hash.c: +(-1) is a wrong idea

Before this changeset RHASH_ARRAY_SIZE_DEC() was expaneded to include
an expression like `RHASH_ARRAY_SIZE+(-1)`.  RHASH_ARRAY_SIZE is by
definition unsigned int.  -1 is signed, of course.  Adding a signed
and an unsigned value requires the "usual arithmetic conversions" (cf:
ISO/IEC 9899:1990 section 6.2.1.5).  -1 is converted to 0xFFFF by that.

This patch prevents that conversion.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65632 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

Author: shyouhei

hash.c

@@ -522,7 +522,11 @@ hash_array_set(VALUE hash, struct li_table *li)
 } while (0)
 
 #define RHASH_ARRAY_SIZE_INC(h) HASH_ARRAY_SIZE_ADD(h, 1)
-#define RHASH_ARRAY_SIZE_DEC(h) HASH_ARRAY_SIZE_ADD(h, -1)
+#define RHASH_ARRAY_SIZE_DEC(h) do  { \
+    HASH_ASSERT(RHASH_ARRAY_P(h)); \
+    RHASH_ARRAY_SIZE_SET((h), RHASH_ARRAY_SIZE(h) - 1); \
+    hash_verify(h); \
+} while (0)
 
 #define RHASH_CLEAR_BITS(h) do { \
     RBASIC(h)->flags &= ~RHASH_ARRAY_SIZE_MASK; \