Changed the behavior of mrb_range_beg_len(); close #3411

The new API is:

int mrb_range_beg_len(mrb, range, &beg, &len, len, trunc)

The new argument `trunc` is a boolean value that specifies
whether the function truncates the range. The new return value
is an integer instead of a boolean, that is:

 0: not a range
 1: range with proper edges
 2: out of range

To get the old behavior, you have to rewrite:

  mrb_range_beg_len(mrb, range, &beg, &len, len)

to:

  mrn_range_beg_len(mrb, range, &beg, &len, len, TRUE) == 1

[Breaking Change]

1 files changed, 7 insertions, 1 deletions

diff --git a/mrbgems/mruby-string-ext/src/string.c b/mrbgems/mruby-string-ext/src/string.c
index c6a9e1d0b..7e87b3db4 100644
--- a/mrbgems/mruby-string-ext/src/string.c
+++ b/mrbgems/mruby-string-ext/src/string.c
@@ -56,8 +56,14 @@ mrb_str_byteslice(mrb_state *mrb, mrb_value str)
       mrb_int beg;
 
       len = RSTRING_LEN(str);
-      if (mrb_range_beg_len(mrb, a1, &beg, &len, len)) {
+      switch (mrb_range_beg_len(mrb, a1, &beg, &len, len, TRUE)) {
+      case 0:                   /* not range */
+        break;
+      case 1:                   /* range */
         return mrb_str_substr(mrb, str, beg, len);
+      case 2:                   /* out of range */
+        mrb_raisef(mrb, E_RANGE_ERROR, "%S out of range", a1);
+        break;
       }
       return mrb_nil_value();
     }