[commit: ghc] ghc-7.6: Fix missing case in coVarsOfTcCo (ef42189)

[Paolo Capriotti]

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

On branch  : ghc-7.6

http://hackage.haskell.org/trac/ghc/changeset/ef4218994742e8400a48b4d6e1ae7e6b67650dc4

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commit ef4218994742e8400a48b4d6e1ae7e6b67650dc4
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Wed Aug 22 16:13:56 2012 +0100

    Fix missing case in coVarsOfTcCo
    
    Reported by Ganesh, Trac #7178.  Fix is easy.
    
    MERGED from commit a0788a8b2ba19b7f3205010a71472342a75395f8

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 compiler/typecheck/TcEvidence.lhs |    6 ++----
 1 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/compiler/typecheck/TcEvidence.lhs b/compiler/typecheck/TcEvidence.lhs
index 09704fb..76408bd 100644
--- a/compiler/typecheck/TcEvidence.lhs
+++ b/compiler/typecheck/TcEvidence.lhs
@@ -245,11 +245,9 @@ coVarsOfTcCo tc_co
     go (TcLetCo {}) = emptyVarSet    -- Harumph. This does legitimately happen in the call
                                      -- to evVarsOfTerm in the DEBUG check of setEvBind
 
-    -- We expect only coercion bindings
+    -- We expect only coercion bindings, so use evTermCoercion 
     go_bind :: EvBind -> VarSet
-    go_bind (EvBind _ (EvCoercion co)) = go co
-    go_bind (EvBind _ (EvId v))        = unitVarSet v
-    go_bind other = pprPanic "coVarsOfTcCo:Bind" (ppr other)
+    go_bind (EvBind _ tm) = go (evTermCoercion tm)
 
     get_bndrs :: Bag EvBind -> VarSet
     get_bndrs = foldrBag (\ (EvBind b _) bs -> extendVarSet bs b) emptyVarSet