From 375c33b1a5085313b91329d396fa7d9c703bee46 Mon Sep 17 00:00:00 2001
From: simonpj <unknown>
Date: Mon, 22 Mar 1999 10:39:59 +0000
Subject: [PATCH] [project @ 1999-03-22 10:39:59 by simonpj] Fix the HsForAll
 case in TcMonoType.tc_type_kind so that it permits types
 like

	f :: forall a. Num a => (# a->a, a->a #)

Previously it insisted that the body of a for-all was a boxed
type, but 'f' makes perfect sense, and indeed occurs in interface
files as a result of CPR analysis.
---
 ghc/compiler/typecheck/TcMonoType.lhs |   16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/ghc/compiler/typecheck/TcMonoType.lhs b/ghc/compiler/typecheck/TcMonoType.lhs
index 6eb256d..93fb0a5 100644
--- a/ghc/compiler/typecheck/TcMonoType.lhs
+++ b/ghc/compiler/typecheck/TcMonoType.lhs
@@ -155,9 +155,19 @@ tc_type_kind (MonoDictTy class_name tys)
 tc_type_kind (HsForAllTy (Just tv_names) context ty)
   = tcExtendTyVarScope tv_names		$ \ tyvars -> 
     tcContext context			`thenTc` \ theta ->
-    tc_boxed_type ty			`thenTc` \ tau ->
-		-- Body of a for-all is a boxed type!
-    returnTc (boxedTypeKind, mkSigmaTy tyvars theta tau)
+    case theta of
+	[]    -> 	-- No context, so propagate body type
+		 tc_type_kind ty	`thenTc` \ (kind, tau) ->
+		 returnTc (kind, mkSigmaTy tyvars [] tau)
+
+	other -> 	-- Context; behave like a function type
+			-- This matters.  Return-unboxed-tuple analysis can
+			-- give overloaded functions like
+			--	f :: forall a. Num a => (# a->a, a->a #)
+			-- And we want these to get through the type checker
+
+		 tc_type ty		`thenTc` \ tau ->
+		 returnTc (boxedTypeKind, mkSigmaTy tyvars theta tau)
 \end{code}
 
 Help functions for type applications
-- 
1.7.10.4