redefine POST/NEG FIXABLE using INT_MIN/MAX

include/mruby/numeric.h

@@ -10,10 +10,8 @@
 #include <limits.h>
 
 #define RSHIFT(x,y) ((x)>>(int)(y))
-#define FIXNUM_MAX (LONG_MAX>>1)
-#define FIXNUM_MIN RSHIFT((long)LONG_MIN,1)
-#define POSFIXABLE(f) ((f) < FIXNUM_MAX+1)
-#define NEGFIXABLE(f) ((f) >= FIXNUM_MIN)
+#define POSFIXABLE(f) ((f) <= INT_MAX)
+#define NEGFIXABLE(f) ((f) >= INT_MIN)
 #define FIXABLE(f) (POSFIXABLE(f) && NEGFIXABLE(f))
 
 mrb_value mrb_flt2big(mrb_state *mrb, mrb_float d);

src/object.c

@@ -565,8 +565,7 @@ mrb_convert_to_integer(mrb_state *mrb, mrb_value val, int base)
   switch (mrb_type(val)) {
     case MRB_TT_FLOAT:
       if (base != 0) goto arg_error;
-      if (mrb_float(val) <= (double)FIXNUM_MAX
-          && mrb_float(val) >= (double)FIXNUM_MIN) {
+      if (FIXABLE(mrb_float(val))) {
           break;
       }
       return mrb_flt2big(mrb, mrb_float(val));