From 367fdd1aee07bd856612e9d796f301e1f1d5a30b Mon Sep 17 00:00:00 2001
From: ko1 <ko1@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Thu, 17 Jan 2019 07:52:47 +0000
Subject: reset bound if the size is 0.

* hash.c (RHASH_AR_TABLE_SIZE_DEC): generally, we need to check all
  entries to calculate exact "bound" in ar_table, but if size == 0,
  we can clear bound because there are no active entries.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66843 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 hash.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/hash.c b/hash.c
index dd94ffd4a5..3dd2777cd1 100644
--- a/hash.c
+++ b/hash.c
@@ -554,11 +554,21 @@ hash_ar_table_set(VALUE hash, ar_table *ar)
 } while (0)
 
 #define RHASH_AR_TABLE_SIZE_INC(h) HASH_AR_TABLE_SIZE_ADD(h, 1)
-#define RHASH_AR_TABLE_SIZE_DEC(h) do  { \
-    HASH_ASSERT(RHASH_AR_TABLE_P(h)); \
-    RHASH_AR_TABLE_SIZE_SET((h), RHASH_AR_TABLE_SIZE(h) - 1); \
-    hash_verify(h); \
-} while (0)
+
+static inline void
+RHASH_AR_TABLE_SIZE_DEC(VALUE h) {
+    HASH_ASSERT(RHASH_AR_TABLE_P(h));
+    int new_size = RHASH_AR_TABLE_SIZE(h) - 1;
+
+    if (new_size != 0) {
+        RHASH_AR_TABLE_SIZE_SET(h, new_size);
+    }
+    else {
+        RHASH_AR_TABLE_SIZE_SET(h, 0);
+        RHASH_AR_TABLE_BOUND_SET(h, 0);
+    }
+    hash_verify(h);
+}
 
 #define RHASH_AR_TABLE_CLEAR(h) do { \
     RBASIC(h)->flags &= ~RHASH_AR_TABLE_SIZE_MASK; \
-- 
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