't find an identifier or string
+    // Didn't find an identifier or string.
     if (find_type & FIND_STRING) {
       EMSG(_("E348: No string under cursor"));
     } else {
diff --git a/src/nvim/ops.c b/src/nvim/ops.c
index 9ffd934d44..23948df769 100644
--- a/src/nvim/ops.c
+++ b/src/nvim/ops.c
@@ -520,12 +520,12 @@ static void block_insert(oparg_T *oap, char_u *s, int b_insert, struct block_def
       }
     }
 
-    if (has_mbyte && spaces > 0) {
+    if (spaces > 0) {
       int off;
 
       // Avoid starting halfway through a multi-byte character.
       if (b_insert) {
-        off = (*mb_head_off)(oldp, oldp + offset + spaces);
+        off = utf_head_off(oldp, oldp + offset + spaces);
       } else {
         off = (*mb_off_next)(oldp, oldp + offset);
         offset += off;
@@ -2460,11 +2460,10 @@ static void op_yank_reg(oparg_T *oap, bool message, yankreg_T *reg, bool append)
         if (virtual_op) {
           getvcol(curwin, &oap->end, &cs, NULL, &ce);
           if (p[endcol] == NUL || (cs + oap->end.coladd < ce
-                                   /* Don't add space for double-wide
-                                    * char; endcol will be on last byte
-                                    * of multi-byte char. */
-                                   && (*mb_head_off)(p, p + endcol) == 0
-                                   )) {
+                                   // Don't add space for double-wide
+                                   // char; endcol will be on last byte
+                                   // of multi-byte char.
+                                   && utf_head_off(p, p + endcol) == 0)) {
             if (oap->start.lnum == oap->end.lnum
                 && oap->start.col == oap->end.col) {
               /* Special case: inside a single char */
@@ -3021,7 +3020,7 @@ void do_put(int regname, yankreg_T *reg, int dir, long count, int flags)
         bd.startspaces = incr - bd.endspaces;
         --bd.textcol;
         delcount = 1;
-        bd.textcol -= (*mb_head_off)(oldp, oldp + bd.textcol);
+        bd.textcol -= utf_head_off(oldp, oldp + bd.textcol);
         if (oldp[bd.textcol] != TAB) {
           /* Only a Tab can be split into spaces.  Other
            * characters will have to be moved to after the
diff --git a/src/nvim/path.c b/src/nvim/path.c
index cc4a5f62a7..eeb374cf44 100644
--- a/src/nvim/path.c
+++ b/src/nvim/path.c
@@ -1819,7 +1819,7 @@ void path_fix_case(char_u *name)
 int after_pathsep(const char *b, const char *p)
 {
   return p > b && vim_ispathsep(p[-1])
-         && (!has_mbyte || (*mb_head_off)((char_u *)b, (char_u *)p - 1) == 0);
+         && utf_head_off((char_u *)b, (char_u *)p - 1) == 0;
 }
 
 /*
diff --git a/src/nvim/regexp.c b/src/nvim/regexp.c
index 98d737c9a9..bbc161ee3e 100644
--- a/src/nvim/regexp.c
+++ b/src/nvim/regexp.c
@@ -3653,8 +3653,7 @@ static long regtry(bt_regprog_T *prog, colnr_T col)
 static int reg_prev_class(void)
 {
   if (reginput > regline) {
-    return mb_get_class_tab(reginput - 1 - (*mb_head_off)(regline,
-                                                          reginput - 1),
+    return mb_get_class_tab(reginput - 1 - utf_head_off(regline, reginput - 1),
                             rex.reg_buf->b_chartab);
   }
   return -1;
diff --git a/src/nvim/regexp_nfa.c b/src/nvim/regexp_nfa.c
index 29191c14a8..3be1f3d2f3 100644
--- a/src/nvim/regexp_nfa.c
+++ b/src/nvim/regexp_nfa.c
@@ -4639,10 +4639,10 @@ static int recursive_regmatch(nfa_state_T *state, nfa_pim_T *pim, nfa_regprog_T
       }
       if ((int)(reginput - regline) >= state->val) {
         reginput -= state->val;
-        if (has_mbyte)
-          reginput -= mb_head_off(regline, reginput);
-      } else
+        reginput -= utf_head_off(regline, reginput);
+      } else {
         reginput = regline;
+      }
     }
   }
 
