Perhaps this should be a proposal the Rebar3 itself, but here goes.
The BEAM comes with a number of types and flavours as specified here, which can be can passed to erl with the -emu_type and -emu_flavor flags respectively, or directly as with asan. How do you specify this with Rebar3? Taking the example of running rebar3 ct, so far what I have been doing is:
$ERL_TOP/bin/cerl -asan -- ~/.asdf/installs/rebar/3.25.0/bin/rebar3 ct
Erlang/OTP 29 [DEVELOPMENT] [erts-16.0.2] [source] [64-bit] [smp:12:12] [ds:12:12:10] [async-threads:1] [jit:ns] [address-sanitizer]
Eshell V16.0.2 (press Ctrl+G to abort, type help(). for help)
1> escript:start().
This involves building OTP from source and using that (potentially incompatible build) with Rebar3, so I’m unsure whether such a proposal would be accepted. However changing emulator types and passing other flags such as -gdbr, asan, -valgrind or -rr is very important for test and debugging NIFs (see here). Rebar3 really starts becoming a crutch in the debug process, especially when it comes to starting a shell with the project and deps loaded.