From: simonpj@microsoft.com <unknown>
Date: Mon, 19 Nov 2007 11:43:01 +0000 (+0000)
Subject: FIX Trac #1806: test for correct arity for datacon in infix pattern patch
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=91d5084fd9b9c6d2c5a91a0f0e00599ab0aa7954;p=ghc-hetmet.git

FIX Trac #1806: test for correct arity for datacon in infix pattern patch

Happily the fix is easy; pls merge
---

diff --git a/compiler/typecheck/TcPat.lhs b/compiler/typecheck/TcPat.lhs
index fca172f..f220154 100644
--- a/compiler/typecheck/TcPat.lhs
+++ b/compiler/typecheck/TcPat.lhs
@@ -717,9 +717,10 @@ tcConArgs data_con arg_tys (PrefixCon arg_pats) pstate thing_inside
     con_arity  = dataConSourceArity data_con
     no_of_args = length arg_pats
 
-tcConArgs data_con [arg_ty1,arg_ty2] (InfixCon p1 p2) pstate thing_inside
+tcConArgs data_con arg_tys (InfixCon p1 p2) pstate thing_inside
   = do	{ checkTc (con_arity == 2)	-- Check correct arity
 	 	  (arityErr "Constructor" data_con con_arity 2)
+	; let [arg_ty1,arg_ty2] = arg_tys	-- This can't fail after the arity check
 	; ([p1',p2'], tvs, res) <- tcMultiple tcConArg [(p1,arg_ty1),(p2,arg_ty2)]
 					      pstate thing_inside
 	; return (InfixCon p1' p2', tvs, res) }