diff --git a/src/nvim/screen.c b/src/nvim/screen.c
index 6b75902f87..5a43f1b619 100644
--- a/src/nvim/screen.c
+++ b/src/nvim/screen.c
@@ -3435,7 +3435,7 @@ win_line (
         // Found last space before word: check for line break.
         if (wp->w_p_lbr && c0 == c && vim_isbreak(c)
             && !vim_isbreak((int)(*ptr))) {
-          int mb_off = has_mbyte ? (*mb_head_off)(line, ptr - 1) : 0;
+          int mb_off = utf_head_off(line, ptr - 1);
           char_u *p = ptr - (mb_off + 1);
           // TODO: is passing p for start of the line OK?
           n_extra = win_lbr_chartabsize(wp, line, p, (colnr_T)vcol, NULL) - 1;
diff --git a/src/nvim/search.c b/src/nvim/search.c
index 40d3f74103..9280bb6fa4 100644
--- a/src/nvim/search.c
+++ b/src/nvim/search.c
@@ -821,11 +821,10 @@ int searchit(
                         pos->lnum, FALSE));
               }
             } else {
-              --pos->col;
-              if (has_mbyte
-                  && pos->lnum <= buf->b_ml.ml_line_count) {
-                ptr = ml_get_buf(buf, pos->lnum, FALSE);
-                pos->col -= (*mb_head_off)(ptr, ptr + pos->col);
+              pos->col--;
+              if (pos->lnum <= buf->b_ml.ml_line_count) {
+                ptr = ml_get_buf(buf, pos->lnum, false);
+                pos->col -= utf_head_off(ptr, ptr + pos->col);
               }
             }
           } else {
@@ -1423,7 +1422,7 @@ int searchc(cmdarg_T *cap, int t_cmd)
         } else {
           if (col == 0)
             return FAIL;
-          col -= (*mb_head_off)(p, p + col - 1) + 1;
+          col -= utf_head_off(p, p + col - 1) + 1;
         }
         if (lastc_bytelen == 1) {
           if (p[col] == c && stop) {
@@ -1446,15 +1445,14 @@ int searchc(cmdarg_T *cap, int t_cmd)
   }
 
   if (t_cmd) {
-    /* backup to before the character (possibly double-byte) */
+    // Backup to before the character (possibly double-byte).
     col -= dir;
-    if (has_mbyte) {
-      if (dir < 0)
-        /* Landed on the search char which is lastc_bytelen long */
-        col += lastc_bytelen - 1;
-      else
-        /* To previous char, which may be multi-byte. */
-        col -= (*mb_head_off)(p, p + col);
+    if (dir < 0) {
+      // Landed on the search char which is lastc_bytelen long.
+      col += lastc_bytelen - 1;
+    } else {
+      // To previous char, which may be multi-byte.
+      col -= utf_head_off(p, p + col);
     }
   }
   curwin->w_cursor.col = col;
@@ -1476,21 +1474,21 @@ pos_T *findmatch(oparg_T *oap, int initc)
   return findmatchlimit(oap, initc, 0, 0);
 }
 
-/*
- * Return TRUE if the character before "linep[col]" equals "ch".
- * Return FALSE if "col" is zero.
- * Update "*prevcol" to the column of the previous character, unless "prevcol"
- * is NULL.
- * Handles multibyte string correctly.
- */
-static int check_prevcol(char_u *linep, int col, int ch, int *prevcol)
+// Return true if the character before "linep[col]" equals "ch".
+// Return false if "col" is zero.
+// Update "*prevcol" to the column of the previous character, unless "prevcol"
+// is NULL.
+// Handles multibyte string correctly.
+static bool check_prevcol(char_u *linep, int col, int ch, int *prevcol)
 {
-  --col;
-  if (col > 0 && has_mbyte)
-    col -= (*mb_head_off)(linep, linep + col);
-  if (prevcol)
+  col--;
+  if (col > 0) {
+    col -= utf_head_off(linep, linep + col);
+  }
+  if (prevcol) {
     *prevcol = col;
-  return (col >= 0 && linep[col] == ch) ? TRUE : FALSE;
+  }
+  return (col >= 0 && linep[col] == ch) ? true : false;
 }
 
