Active Admin gem ffi won't compile on MacOS - ruby-on-rails

Question

I'm trying to run bundle install on my rails 6 app, but I can't successfully compile ffi:
../rescue [manual_assignment|✚15…3] ❯❯❯ bundle install
Fetching https://github.com/rspec/rspec-core
Fetching https://github.com/rspec/rspec-expectations
Fetching https://github.com/rspec/rspec-mocks
Fetching https://github.com/rspec/rspec-rails
Fetching https://github.com/rspec/rspec-support
The dependency tzinfo-data (>= 0) will be unused by any of the platforms Bundler is installing for. Bundler is installing for ruby but the dependency is only for x86-mingw32, x86-mswin32, x64-mingw32, java. To add those platforms to the bundle, run `bundle lock --add-platform x86-mingw32 x86-mswin32 x64-mingw32 java`.
Fetching gem metadata from https://rubygems.org/...........
Fetching gem metadata from https://rubygems.org/.
Resolving dependencies.......
Using rake 13.0.1
Using concurrent-ruby 1.1.7
Using i18n 1.8.5
Using minitest 5.14.2
Using thread_safe 0.3.6
Using tzinfo 1.2.7
Using zeitwerk 2.4.0
Using activesupport 6.0.3.2
Using builder 3.2.4
Using erubi 1.9.0
Using mini_portile2 2.4.0
Using nokogiri 1.10.10
Using rails-dom-testing 2.0.3
Using crass 1.0.6
Using loofah 2.7.0
Using rails-html-sanitizer 1.3.0
Using actionview 6.0.3.2
Using rack 2.2.3
Using rack-test 1.1.0
Using actionpack 6.0.3.2
Using nio4r 2.5.2
Using websocket-extensions 0.1.5
Using websocket-driver 0.7.3
Using actioncable 6.0.3.2
Using globalid 0.4.2
Using activejob 6.0.3.2
Using activemodel 6.0.3.2
Using activerecord 6.0.3.2
Using mimemagic 0.3.5
Using marcel 0.3.3
Using activestorage 6.0.3.2
Using mini_mime 1.0.2
Using mail 2.7.1
Using actionmailbox 6.0.3.2
Using actionmailer 6.0.3.2
Using actiontext 6.0.3.2
Fetching ruby2_keywords 0.0.2
Installing ruby2_keywords 0.0.2
Fetching arbre 1.3.0
Installing arbre 1.3.0
Using formtastic 3.1.5
Using formtastic_i18n 0.6.0
Using has_scope 0.7.2
Using method_source 1.0.0
Using thor 1.0.1
Using railties 6.0.3.2
Using responders 3.0.1
Using inherited_resources 1.11.0
Using jquery-rails 4.4.0
Using kaminari-core 1.2.1
Using kaminari-actionview 1.2.1
Using kaminari-activerecord 1.2.1
Using kaminari 1.2.1
Using polyamorous 2.3.2
Using ransack 2.3.2
Fetching ffi 1.13.1
Installing ffi 1.13.1 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
current directory: /Users/jason/.rvm/gems/ruby-2.6.3/gems/ffi-1.13.1/ext/ffi_c
/Users/jason/.rvm/rubies/ruby-2.6.3/bin/ruby -I /Users/jason/.rvm/rubies/ruby-2.6.3/lib/ruby/site_ruby/2.6.0 -r
./siteconf20200906-62332-1vq6nbs.rb extconf.rb
checking for ffi_prep_closure_loc() in -lffi... yes
checking for ffi_prep_cif_var()... yes
checking for ffi_raw_call()... yes
checking for ffi_prep_raw_closure()... yes
creating extconf.h
creating Makefile
current directory: /Users/jason/.rvm/gems/ruby-2.6.3/gems/ffi-1.13.1/ext/ffi_c
make "DESTDIR=" clean
current directory: /Users/jason/.rvm/gems/ruby-2.6.3/gems/ffi-1.13.1/ext/ffi_c
make "DESTDIR="
compiling AbstractMemory.c
compiling ArrayType.c
compiling Buffer.c
compiling Call.c
compiling ClosurePool.c
compiling DynamicLibrary.c
compiling Function.c
Function.c:852:17: error: implicit declaration of function 'ffi_prep_closure_loc' is invalid in C99
[-Werror,-Wimplicit-function-declaration]
ffiStatus = ffi_prep_closure_loc(code, &fnInfo->ffi_cif, callback_invoke, closure, code);
^
Function.c:852:17: note: did you mean 'ffi_prep_closure'?
/Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/usr/include/ffi/ffi.h:269:1: note: 'ffi_prep_closure' declared here
ffi_prep_closure(
^
1 error generated.
make: *** [Function.o] Error 1
make failed, exit code 2
Gem files will remain installed in /Users/jason/.rvm/gems/ruby-2.6.3/gems/ffi-1.13.1 for inspection.
Results logged to /Users/jason/.rvm/gems/ruby-2.6.3/extensions/x86_64-darwin-19/2.6.0/ffi-1.13.1/gem_make.out
An error occurred while installing ffi (1.13.1), and Bundler cannot continue.
Make sure that `gem install ffi -v '1.13.1' --source 'https://rubygems.org/'` succeeds before bundling.
Not sure what the ffi gem does or why I need it, but ActiveAdmin wants it:
In Gemfile:
activeadmin was resolved to 2.8.0, which depends on
sassc-rails was resolved to 2.1.2, which depends on
sassc was resolved to 2.4.0, which depends on
ffi
Any ideas why this is breaking? Thanks to everyone for any help!

Answer 1

Solved by following the steps at https://stackoverflow.com/a/48312139/13217139 then re-installed the gem with gem install ffi -- --enable-system-libffi