From 3b9d7c8181f6edd130fb93768e4f1e32977a738c Mon Sep 17 00:00:00 2001
From: simonmar <unknown>
Date: Wed, 17 Oct 2001 13:13:36 +0000
Subject: [PATCH] [project @ 2001-10-17 13:13:36 by simonmar] Add a comment
 about assumptions that we make about the result of
 etaExpand.

---
 ghc/compiler/coreSyn/CorePrep.lhs |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/ghc/compiler/coreSyn/CorePrep.lhs b/ghc/compiler/coreSyn/CorePrep.lhs
index 5a4b636..298e599 100644
--- a/ghc/compiler/coreSyn/CorePrep.lhs
+++ b/ghc/compiler/coreSyn/CorePrep.lhs
@@ -427,6 +427,12 @@ mkLocalNonRec bndr dem floats rhs
 	--     code compiled without -O.  The case in point is data constructor
 	--     wrappers.
 	--
+	-- NB2: we have to be careful that the result of etaExpand doesn't
+	--    invalidate any of the assumptions that CorePrep is attempting
+	--    to establish.  One possible cause is eta expanding inside of
+	--    an SCC note - we're now careful in etaExpand to make sure the
+	--    SCC is pushed inside any new lambdas that are generated.
+	--
     getUniquesUs		`thenUs` \ us ->
     let
 	rhs' = etaExpand (exprArity rhs) us rhs bndr_ty
-- 
1.7.10.4