merge revision(s) 8c360ce713f57d4177de833297364f6f6d950420: [Backport #19589]

hash.c: Fix hash_iter_lev_dec corrupting shape

	[Bug #19589]

	When decrementing `iter_lev` from `65` to `64` the flags would be
	corrupted, causing the shape_id to be invalid.
	---
	 hash.c                 | 12 +++++++++---
	 test/ruby/test_hash.rb | 11 +++++++++++
	 2 files changed, 20 insertions(+), 3 deletions(-)

hash.c

@@ -1409,13 +1409,19 @@ iter_lev_in_ivar_set(VALUE hash, int lev)
     rb_ivar_set_internal(hash, id_hash_iter_lev, INT2FIX(lev));
 }
 
-static int
+static inline int
 iter_lev_in_flags(VALUE hash)
 {
     unsigned int u = (unsigned int)((RBASIC(hash)->flags >> RHASH_LEV_SHIFT) & RHASH_LEV_MAX);
     return (int)u;
 }
 
+static inline void
+iter_lev_in_flags_set(VALUE hash, int lev)
+{
+    RBASIC(hash)->flags = ((RBASIC(hash)->flags & ~RHASH_LEV_MASK) | ((VALUE)lev << RHASH_LEV_SHIFT));
+}
+
 static int
 RHASH_ITER_LEV(VALUE hash)
 {
@@ -1439,7 +1445,7 @@ hash_iter_lev_inc(VALUE hash)
     }
     else {
         lev += 1;
-        RBASIC(hash)->flags = ((RBASIC(hash)->flags & ~RHASH_LEV_MASK) | ((VALUE)lev << RHASH_LEV_SHIFT));
+        iter_lev_in_flags_set(hash, lev);
         if (lev == RHASH_LEV_MAX) {
             iter_lev_in_ivar_set(hash, lev);
         }
@@ -1457,7 +1463,7 @@ hash_iter_lev_dec(VALUE hash)
     }
     else {
         HASH_ASSERT(lev > 0);
-        RBASIC(hash)->flags = ((RBASIC(hash)->flags & ~RHASH_LEV_MASK) | ((lev-1) << RHASH_LEV_SHIFT));
+        iter_lev_in_flags_set(hash, lev - 1);
     }
 }
 

test/ruby/test_hash.rb

@@ -1556,6 +1556,17 @@ class TestHash < Test::Unit::TestCase
     end
   end
 
+  def hash_iter_recursion(h, level)
+    return if level == 0
+    h.each_key {}
+    h.each_value { hash_iter_recursion(h, level - 1) }
+  end
+
+  def test_iterlevel_in_ivar_bug19589
+    h = { a: nil }
+    hash_iter_recursion(h, 200)
+  end
+
   def test_threaded_iter_level
     bug9105 = '[ruby-dev:47807] [Bug #9105]'
     h = @cls[1=>2]

version.h

@@ -11,7 +11,7 @@
 # define RUBY_VERSION_MINOR RUBY_API_VERSION_MINOR
 #define RUBY_VERSION_TEENY 2
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 86
+#define RUBY_PATCHLEVEL 87
 
 #include "ruby/version.h"
 #include "ruby/internal/abi.h"