Issue #19403 has been updated by jcouball@yahoo.com (James Couball). I have also reported this in the `asdf` issue tracker [asdf-vm/asdf#1468](https://github.com/asdf-vm/asdf/issues/1468) ---------------------------------------- Bug #19403: Unable to Build Native Gems on Mac with Ruby 3.1.0+ https://bugs.ruby-lang.org/issues/19403#change-101624 * Author: jcouball@yahoo.com (James Couball) * Status: Open * Priority: Normal * ruby -v: 3.2.0 * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- # Unable to Build Native Gems on Mac with Ruby 3.1.0+ ## Problem In Ruby 3.1 and later installed by `rvm` or `asdf` on a Mac, `require 'mkmf'` aborts the script and reports the following error (the reported path is different depending on the Ruby install manager and the version of Ruby): ```text mkmf.rb can't find header files for ruby at /Users/couballj/.asdf/installs/ruby/3.2.0/lib/ruby/include/ruby.h You might have to install separate package for the ruby development environment, ruby-dev or ruby-devel for example. ``` and `RbConfig::CONFIG["rubyhdrdir"]` is set to an incorrect path: ```text "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/Users/couballj/.asdf/installs/ruby/3.2.0/include/ruby-3.2.0" ``` ## Expected Behavior Running `require 'mkmf'` should not abort and for my system/user using `asdf` installed Ruby 3.2.0 `RbConfig::CONFIG["rubyhdrdir"]` should be set to: ```text "/Users/couballj/.asdf/installs/ruby/3.2.0/include/ruby-3.2.0" ``` ## Details In Ruby 3.1 and later I can no longer build native gems (like nokoguru or redcarpet) on my Mac. I have tried this by installing Ruby with both `rvm` and `asdf`, both which have the same results. I receive the following error when trying to install (and build) these gems. For example, here is the error message when I try to run `gem install redcarpet`: ```text mkmf.rb can't find header files for ruby at /Users/couballj/.asdf/installs/ruby/3.2.0/lib/ruby/include/ruby.h You might have to install separate package for the ruby development environment, ruby-dev or ruby-devel for example. ``` I found that this error could be triggered just by running a Ruby script that requires `mkmf`. If `test.rb` contains this: ```ruby require 'mkmf' ``` Running this script: `ruby test.rb` Results in this output: ```text mkmf.rb can't find header files for ruby at /Users/couballj/.asdf/installs/ruby/3.2.0/lib/ruby/include/ruby.h You might have to install separate package for the ruby development environment, ruby-dev or ruby-devel for example. ``` Curiously, the reported directory does not exist. On my system, the path to `ruby.h` is `/Users/couballj/.asdf/installs/ruby/3.2.0/include/ruby-3.2.0/ruby.h` I found where in the Ruby code this error is reported in [mkmf.rb line 233](https://github.com/ruby/ruby/blob/master/lib/mkmf.rb#L224-L233). This code is trying to find `ruby.h` based on the value of `RbConfig::CONFIG["rubyhdrdir"]`. On my system, this value is: ```ruby "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/Users/couballj/.asdf/installs/ruby/3.2.0/include/ruby-3.2.0" ``` This value is a concatenation of `ENV['SDKROOT']` (which on my system is `/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk`) and the correct include directory path `/Users/couballj/.asdf/installs/ruby/3.2.0/include/ruby-3.2.0`. When I run the same code with Ruby 2.7.7, `RbConfig::CONFIG["rubyhdrdir"]` is set to the correct path: ```ruby "/Users/couballj/.asdf/installs/ruby/3.2.0/include/ruby-3.2.0" ``` ## Possible Cause I have found a possible cause in [commit fd97862](https://github.com/ruby/ruby/commit/fd978621ccbc9519afc05ad031ba2518e9a6f379...) in line 127 of mkconfig.rb. This change prepends `ENV['SDKROOT']` to the include directory that is used to build `RbConfig::CONFIG["rubyhdrdir"]`. While there may have been good reason for that change, in my case this change causes `require 'mkmf'` to fail in my use case. ## Work Around I have been able to work around this issue by creating a symbolic link from `/Users /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/Users` to `/Users` with the following command: ```shell sudo ln -s /Users /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/Users ``` This change will works for both `rvm` and `asdf` no matter what version of Ruby is installed. -- https://bugs.ruby-lang.org/