From f1934472abf6ad317f1217a39e695600c0e82cf5 Mon Sep 17 00:00:00 2001
From: "simonpj@microsoft.com" <unknown>
Date: Tue, 11 May 2010 07:50:26 +0000
Subject: [PATCH] Fix Trac #4003: fix the knot-tying in checkHiBootIface

I had incorrectly "optimised" checkHiBootIface so that it forgot
to update the "knot-tied" type environment.

This patch fixes the HEAD
---
 compiler/ghc.mk                   |    7 -------
 compiler/typecheck/TcRnDriver.lhs |   18 +++++++++++-------
 2 files changed, 11 insertions(+), 14 deletions(-)

diff --git a/compiler/ghc.mk b/compiler/ghc.mk
index 3b12f7c..827ffb4 100644
--- a/compiler/ghc.mk
+++ b/compiler/ghc.mk
@@ -480,13 +480,6 @@ $(eval $(call compiler-hs-dependency,PrimOp,$(PRIMOP_BITS)))
 compiler/prelude/PrimOps_HC_OPTS += -fforce-recomp
 compiler/main/Constants_HC_OPTS  += -fforce-recomp
 
-# Workaround for #4003 in GHC 6.12.2.  It didn't happen in 6.12.1, and
-# will be fixed in 6.12.3.  Unfortunately we don't have a way to do
-# this for just stage1 in the build system.
-ifeq "$(GhcVersion)" "6.12.2"
-compiler/hsSyn/HsLit_HC_OPTS     += -fomit-interface-pragmas
-endif
-
 # Note [munge-stage1-package-config]
 # Strip the date/patchlevel from the version of stage1.  See Note
 # [fiddle-stage1-version] above.
diff --git a/compiler/typecheck/TcRnDriver.lhs b/compiler/typecheck/TcRnDriver.lhs
index 262bd73..649807e 100644
--- a/compiler/typecheck/TcRnDriver.lhs
+++ b/compiler/typecheck/TcRnDriver.lhs
@@ -566,15 +566,19 @@ checkHiBootIface
 
 		-- Check instance declarations
 	; mb_dfun_prs <- mapM check_inst boot_insts
-	; let tcg_env' = tcg_env { tcg_binds    = binds `unionBags` dfun_binds,
-				   tcg_type_env = extendTypeEnvWithIds local_type_env boot_dfuns }
-	      dfun_prs   = catMaybes mb_dfun_prs
-	      boot_dfuns = map fst dfun_prs
-	      dfun_binds = listToBag [ mkVarBind boot_dfun (nlHsVar dfun)
-				     | (boot_dfun, dfun) <- dfun_prs ]
+        ; let dfun_prs   = catMaybes mb_dfun_prs
+              boot_dfuns = map fst dfun_prs
+              dfun_binds = listToBag [ mkVarBind boot_dfun (nlHsVar dfun)
+                                     | (boot_dfun, dfun) <- dfun_prs ]
+              type_env'  = extendTypeEnvWithIds local_type_env boot_dfuns
+              tcg_env'   = tcg_env { tcg_binds = binds `unionBags` dfun_binds }
 
         ; failIfErrsM
-	; return tcg_env' }
+	; setGlobalTypeEnv tcg_env' type_env' }
+	     -- Update the global type env *including* the knot-tied one
+             -- so that if the source module reads in an interface unfolding
+             -- mentioning one of the dfuns from the boot module, then it
+             -- can "see" that boot dfun.   See Trac #4003
   where
     check_export boot_avail	-- boot_avail is exported by the boot iface
       | name `elem` dfun_names = return ()	
-- 
1.7.10.4