merge revision(s) 56ecc243e230e8e99761ec0ffc5116601f094bb0: [Backport #20868]

	[Bug #20868] Fix Method#hash to not change after compaction

	The hash value of a Method must remain constant after a compaction, otherwise
	it may not work as the key in a hash table.

	For example:

	    def a; end

	    # Need this method here because otherwise the iseq may be on the C stack
	    # which would get pinned and not move during compaction
	    def get_hash
	      method(:a).hash
	    end

	    puts get_hash # => 2993401401091578131

	    GC.verify_compaction_references(expand_heap: true, toward: :empty)

	    puts get_hash # => -2162775864511574135

3 files changed, 23 insertions, 2 deletions

diff --git a/test/ruby/test_method.rb b/test/ruby/test_method.rb
index a04666890e..aa564cde25 100644
--- a/test/ruby/test_method.rb
+++ b/test/ruby/test_method.rb
@@ -209,6 +209,27 @@ class TestMethod < Test::Unit::TestCase
     assert_kind_of(String, o.method(:foo).hash.to_s)
   end
 
+  def test_hash_does_not_change_after_compaction
+    omit "compaction is not supported on this platform" unless GC.respond_to?(:compact)
+
+    # iseq backed method
+    assert_separately([], <<~RUBY)
+      def a; end
+
+      # Need this method here because otherwise the iseq may be on the C stack
+      # which would get pinned and not move during compaction
+      def get_hash
+        method(:a).hash
+      end
+
+      hash = get_hash
+
+      GC.verify_compaction_references(expand_heap: true, toward: :empty)
+
+      assert_equal(hash, get_hash)
+    RUBY
+  end
+
   def test_owner
     c = Class.new do
       def foo; end
diff --git a/version.h b/version.h
index 27acd894cf..a82aed30ce 100644
--- a/version.h
+++ b/version.h
@@ -11,7 +11,7 @@
 # define RUBY_VERSION_MINOR RUBY_API_VERSION_MINOR
 #define RUBY_VERSION_TEENY 6
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 235
+#define RUBY_PATCHLEVEL 236
 
 #include "ruby/version.h"
 #include "ruby/internal/abi.h"
diff --git a/vm_method.c b/vm_method.c
index 17aeb16a66..7b9deffe1e 100644
--- a/vm_method.c
+++ b/vm_method.c
@@ -2105,7 +2105,7 @@ rb_hash_method_definition(st_index_t hash, const rb_method_definition_t *def)
 
     switch (def->type) {
       case VM_METHOD_TYPE_ISEQ:
-        return rb_hash_uint(hash, (st_index_t)def->body.iseq.iseqptr);
+        return rb_hash_uint(hash, (st_index_t)def->body.iseq.iseqptr->body);
       case VM_METHOD_TYPE_CFUNC:
         hash = rb_hash_uint(hash, (st_index_t)def->body.cfunc.func);
         return rb_hash_uint(hash, def->body.cfunc.argc);