fix bug #2056, tdebindings does not rely anymore on pkg-config #5

no more pkg-config for Ruby binding, only rbconfig.rb is needed.

It builds here with Ruby-1.8.7 and Ruby-2.6.5

Test on Debian 7.x (Wheezy):

checking for ruby... ruby
-e:1:in `fetch': key not found: "rubyarchhdrdir" (KeyError)
        from -e:1:in `<main>'

                  archdir /usr/lib/ruby/1.9.1/x86_64-linux,
                  sitearchdir /usr/local/lib/site_ruby/1.9.1/x86_64-linux,
                  sitedir /usr/local/lib/site_ruby/1.9.1,
                  rubylibdir /usr/lib/ruby/1.9.1,
                  libdir /usr/lib,
                  includedir /usr/include/ruby-1.9.1,
                  librubyarg -lruby-1.9.1,
                  cflags -I/usr/include/ruby-1.9.1 -I

followed by FTBFS:

In file included from /usr/include/ruby-1.9.1/ruby.h:32:0,
                 from Qt.cpp:49,
                 from libqtrubyinternal_la.all_cpp.cpp:2:
/usr/include/ruby-1.9.1/ruby/ruby.h:24:25: fatal error: ruby/config.h: No such file or directory
compilation terminated.

Ruby-1.9.1 rbconfig.rb does not seem to have rubyarchhdrdir, thanks for the testing.

The current version of the patch may cause FTBFS.

i don't see the need to push forwards in this direction with rbconfig.rb if we have to check regularly if the appropriate keys are there, it's no better than incrementing the ruby version with each new release. should i delete this?

@cethyel I made a small modification to your patch – now rubyarchhdrdir is used, if defined. Similarly, a test for rubyhdrdir is performed, so there is no need test based on Ruby version number.

Please test on your systems. I did a test on Debian 7.x (Wheezy) and Debian 10.x (Buster).

i don’t see the need to push forwards in this direction with rbconfig.rb if we have to check regularly if the appropriate keys are there, it’s no better than incrementing the ruby version with each new release. should i delete this?

Your solution looks good – this will allow us to get rid of reliance on the Ruby version number. I think there is no reason to discard this PR.

I'll test tomorrow, then you will choose to keep this or not, but I feel that Ruby's keys aren't consistent over time enough, a ruby version pushing that kind of changes over the last release and so on.

Patch tested and working on CentOS 6, 7 and 8.

@Francois Thanks for the testing.
@SlavekB we probably don't need RUBY_TEENY anymore.

@SlavekB Works for me, at least It builds fine here (ruby 2.6.5p114).
I've removed RUBY_TEENY btw.

t1.rb from qtruby/rubylib/tutorial/t1 does not work though, is this one of the (many) broken tutorials/examples? I fairly don't know!

To my knowledge, @MicheleC observed that many examples and tutorials in tdebindings did not work. However, it will be a different story than this pull-request. Nothing seems to prevent merge.

One small note: @cethyel your Signed-off-by is now duplicated. This is probably not needed. Please, can you make an amend commit log and push again?

@SlavekB: yes, tdebindings is mostly brokens and need work to fix it. There is an open PR, but it has been put on hold until R14.1.0 is released. It seems it needs some deep investigation 😧

   if test "$RUBY_VERSION" -ge "191"; then
      RUBY_INCLUDEDIR=`${RUBY_EXECUTABLE} -r rbconfig -e "puts RbConfig::CONFIG.fetch(%q(rubyhdrdir))"`
      RUBY_ARCH=`${RUBY_EXECUTABLE} -r rbconfig -e "puts RbConfig::CONFIG.fetch(%q(arch))"`
      RUBY_CFLAGS="-I${RUBY_INCLUDEDIR} -I${RUBY_INCLUDEDIR}/${RUBY_ARCH}"