From: simonmar <unknown>
Date: Wed, 17 Oct 2001 13:13:36 +0000 (+0000)
Subject: [project @ 2001-10-17 13:13:36 by simonmar]
X-Git-Tag: Approximately_9120_patches~812
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=3b9d7c8181f6edd130fb93768e4f1e32977a738c;p=ghc-hetmet.git

[project @ 2001-10-17 13:13:36 by simonmar]
Add a comment about assumptions that we make about the result of
etaExpand.
---

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