As a maintainer of archivers/par2cmdline-tbb, could you have a look at PR #252648:
In short, TBB version 2021 will soon be available as devel/onetbb but the port you maintain does not build correctly with it, see the following Poudriere run:
and error logs:
c++ -DHAVE_CONFIG_H -I. -I/usr/local/include -Wall -I/usr/local/include -O2 -pipe -fstack-protector-strong -fno-strict-aliasing -MT par2cmdline.o -MD -MP -MF .deps/par2cmdline.Tpo -c -o par2cmdline.o par2cmdline.cpp
In file included from par2cmdline.cpp:26:
./par2cmdline.h:458:12: fatal error: 'tbb/task_scheduler_init.h' file not found
1 error generated.
*** Error code 1
Could you try to provide a patch (important: *by replying to this PR*) to facilitate the migration to devel/onetbb ?
To help you modifying your port, expected patches to devel/tbb and devel/onetbb are available in PR #252648.
Thanks for your contribution,
Reply to myself: I will mark this one as deprecated. archivers/par2cmdline can be used instead.