Ruby

[DOC] Tweak an example in language/box.md

Although the example code comments indicate that it returns false,
a non-matching result for =~ is actually nil.

Foo.foo.blank? #=> false
"foo".blank?   #=> false

https://github.com/ruby/ruby/blob/v4.0.0-preview3/doc/language/box.md?plain=1#L115-L122...

[DOC] Use Ruby::Box#require_relative in box.md examples

Based on the example, it appears that foo.rb and main.rb are expected to be in the same directory.
Since Ruby 1.9, the current directory is not included in $LOAD_PATH by default.
As a result, running box.require('foo') as shown in the sample code raises a LoadError:...

[ruby/mmtk] Process obj_free candidates in parallel

Redos commit 544770d which seems to have accidentally been undone in b27d935.

Also output GC thread backtrace in rb_mmtk_gc_thread_bug

Add rb_gc_print_backtrace

Drop memberless Data/Struct#inspect trailing space

Anonymous memberless Structs and Data were returning #<struct > and
#<data > with a trailing space. Now they return #<struct> and
#<data> to match attrless class behavior and look a bit more compact.

[ruby/json] Directly write to the output buffer when converting UTF32 to UTF8.

https://github.com/ruby/json/commit/a51317c949

[Bug #21819] Data objects without members should also be frozen

Test net-imap with ruby/net-imap#593

Delete test/net/imap/test_data_lite.rb, because the target of this
test file has been deleted by ruby/net-imap#543.

[ruby/mmtk] Use rb_mmtk_gc_thread_bug for rb_mmtk_call_object_closure

https://github.com/ruby/mmtk/commit/308936296a