[commit: ghc] master: Simplify and improve coverage of ":info" instance lookup (eb8fb43)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/eb8fb434ff5e962a54247cacc5d3340972d5daf4/ghc

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

commit eb8fb434ff5e962a54247cacc5d3340972d5daf4
Author: Patrick Palka <patrick at parcs.ath.cx>
Date:   Thu Nov 14 17:40:55 2013 -0500

    Simplify and improve coverage of ":info" instance lookup
    
    During instance lookup, we can treat classes and data families like any
    other TyCon instead of special-casing them.  This approach, aside from
    being simpler, has the benefit of returning extra relevant instances for
    classes and data families.  For example, given
    
    class A a
    instance B (a :: Constraint)
    instance A B
    
    ":info B" will now also print "instance A B" where previously it didn't
    due to the special casing of class TyCons in lookupInsts.
    
    This improves upon the existing patch for Trac #4175


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eb8fb434ff5e962a54247cacc5d3340972d5daf4
 compiler/typecheck/TcRnDriver.lhs |    9 ---------
 1 file changed, 9 deletions(-)

diff --git a/compiler/typecheck/TcRnDriver.lhs b/compiler/typecheck/TcRnDriver.lhs
index 594d7fd..16b399b 100644
--- a/compiler/typecheck/TcRnDriver.lhs
+++ b/compiler/typecheck/TcRnDriver.lhs
@@ -2055,15 +2055,6 @@ tcRnGetInfo hsc_env name
 
 lookupInsts :: TyThing -> TcM ([ClsInst],[FamInst])
 lookupInsts (ATyCon tc)
-  | Just cls <- tyConClass_maybe tc
-  = do  { inst_envs <- tcGetInstEnvs
-        ; return (classInstances inst_envs cls, []) }
-
-  | isOpenFamilyTyCon tc || isTyConAssoc tc
-  = do  { inst_envs <- tcGetFamInstEnvs
-        ; return ([], familyInstances inst_envs tc) }
-
-  | otherwise
   = do  { (pkg_ie, home_ie) <- tcGetInstEnvs
         ; (pkg_fie, home_fie) <- tcGetFamInstEnvs
                 -- Load all instances for all classes that are