Fail to Building native extensions. on Mac OSX 10.13.6

[fascox]

Building native extensions. This could take a while...
ERROR: Error installing solargraph:
ERROR: Failed to build gem native extension.

current directory: /Library/Ruby/Gems/2.3.0/gems/eventmachine-1.2.7/ext

/System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/bin/ruby -r ./siteconf20180912-38268-nmeu8e.rb extconf.rb
mkmf.rb can't find header files for ruby at /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/include/ruby.h

extconf failed, exit code 1

Gem files will remain installed in /Library/Ruby/Gems/2.3.0/gems/eventmachine-1.2.7 for inspection.
Results logged to /Library/Ruby/Gems/2.3.0/extensions/universal-darwin-17/2.3.0/eventmachine-1.2.7/gem_make.out

[castwide]

It looks like you don't have the Ruby development headers installed. The easiest way I know to get them on OSX is to install XCode.

Relevant links:

https://stackoverflow.com/questions/761521/when-i-try-sudo-gem-install-json-i-get-the-following-error

https://kevinpotgieter.wordpress.com/2012/12/06/ruby-gem-install-mkmf-rb-cant-find-header-files-for-ruby-problem/

[fascox]

xcode-select --install

and

sudo xcodebuild -license

solve the issue.

[acalism]

xcode-select --install

and

sudo xcodebuild -license

solve the issue.

After your commands, restarting macOS is required for me.

[xclidongbo]

macos 10.14.6.
same error.

[naffan2014]

same error

[Calebvh]

Same error, (trying to install Jazzy)
current directory: /Library/Ruby/Gems/2.3.0/gems/redcarpet-3.5.0/ext/redcarpet
xcode-select --install
and
sudo xcodebuild -license
and then subsequent restart have not worked, any suggestions?

[castwide]

You might need to install the command line tools: https://kevinpotgieter.wordpress.com/2012/12/06/ruby-gem-install-mkmf-rb-cant-find-header-files-for-ruby-problem/

[Calebvh]

Unfortunately I already have them installed, any other ideas?

[castwide]

This might be specific to MacOS 10.14. Apparently some development files got moved, or stopped getting installed by default, or...something. A couple of people have recommended running some variation of this:

open /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg

References:

• https://blog.driftingruby.com/updated-to-mojave/
• https://desiredpersona.com/install-jekyll-on-macos/
• https://stackoverflow.com/questions/46377667/docker-for-mac-mkmf-rb-cant-find-header-files-for-ruby

[Calebvh]

Yes, I was just about to post.
navigating to that package location and then entering:
sudo installer -pkg macOS_SDK_headers_for_macOS_10.14.pkg -target / 
This did the trick for me, thanks for your help!

[ChrisMash]

Running the .pkg in ~/Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg worked for me, so thanks for the tips!

Incidentally a colleague of mine didn't have that packages folder on his machine. I'd install the Xcode 11 update from the App Store and he'd deleted and installed from the download from the apple developer site, so there may be a difference for people if they don't use the App Store (maybe you can get the pkg from the apple developer site downloads page?)