From 8c0eca3dccd58b41b226d3f3aad9a02a18bef6de Mon Sep 17 00:00:00 2001
From: Jan Stolarek <jan.stolarek@p.lodz.pl>
Date: Fri, 11 Sep 2015 22:29:02 +0200
Subject: [PATCH] Add assertions

---
 compiler/typecheck/FamInst.hs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/compiler/typecheck/FamInst.hs b/compiler/typecheck/FamInst.hs
index 49fc5fe8b0..978e92e34c 100644
--- a/compiler/typecheck/FamInst.hs
+++ b/compiler/typecheck/FamInst.hs
@@ -423,7 +423,8 @@ makeInjectivityErrors
    -> [CoAxBranch] -- ^ List of injectivity conflicts
    -> [(SDoc, SrcSpan)]
 makeInjectivityErrors tycon axiom inj conflicts
-  = let lhs             = coAxBranchLHS axiom
+  = ASSERT2( any id inj, text "No injective type variables" )
+    let lhs             = coAxBranchLHS axiom
         rhs             = coAxBranchRHS axiom
 
         are_conflicts   = not $ null conflicts
-- 
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