Protobuf can't be required on Ruby 2.6

[tenderlove]

What version of protobuf and what language are you using?
Version: v3.6.1
Language: Ruby

What operating system (Linux, Windows, ...) and version?

[aaron@TC ~]$ uname -a
Darwin TC.local 17.7.0 Darwin Kernel Version 17.7.0: Fri Jul  6 19:54:51 PDT 2018; root:xnu-4570.71.3~2/RELEASE_X86_64 x86_64

What runtime / compiler are you using (e.g., python version or gcc version)

[aaron@TC ~]$ ruby -v
ruby 2.6.0dev (2018-06-21 gc-compact-7-27 63710) [x86_64-darwin17]
last_commit=Yay!  We did more work!!!
[aaron@TC ~]$ 

What did you do?
Steps to reproduce the behavior:

1. Install Ruby 2.6 from source
2. Install google-protobuf gem
3. Require protobuf
4. See error when requiring the gem

What did you expect to see

The gem can be required

What did you see instead?

An error indicating the gem cannot be required. Here is the output on my terminal:

[aaron@TC ~]$ gem install google-protobuf
Successfully installed google-protobuf-3.6.1-universal-darwin
Parsing documentation for google-protobuf-3.6.1-universal-darwin
Done installing documentation for google-protobuf after 0 seconds
1 gem installed
[aaron@TC ~]$ ruby -r google/protobuf -e'puts "hello"'
Traceback (most recent call last):
	6: from /Users/aaron/.rbenv/versions/ruby-trunk/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:34:in `require'
	5: from /Users/aaron/.rbenv/versions/ruby-trunk/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:130:in `rescue in require'
	4: from /Users/aaron/.rbenv/versions/ruby-trunk/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:130:in `require'
	3: from /Users/aaron/.rbenv/versions/ruby-trunk/lib/ruby/gems/2.6.0/gems/google-protobuf-3.6.1-universal-darwin/lib/google/protobuf.rb:47:in `<top (required)>'
	2: from /Users/aaron/.rbenv/versions/ruby-trunk/lib/ruby/gems/2.6.0/gems/google-protobuf-3.6.1-universal-darwin/lib/google/protobuf.rb:50:in `rescue in <top (required)>'
	1: from /Users/aaron/.rbenv/versions/ruby-trunk/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
/Users/aaron/.rbenv/versions/ruby-trunk/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require': cannot load such file -- google/protobuf_c (LoadError)

Anything else we should know about your project / environment

I am working against a development version of Ruby.

Thanks!

[tenderlove]

I was able to get this to work by manually specifying the platform is ruby:

[aaron@TC ~]$ gem install google-protobuf --platform=ruby
Fetching: google-protobuf-3.6.1.gem (100%)
Building native extensions. This could take a while...
Successfully installed google-protobuf-3.6.1
Parsing documentation for google-protobuf-3.6.1
Installing ri documentation for google-protobuf-3.6.1
Done installing documentation for google-protobuf after 3 seconds
1 gem installed
[aaron@TC ~]$ ruby -r google/protobuf -e'puts "hello"'
hello

I'm not sure if that's supported/expected, but it did get me unblocked. 😊

[blowmage]

I was able to get this to work by manually specifying the platform is ruby

This is the workaround we have been given when a new version of Ruby is released. The pre-compiled gems usually show up ~February, so until then we either have to set the platform and compile the gems when installing, or use the previous Ruby version until the pre-compiled gems are available.