Subject: bug#16994: 24.3; package.el dependency ordering incorrect (non-topological)

From: Andrew Childs <[email-masked]>
Date: Wed, 12 Mar 2014 16:50:56 +1300

package.el does not resolve dependencies in the correct order,
potentially resulting in packages installed before their
dependencies. This was reported in #14082 [1], but not fixed for all
cases. The packages should be arranged in topological order before
installation.

Consider the following package graph, with dependencies flowing left to
right:

      C
     / \            X---Z
    A   D--E         \ /    
     \ /              Y     
      B                

Or as an `archive-contents'

(1
 
 (a . [(1) ((b) (c)) "a" nil])
 (b . [(1) ((d))   "b" nil])
 (c . [(1) ((d))   "c" nil])
 (d . [(1) ((e))   "d" nil])
 (e . [(1) nil   "e" nil])
 
 (x . [(1) ((z) (y)) "x" nil])
 (y . [(1) ((z)) "y" nil])
 (z . [(1) nil "z" nil])
 )

For a, the only valid install orders are (e d b c a) or (e d c b a)
For x, the only valid install order is (z y x)

When installing `a' or `x', the ordering may be incorrect:

emacs-version:
    GNU Emacs 24.3.1 (x86_64-apple-darwin13.1.0, NS apple-appkit-1265.19)
 of 2014-03-12 on argon.cons.org.nz

[FAIL] install a = (c e d b a)
[FAIL] install x = (y z x)

emacs-version:
    GNU Emacs 24.3.50.1 (x86_64-apple-darwin13.1.0, NS apple-appkit-1265.19)
 of 2014-03-12 on argon.cons.org.nz

[FAIL] install a = (d c e b a)
[  OK] install x = (z y x)

For convenience, the complete test can be found on github [2].

[1] http://debbugs.gnu.org/cgi/bugreport.cgi?bug=14082
[2] https://gist.github.com/thefloweringash/9500216

Regards,
Andrew

In GNU Emacs 24.3.1 (amd64-portbld-freebsd10.0, Motif Version 2.3.4)
 of 2014-01-23 on 10R-amd64-default-job-01
Windowing system distributor `The X.Org Foundation', version 11.0.11404000
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