Compilation of Ruby should fail when libyaml is not present on system
Quoting from :
If libyaml is not installed properly, you cannot compile Psych; no YAML library is available by default. You will see the following message in the build log:
yaml.h is missing. Please install libyaml.
Failed to configure psych. It will not be installed.
More concretely, you cannot invoke gem command:
<top (required)>':require': cannot load such file -- psych (LoadError)
It seems your ruby installation is missing psych (for YAML output).
To eliminate this warning, please install libyaml and reinstall your ruby.
Since this seems to be real world problem [ruby-core:49416], the compilation should fail with error message, to avoid producing broken Ruby installation