Bug 38034

Summary:	Bizarre version comparison scheme
Product:	pkg-config	Reporter:	Jasper Lievisse Adriaanse <jasper>
Component:	src	Assignee:	Tollef Fog Heen <tfheen>
Status:	RESOLVED NOTABUG	QA Contact:
Severity:	major
Priority:	medium	CC:	dbn.lists
Version:	unspecified
Hardware:	All
OS:	All
Whiteboard:
i915 platform:		i915 features:

Description Jasper Lievisse Adriaanse 2011-06-07 06:12:22 UTC

As you may know OpenBSD has their own pkg-config implementation in perl. Whilst adding support for alpha/beta/rc suffixes and writing the tests for this I noticed as rather bizarre quirk in your pkg-config.

It treats 0.1.0beta2 being newer than 0.1.0:

$ pkg-config  --short-errors --errors-to-stdout --print-errors "vers1 > 0.1.0beta2" 
Requested 'vers1 > 0.1.0beta2' but version of Version test 1 is 0.1.0 
$

This strikes me as nothing but bizarre...same goes for 'rc' and all other suffixes. pkg-config thinks that a release canidate is newer than the actual release?

$ pkg-config  --short-errors --errors-to-stdout --print-errors "rc < 0.1.0" 
Requested 'rc < 0.1.0' but version of rc suffix test is 0.1.0rc2
$

Comment 1 Dan Nicholson 2012-04-16 18:05:59 UTC

pkg-config uses the rpmvercmp algorithm. Here's the upstream code from rpm if you're interested. I don't think there have been any significant code changes in years.

http://rpm.org/gitweb?p=rpm.git;a=blob;f=lib/rpmvercmp.c;hb=HEAD

rpmvercmp takes the stance that any alphabetical characters make the version _newer_ than the unadorned version. This works when you have a tweaked version that you want to be seen as newer than the regular version: 0.1 vs 0.1dbn. Unfortunately, it does not work for the alpha/beta/rc suffix.

Here's the redhat bug where they haggle about this:

https://bugzilla.redhat.com/show_bug.cgi?id=50977

I'm personally disinclined to change this algorithm now. Obviously, using a purely dotted decimal version will always do the right thing for you.

Feel free to reopen if you feel really strongly about and we can discuss some more, but for now I feel comfortable being compatible with rpm.

Comment 2 Tollef Fog Heen 2012-04-16 22:15:56 UTC

I'd like to say it even stronger: we're not going to change it now, since that is going to screw with people in the real world.

(If we're going to change algorithm, I'd like to move to the dpkg algorithm where you can be explicit about version number ordering (because you have ~ which is less than anything, including the empty string).

Comment 3 Dan Nicholson 2012-05-14 14:57:42 UTC

Apparently rpm grew ~ handling recently. We should import the changes to rpmvercmp(), it's not bad at all.

http://rpm.org/ticket/56
http://rpm.org/gitweb?p=rpm.git;a=commitdiff;h=db28221a4a48f6ee3c804c92314330637c808638

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