[GHC] #10627: Regression: cabal install of numeric-prelude hangs

[GHC]

#10627: Regression: cabal install of numeric-prelude hangs
-------------------------------------+-------------------------------------
        Reporter:  George            |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  high              |               Milestone:  7.10.2
       Component:  Compiler          |                 Version:  7.10.2-rc2
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash                              |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
-------------------------------------+-------------------------------------

Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"d073c770209d3e7208059b3be8187a47c9181a3e/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="d073c770209d3e7208059b3be8187a47c9181a3e"
 Do not optimise RULE lhs in substRule

 This was causing Trac #10627.
 See Note [Substitute lazily] in CoreSubst.

 The bug was introduced by
    commit 30c17e7096919c55218083c8fcb98e6287552058
     Author: simonpj at microsoft.com <unknown>
     Date:   Thu Nov 25 17:23:56 2010 +0000
     Substitution should just substitute, not optimise

 The fix is not to optimise the RHS as well as not-optimising the LHS!
 The simplifier does the right thing in Simplify.simplRule
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10627#comment:18>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler