merge revision(s) 31e0382723bfb35cffe3ca485dd0577668cafa07,5e5fb72f99701dc27c66ab148471893f14e6d6f0,fb6ebe55d91187d9635e0183d47dbf38e95b1141,522d4cd32f7727886f4fcbc28ed29c08d361ee20: [Backport #17735]

	Keep non evaluated keys in `Hash#transform_keys!` [Bug #17735]

	---
	 hash.c                                     |  6 +++++-
	 spec/ruby/core/hash/transform_keys_spec.rb | 12 +++++++++++-
	 test/ruby/test_hash.rb                     |  8 ++++++++
	 3 files changed, 24 insertions(+), 2 deletions(-)

	Clear an intermediate hash [Bug #17735]

	---
	 hash.c | 1 +
	 1 file changed, 1 insertion(+)

	Hide an intermediate array

	---
	 hash.c | 6 ++++--
	 1 file changed, 4 insertions(+), 2 deletions(-)

	Force recycle intermediate collection in Hash#transform_keys! [Bug
	 #17735]

	* Force recycle intermediate hash

	* Force recycle intermediate array too

	https://github.com/ruby/ruby/pull/4329#issuecomment-808840718
	---
	 hash.c | 2 ++
	 1 file changed, 2 insertions(+)

1 files changed, 1 insertions, 1 deletions

diff --git a/version.h b/version.h
index 41f7a51c79..899059b708 100644
--- a/version.h
+++ b/version.h
@@ -12,7 +12,7 @@
 # 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 66
+#define RUBY_PATCHLEVEL 67
 
 #define RUBY_RELEASE_YEAR 2021
 #define RUBY_RELEASE_MONTH 4