The variable len isn't used anywhere.

src/string.c

@@ -2056,7 +2056,6 @@ mrb_cstr_to_inum(mrb_state *mrb, const char *str, int base, int badcheck)
   char *end;
   char sign = 1;
   int c;
-  long len;
   unsigned long val;
 
 #undef ISDIGIT
@@ -2113,30 +2112,25 @@ mrb_cstr_to_inum(mrb_state *mrb, const char *str, int base, int badcheck)
   }
   switch (base) {
     case 2:
-      len = 1;
       if (str[0] == '0' && (str[1] == 'b'||str[1] == 'B')) {
         str += 2;
       }
       break;
     case 3:
-      len = 2;
       break;
     case 8:
       if (str[0] == '0' && (str[1] == 'o'||str[1] == 'O')) {
         str += 2;
       }
     case 4: case 5: case 6: case 7:
-      len = 3;
       break;
     case 10:
       if (str[0] == '0' && (str[1] == 'd'||str[1] == 'D')) {
         str += 2;
       }
     case 9: case 11: case 12: case 13: case 14: case 15:
-      len = 4;
       break;
     case 16:
-      len = 4;
       if (str[0] == '0' && (str[1] == 'x'||str[1] == 'X')) {
         str += 2;
       }
@@ -2145,12 +2139,6 @@ mrb_cstr_to_inum(mrb_state *mrb, const char *str, int base, int badcheck)
       if (base < 2 || 36 < base) {
         mrb_raisef(mrb, E_ARGUMENT_ERROR, "illegal radix %d", base);
       }
-      if (base <= 32) {
-        len = 5;
-      }
-      else {
-        len = 6;
-      }
       break;
   } /* end of switch (base) { */
   if (*str == '0') {    /* squeeze preceeding 0s */
@@ -2171,7 +2159,6 @@ mrb_cstr_to_inum(mrb_state *mrb, const char *str, int base, int badcheck)
     if (badcheck) goto bad;
     return mrb_fixnum_value(0);
   }
-  len *= strlen(str);
 
   val = strtoul((char*)str, &end, base);