Upgrading to Elixir 1.12 and OTP 24 with ASDF

Erlang OTP 24 includes the long awaited JIT compiler, which makes it a must have. Elixir 1.12 can take advantage of it.

Here's a quick guide for anyone who got stuck on the upgrade using ASDF on MacOS!

There's a bug related to kerl settings in the installer that causes a cryptic error like the following for MacOS users:

checking for OpenSSL header in /usr/local/opt/openssl@1.1... yes
checking for OpenSSL in /usr/local/opt/openssl@1.1... configure: error: neither static nor dynamic crypto library found in /usr/local/opt/openssl@1.1
ERROR: /Users/username/.asdf/plugins/erlang/kerl-home/builds/asdf_24.0/otp_src_24.0/lib/crypto/configure failed!

The fix

The good news is that it only takes a single change to fix it. The file to edit is:

~/.asdf/plugins/erlang/kerl

Do a text search for "We need to" to find the following section:

_flags() {
    # We need to munge the LD and DED flags for clang 9/10 shipped with
    # High Sierra (macOS 10.13) and Mojave (macOS 10.14) and quite
    # probably for Catalina (macOS 10.15)
    case "$KERL_SYSTEM" in
        Darwin)
            osver=$(uname -r)
            case "$osver" in
                # TODO: Remove this in a future kerl release, probably
                # after Catalina (10.15)

And make the following change:

    case "$KERL_SYSTEM" in
        Darwin-disabled)
            osver=$(uname -r)

Then you can run asdf install erlang 24.0.01 and all will install as usual.