I tried to build the intmap-lazt-properties component of the containers package using the new support for building individual components. It fails with this message:
$ cabal build test:intmap-lazy-properties
Configuring with default flags. If this fails, please run configure manually.
cabal: Cannot build the test suite 'intmap-lazy-properties' because test
suites are not enabled. Run configure with the flag --enable-tests
It seems like we need to reconfigure with --enable-test automatically.
The same most likely goes for benchmarks.
This has been fixed for ages.