[GHC] #909: problems building base package with --make; wired in things are assumed to not be in current package

[GHC]

#909: problems building base package with --make; wired in things are assumed to
not be in current package
-------------------------+--------------------------------------------------
    Reporter:  igloo     |        Owner:  simonpj
        Type:  bug       |       Status:  new    
    Priority:  normal    |    Milestone:  6.8    
   Component:  Compiler  |      Version:  6.4.2  
    Severity:  normal    |     Keywords:         
          Os:  Multiple  |   Difficulty:  Unknown
Architecture:  Multiple  |  
-------------------------+--------------------------------------------------
GHC currently assumes that wired in things are not in the current package.
 This causes problems when the base package is partially compiled (in
 particular, GHC.Base is built already) and you try to build the whole
 thing with --make.
 Each time it needs something from GHC.Base, GHC looks to see if it has
 been loaded from another package yet and, upon finding it hasn't, loads it
 from the current package.
 This results in it loading it multiple times, giving errors like:
 {{{
 GHC/Foo.hs:6:6:
     Overlapping instances for Eq Bool
       arising from use of `==' at GHC/Foo.hs:6:6-17
     Matching instances:
       instance Eq Bool -- Defined in GHC.Base
       instance Eq Bool -- Defined in GHC.Base
       instance Eq Bool -- Defined in GHC.Base
     In the expression: True == True
     In the definition of `foo': foo = True == True
 }}}
 This is now tested by base01 in the testsuite.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/909>
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