From df5ae0a55005f7f02adbf21790300f28dc2e12fc Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Tue, 27 Jun 2023 22:39:15 +0900
Subject: [PATCH] Use `rb_reg_nth_defined` instead of `rb_match_nth_defined`

---
 include/ruby/internal/intern/re.h |  5 -----
 internal/re.h                     |  1 -
 re.c                              | 17 -----------------
 variable.c                        |  2 +-
 4 files changed, 1 insertion(+), 24 deletions(-)

diff --git a/include/ruby/internal/intern/re.h b/include/ruby/internal/intern/re.h
index 31f5593275..4dd58b469b 100644
--- a/include/ruby/internal/intern/re.h
+++ b/include/ruby/internal/intern/re.h
@@ -87,11 +87,6 @@ void rb_match_busy(VALUE md);
  * @retval     RUBY_Qfalse    There is a `n`-th capture and is empty.
  * @retval     RUBY_Qtrue     There is a `n`-th capture that has something.
  *
- * @internal
- *
- * @shyouhei   wonders:  why   there   are   both  rb_reg_match_defined()   and
- * rb_match_nth_defined, which  are largely the  same things, but do  not share
- * their implementations at all?
  */
 VALUE rb_reg_nth_defined(int n, VALUE md);
 
diff --git a/internal/re.h b/internal/re.h
index 7b2505b9a8..f85ec09ab3 100644
--- a/internal/re.h
+++ b/internal/re.h
@@ -22,7 +22,6 @@ VALUE rb_reg_equal(VALUE re1, VALUE re2);
 void rb_backref_set_string(VALUE string, long pos, long len);
 void rb_match_unbusy(VALUE);
 int rb_match_count(VALUE match);
-int rb_match_nth_defined(int nth, VALUE match);
 VALUE rb_reg_new_ary(VALUE ary, int options);
 
 #endif /* INTERNAL_RE_H */
diff --git a/re.c b/re.c
index f8db6cb82d..4728fca654 100644
--- a/re.c
+++ b/re.c
@@ -1450,23 +1450,6 @@ rb_match_count(VALUE match)
     return regs->num_regs;
 }
 
-int
-rb_match_nth_defined(int nth, VALUE match)
-{
-    struct re_registers *regs;
-    if (NIL_P(match)) return FALSE;
-    regs = RMATCH_REGS(match);
-    if (!regs) return FALSE;
-    if (nth >= regs->num_regs) {
-        return FALSE;
-    }
-    if (nth < 0) {
-        nth += regs->num_regs;
-        if (nth <= 0) return FALSE;
-    }
-    return (BEG(nth) != -1);
-}
-
 static void
 match_set_string(VALUE m, VALUE string, long pos, long len)
 {
diff --git a/variable.c b/variable.c
index e9735a8c4d..c6c70e1391 100644
--- a/variable.c
+++ b/variable.c
@@ -902,7 +902,7 @@ rb_f_global_variables(void)
         int i, nmatch = rb_match_count(backref);
         buf[0] = '$';
         for (i = 1; i <= nmatch; ++i) {
-            if (!rb_match_nth_defined(i, backref)) continue;
+            if (!RTEST(rb_reg_nth_defined(i, backref))) continue;
             if (i < 10) {
                 /* probably reused, make static ID */
                 buf[1] = (char)(i + '0');