[commit: ghc] wip/rae: Increase an InScopeSet for a substitution (6e2e5e3)

[git at git.haskell.org]

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

On branch  : wip/rae
Link       : http://ghc.haskell.org/trac/ghc/changeset/6e2e5e3b22bb7534162060daded95eb02f236199/ghc

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

commit 6e2e5e3b22bb7534162060daded95eb02f236199
Author: Richard Eisenberg <eir at cis.upenn.edu>
Date:   Tue Apr 12 12:00:55 2016 -0400

    Increase an InScopeSet for a substitution
    
    This is a further fix for #11814


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

6e2e5e3b22bb7534162060daded95eb02f236199
 compiler/types/FamInstEnv.hs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/compiler/types/FamInstEnv.hs b/compiler/types/FamInstEnv.hs
index 020dd78..62906dd 100644
--- a/compiler/types/FamInstEnv.hs
+++ b/compiler/types/FamInstEnv.hs
@@ -515,7 +515,8 @@ compatibleBranches (CoAxBranch { cab_lhs = lhs1, cab_rhs = rhs1 })
   = case tcUnifyTysFG (const BindMe) lhs1 lhs2 of
       SurelyApart -> True
       Unifiable subst
-        | Type.substTy subst rhs1 `eqType` Type.substTy subst rhs2
+        | Type.substTyAddInScope subst rhs1 `eqType`
+          Type.substTyAddInScope subst rhs2
         -> True
       _ -> False