From e79bb2c10d66ec8f0c037e66c7d0a22aa887fdc1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=96mer=20Sinan=20A=C4=9Facan?= <omeragacan@gmail.com>
Date: Tue, 9 Aug 2016 22:30:56 +0000
Subject: Fix a bug in unboxed sum layout generation

We need to maintain the invariant that the layout fields are always sorted.

Two tests that were previously broken are added.
---
 compiler/simplStg/RepType.hs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

(limited to 'compiler/simplStg')

diff --git a/compiler/simplStg/RepType.hs b/compiler/simplStg/RepType.hs
index 7e42a866b0..ca8438eec1 100644
--- a/compiler/simplStg/RepType.hs
+++ b/compiler/simplStg/RepType.hs
@@ -199,7 +199,9 @@ ubxSumRepType constrs0 =
       | Just s' <- s `fitsIn` es
       = -- found a slot, use it
         s' : merge ess ss
-
+      | s < es
+      = -- we need a new slot and this is the right place for it
+        s : merge (es : ess) ss
       | otherwise
       = -- keep searching for a slot
         es : merge ess (s : ss)
-- 
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