This blog is updated daily.
A general description is here.
Startup banners and ‘R --version’ no longer report ‘(64-bit)’ as this is almost universal - the increasingly rare 32-bit platforms will still report ‘(32-bit)’.
On Windows, ditto for window titles.
Serializations can now be interrupted (e.g., by ‘Ctrl-C’ on a Unix-alike) if they take too long, as e.g., from ‘save.image()’, thanks to suggestions by Ivan Krylov and others on R-devel.
‘configure’ will warn if it encounters a 32-bit build, as that is nowadays almost untested.
‘tools::Rdiff()’ is now more robust against invalid strings, fixing installation tests on Windows without Rtools installed (PR#18530).