From: simonpj <unknown>
Date: Mon, 22 Mar 1999 10:39:59 +0000 (+0000)
Subject: [project @ 1999-03-22 10:39:59 by simonpj]
X-Git-Tag: Approximately_9120_patches~6368
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=375c33b1a5085313b91329d396fa7d9c703bee46;p=ghc-hetmet.git

[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.
---

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}
 
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