Nightly build segfaults

[...]

With the tarball I get a popup telling me

?R.framework? cannot be opened because the developer cannot be verified.

Interesting. I am on 12.0.1 and there is no popup, but there is a
crash report with

Exception Type:        EXC_BAD_ACCESS (SIGKILL (Code Signature Invalid))

Possibly the popup was added in 12.1 beta.

[...]

The .pkg I tried is unsigned/not notarized so cannot be installed, not
even with 'Open With'.  But packages are at least sometimes signed.

FWIW I did some local builds on a Big Sur machine with Xcode 12.x with
the same settings as the CRAN builds (for readline support primarily),
and those (https://files.r-hub.io/macos/readline/) work fine on
Monterey as well.

Gabor

[...]