Fail to install psych 5.0.1 on Ubuntu with any Ruby version

[ahangarha]

I just tried to install psych 5.0.1 in a clean project and I couldn't. I tried this on Ruby version 2.7.5, 2.7.7 and 3.1.2. All fail. Since the minimum required ruby version is 2.4, I expect to not have any issue. I do this on Ubuntu machine. I also have failure in CI with again Ubuntu image.

The error with Ruby 2.7.5:

➜  test-psych-5.0.1-ruby-2.7.5 bundle add psych --version 5.0.1
Fetching gem metadata from https://rubygems.org/........
Resolving dependencies...
Fetching gem metadata from https://rubygems.org/........
Using bundler 2.1.4
Using stringio 3.0.4
Fetching psych 5.0.1
Installing psych 5.0.1 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    current directory: /home/sama/.rbenv/versions/2.7.5/lib/ruby/gems/2.7.0/gems/psych-5.0.1/ext/psych
/home/sama/.rbenv/versions/2.7.5/bin/ruby -I /home/sama/.rbenv/versions/2.7.5/lib/ruby/2.7.0 -r
./siteconf20221219-115915-pwmisp.rb extconf.rb
checking for yaml.h... no
yaml.h not found
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
	--with-opt-dir
	--without-opt-dir
	--with-opt-include
	--without-opt-include=${opt-dir}/include
	--with-opt-lib
	--without-opt-lib=${opt-dir}/lib
	--with-make-prog
	--without-make-prog
	--srcdir=.
	--curdir
	--ruby=/home/sama/.rbenv/versions/2.7.5/bin/$(RUBY_BASE_NAME)
	--with-libyaml-source-dir
	--without-libyaml-source-dir
	--with-yaml-0.1-config
	--without-yaml-0.1-config
	--with-pkg-config
	--without-pkg-config
	--with-libyaml-dir
	--without-libyaml-dir
	--with-libyaml-include
	--without-libyaml-include=${libyaml-dir}/include
	--with-libyaml-lib
	--without-libyaml-lib=${libyaml-dir}/lib

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /home/sama/.rbenv/versions/2.7.5/lib/ruby/gems/2.7.0/extensions/x86_64-linux/2.7.0/psych-5.0.1/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /home/sama/.rbenv/versions/2.7.5/lib/ruby/gems/2.7.0/gems/psych-5.0.1
for inspection.
Results logged to
/home/sama/.rbenv/versions/2.7.5/lib/ruby/gems/2.7.0/extensions/x86_64-linux/2.7.0/psych-5.0.1/gem_make.out

An error occurred while installing psych (5.0.1), and Bundler cannot continue.
Make sure that `gem install psych -v '5.0.1' --source 'https://rubygems.org/'` succeeds before
bundling.

In Gemfile:
  psych

and this is the content of the mentioned mkmf.log:

package configuration for yaml-0.1 is not found
find_header: checking for yaml.h... -------------------- no

"gcc -o conftest -I/home/sama/.rbenv/versions/2.7.5/include/ruby-2.7.0/x86_64-linux -I/home/sama/.rbenv/versions/2.7.5/include/ruby-2.7.0/ruby/backward -I/home/sama/.rbenv/versions/2.7.5/include/ruby-2.7.0 -I. -I/home/sama/.rbenv/versions/2.7.5/include    -g -O2 -fPIC conftest.c  -L. -L/home/sama/.rbenv/versions/2.7.5/lib -Wl,-rpath,/home/sama/.rbenv/versions/2.7.5/lib -L. -L/home/sama/.rbenv/versions/2.7.5/lib  -fstack-protector-strong -rdynamic -Wl,-export-dynamic     -Wl,-rpath,/home/sama/.rbenv/versions/2.7.5/lib -L/home/sama/.rbenv/versions/2.7.5/lib -lruby  -lm   -lc"
checked program was:
/* begin */
1: #include "ruby.h"
2: 
3: int main(int argc, char **argv)
4: {
5:   return !!argv[argc];
6: }
/* end */

"gcc -E -I/home/sama/.rbenv/versions/2.7.5/include/ruby-2.7.0/x86_64-linux -I/home/sama/.rbenv/versions/2.7.5/include/ruby-2.7.0/ruby/backward -I/home/sama/.rbenv/versions/2.7.5/include/ruby-2.7.0 -I. -I/home/sama/.rbenv/versions/2.7.5/include    -g -O2 -fPIC  conftest.c -o conftest.i"
conftest.c:3:10: fatal error: yaml.h: No such file or directory
    3 | #include <yaml.h>
      |          ^~~~~~~~
compilation terminated.
checked program was:
/* begin */
1: #include "ruby.h"
2: 
3: #include <yaml.h>
/* end */

--------------------

Am I missing something here?

[ahangarha]

It turned out that I need to install libyaml-dev on my machine so that this gem can get compiled. Is it meant to be this way?

Related PR: #541

[hsbt]

You should install libyaml-dev for Psych 5.x.