Fwd: Re: ruby 1.8.7.x for rawhide

[Jim Meyering]

David Lutterkort wrote:
> On Tue, 2010-06-22 at 12:49 +0200, Jim Meyering wrote:
>> Mohammed Morsi wrote:
>> > I added this patch to my specfile as well, bumped the release, and
>> > updated the changelog to include your feedback.
>>
>> Hi again,
>>
>> rpmlint complains about this conditionally-applied patch:
>>
>>   %ifarch ppc64 s390x sparc64 x86_64
>>   %patch23 -p1
>>   %endif
>>
>> That patch (ruby-1.8.7-multilib.patch) is small enough that
>> I'll include it here, for reference:
>>
>> --- ruby-1.8.7-p249/mkconfig.rb.orig    2010-06-15 11:30:44.000000000 -0400
>> +++ ruby-1.8.7-p249/mkconfig.rb 2010-06-15 11:31:01.000000000 -0400
>> @@ -102,7 +102,7 @@
>>
>>  drive = File::PATH_SEPARATOR == ';'
>>
>> -prefix = '/lib/ruby/' + RUBY_VERSION.sub(/\.\d+$/, '') + '/' + RUBY_PLATFORM
>> +prefix = '/lib64/ruby/' + RUBY_VERSION.sub(/\.\d+$/, '') + '/' + RUBY_PLATFORM
>>
>> It is easy to perform the same task using an unconditional patch,
>> so I wrote this replacement:
>
> Couldn't we just get the right value from the environment ? I haven't
> looked if it's already in one of the standard env vars that rpmbuild
> sets up, but if bad comes to worst, couldn't we just do 'export
> LIB_PREFIX=%{_libdir}' in the spec file and then
>
>         prefix = ENV["LIB_PREFIX"].gsub(%r{^/usr}, "") + "/ruby" + RUBY_VERSION.sub(/\.\d+$/, '') + '/' + RUBY_PLATFORM

Using an rpm variable like that is more maintainable than enumerating
64-bit architectures or even using a regexp like /64$/ like I did.
However, while it would work when building via rpm tools, if someone
ever builds manually, they would have to know to set that envvar --
too easily missed or forgotten.

However, we can do something similar that might be more robust:
run something like this from the spec file:

    sed -i 's,/lib/ruby/,%{_whatever}/,' .../mkconfig.rb || exit 1

But that is fragile in its own way.  If mkconfig.rb changes, the sed
regexp may fail to match or it may match in some new place, introducing
an unwanted change.

We could mitigate that risk by adding tests
that would fail if our preconditions stop being met:

    # Ensure that the "sed" command below does the right thing.
    grep 'prefix = ./lib/ruby/. + RUBY_VERSION.sub' || exit 1
    test $(grep -c '/lib/ruby/') = 1 || exit 1

    # Use /lib64/ruby/ on a 64-bit system.
    sed -i 's,/lib/ruby/,%{_whatever}/,' mkconfig.rb || exit 1