From 0eb7cf03da3783ca887d5de44d312cf6f3a4113c Mon Sep 17 00:00:00 2001
From: Simon Peyton Jones <simonpj@microsoft.com>
Date: Thu, 21 Feb 2019 09:34:01 +0000
Subject: [PATCH] Don't do binder-swap for GlobalIds
This patch disables the binder-swap transformation in the
(relatively rare) case when the scrutinee is a GlobalId.
Reason: we are getting Lint errors so that GHC doesn't
even validate. Trac #16346.
This is NOT the final solution -- it's just a stop-gap
to get us running again.
The final solution is in Trac #16296
---
compiler/simplCore/OccurAnal.hs | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/compiler/simplCore/OccurAnal.hs b/compiler/simplCore/OccurAnal.hs
index 5287817def6f..c3414b1fdb31 100644
--- a/compiler/simplCore/OccurAnal.hs
+++ b/compiler/simplCore/OccurAnal.hs
@@ -2402,9 +2402,14 @@ mkAltEnv env@(OccEnv { occ_gbl_scrut = pe }) scrut case_bndr
_ -> (env { occ_encl = OccVanilla }, Nothing)
where
- add_scrut v rhs = ( env { occ_encl = OccVanilla
- , occ_gbl_scrut = pe `extendVarSet` v }
- , Just (localise v, rhs) )
+ add_scrut v rhs
+ | isGlobalId v = (env { occ_encl = OccVanilla }, Nothing)
+ | otherwise = ( env { occ_encl = OccVanilla
+ , occ_gbl_scrut = pe `extendVarSet` v }
+ , Just (localise v, rhs) )
+ -- ToDO: this isGlobalId stuff is a TEMPORARY FIX
+ -- to avoid the binder-swap for GlobalIds
+ -- See Trac #16346
case_bndr' = Var (zapIdOccInfo case_bndr)
-- See Note [Zap case binders in proxy bindings]
--
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