[commit: ghc] ghc-7.2: Implement a findCycle function in Digraph, (f1158aa)

[Ian Lynagh]

Repository : ssh://darcs.haskell.org//srv/darcs/ghc

On branch  : ghc-7.2

http://hackage.haskell.org/trac/ghc/changeset/f1158aa8dc5302dc5428c28305ffa94ca51443ce

>---------------------------------------------------------------

commit f1158aa8dc5302dc5428c28305ffa94ca51443ce
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Fri Jul 22 08:56:42 2011 +0100

    Implement a findCycle function in Digraph,
    and use it to report module loops nicely
    
    This fixes Trac #5307. Now we get
    
        Module imports form a cycle:
                 module `M8' (.\M8.hs)
                imports `M1' (M1.hs)
          which imports `M9' (.\M9.hs-boot)
          which imports `M8' (.\M8.hs)
    
    And the algorithm is linear time.

 compiler/main/GhcMake.hs   |   67 +++++++++++++---------------------
 compiler/utils/Digraph.lhs |   85 +++++++++++++++++++++++++++++++++++++++----
 compiler/utils/Util.lhs    |    6 +++-
 3 files changed, 107 insertions(+), 51 deletions(-)


Diff suppressed because of size. To see it, use:

    git show f1158aa8dc5302dc5428c28305ffa94ca51443ce