Arch Linux

botan currently depends on asio, but it's not actually used.

The only usage of asio is done using boost::asio, see https://paste.swordarmor.fr/J6mf

Also, this part of botan is not even enabled by default, as shown in the configure step:

INFO: Skipping, requires external dependency - boost bzip2 lzma openssl sqlite3 tpm zlib

So, removing the asio dependency does not make any change to the final package (verified with diffoscope on the binary package).

Additionally, if the botan feature that uses boost::asio is desired, adding boost as makedepends and boost-libs as dependency is enough, asio is not necessary (verified by building in a clean chroot).