 /*
@@ -1797,9 +1795,8 @@ pos_T *findmatchlimit(oparg_T *oap, int initc, int flags, int64_t maxtravel)
         if (lisp && comment_col != MAXCOL)
           pos.col = comment_col;
       } else {
-        --pos.col;
-        if (has_mbyte)
-          pos.col -= (*mb_head_off)(linep, linep + pos.col);
+        pos.col--;
+        pos.col -= utf_head_off(linep, linep + pos.col);
       }
     } else {                          /* forward search */
       if (linep[pos.col] == NUL
@@ -2386,8 +2383,7 @@ findpar (
     // motion inclusive.
     if ((curwin->w_cursor.col = (colnr_T)STRLEN(line)) != 0) {
       curwin->w_cursor.col--;
-      curwin->w_cursor.col -=
-        (*mb_head_off)(line, line + curwin->w_cursor.col);
+      curwin->w_cursor.col -= utf_head_off(line, line + curwin->w_cursor.col);
       *pincl = true;
     }
   } else
@@ -3694,8 +3690,8 @@ find_prev_quote(
   int n;
 
   while (col_start > 0) {
-    --col_start;
-    col_start -= (*mb_head_off)(line, line + col_start);
+    col_start--;
+    col_start -= utf_head_off(line, line + col_start);
     n = 0;
     if (escape != NULL)
       while (col_start - n > 0 && vim_strchr(escape,
diff --git a/src/nvim/spell.c b/src/nvim/spell.c
index 4acbdcc298..0ac1dd95e2 100644
--- a/src/nvim/spell.c
+++ b/src/nvim/spell.c
@@ -688,8 +688,9 @@ static void find_word(matchinf_T *mip, int mode)
     arridx = endidx[endidxcnt];
     wlen = endlen[endidxcnt];
 
-    if ((*mb_head_off)(ptr, ptr + wlen) > 0)
+    if (utf_head_off(ptr, ptr + wlen) > 0) {
       continue;             // not at first byte of character
+    }
     if (spell_iswordp(ptr + wlen, mip->mi_win)) {
       if (slang->sl_compprog == NULL && !slang->sl_nobreak)
         continue;                   // next char is a word character
diff --git a/src/nvim/syntax.c b/src/nvim/syntax.c
index 3cb998b805..332c50129e 100644
--- a/src/nvim/syntax.c
+++ b/src/nvim/syntax.c
@@ -1726,16 +1726,12 @@ static int syn_current_attr(
        */
       if (do_keywords) {
         line = syn_getcurline();
-        if (vim_iswordp_buf(line + current_col, syn_buf)
-            && (current_col == 0
-                || !vim_iswordp_buf(line + current_col - 1
-                    - (has_mbyte
-                       ? (*mb_head_off)(line, line + current_col - 1)
-                       : 0)
-                    , syn_buf))) {
-          syn_id = check_keyword_id(line, (int)current_col,
-              &endcol, &flags, &next_list, cur_si,
-              &cchar);
+        const char_u *cur_pos = line + current_col;
+        if (vim_iswordp_buf(cur_pos, syn_buf)
+            && (current_col == 0 || !vim_iswordp_buf(
+                cur_pos - 1 - utf_head_off(line, cur_pos - 1), syn_buf))) {
+          syn_id = check_keyword_id(line, (int)current_col, &endcol, &flags,
+                                    &next_list, cur_si, &cchar);
           if (syn_id != 0) {
             push_current_state(KEYWORD_IDX);
             {
diff --git a/src/nvim/window.c b/src/nvim/window.c
index 3f66568b58..055564c1e0 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -5162,13 +5162,14 @@ file_name_in_line (
    * Go one char back to ":" before "//" even when ':' is not in 'isfname'.
    */
   while (ptr > line) {
-    if (has_mbyte && (len = (size_t)((*mb_head_off)(line, ptr - 1))) > 0)
+    if ((len = (size_t)(utf_head_off(line, ptr - 1))) > 0) {
       ptr -= len + 1;
-    else if (vim_isfilec(ptr[-1])
-             || ((options & FNAME_HYP) && path_is_url((char *)ptr - 1)))
-      --ptr;
-    else
+    } else if (vim_isfilec(ptr[-1])
+               || ((options & FNAME_HYP) && path_is_url((char *)ptr - 1))) {
+      ptr--;
+    } else {
       break;
+    }
   }
 
   /*