From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <libc-hacker-return-8936-listarch-libc-hacker=sources.redhat.com@sourceware.org>
Received: (qmail 11691 invoked by alias); 27 Mar 2006 16:44:28 -0000
Received: (qmail 11663 invoked by uid 22791); 27 Mar 2006 16:44:28 -0000
X-Spam-Check-By: sourceware.org
Received: from sunsite.ms.mff.cuni.cz (HELO sunsite.mff.cuni.cz) (195.113.15.26)
    by sourceware.org (qpsmtpd/0.31) with ESMTP; Mon, 27 Mar 2006 16:44:27 +0000
Received: from sunsite.mff.cuni.cz (sunsite.mff.cuni.cz [127.0.0.1])
	by sunsite.mff.cuni.cz (8.13.1/8.13.1) with ESMTP id k2RGiFTg020620;
	Mon, 27 Mar 2006 18:44:15 +0200
Received: (from jj@localhost)
	by sunsite.mff.cuni.cz (8.13.1/8.13.1/Submit) id k2RGiFIf020619;
	Mon, 27 Mar 2006 18:44:15 +0200
Date: Mon, 27 Mar 2006 16:44:00 -0000
From: Jakub Jelinek <jakub@redhat.com>
To: Ulrich Drepper <drepper@redhat.com>
Cc: Glibc hackers <libc-hacker@sources.redhat.com>
Subject: [PATCH] Fix btowc and wctob in C++
Message-ID: <20060327164414.GB30252@sunsite.mff.cuni.cz>
Reply-To: Jakub Jelinek <jakub@redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
User-Agent: Mutt/1.4.1i
Mailing-List: contact libc-hacker-help@sourceware.org; run by ezmlm
Precedence: bulk
List-Subscribe: <mailto:libc-hacker-subscribe@sourceware.org>
List-Archive: <http://sourceware.org/ml/libc-hacker/>
List-Post: <mailto:libc-hacker@sourceware.org>
List-Help: <mailto:libc-hacker-help@sourceware.org>, <http://sourceware.org/ml/#faqs>
Sender: libc-hacker-owner@sourceware.org
X-SW-Source: 2006-03/txt/msg00042.txt.bz2

Hi!

Doing:

#include <wchar.h>

void *p = (void *) btowc;

at -O1+ in C++ (or similarly if for whatever reason the inline isn't always
inlined) results in endless recursion:

        .section        .text.btowc,"axG",@progbits,btowc,comdat
        .align 2
        .p2align 4,,15
        .weak   btowc
        .type   btowc, @function
btowc:
        jmp     btowc
        .size   btowc, .-btowc

The optimization really relies on the GNU C extern inline behavior.
We use the same __*_alias trick in plenty of the _FORTIFY_SOURCE headers,
but none of them is used for C++ nor for non-GCC compilers.
__USE_EXTERN_INLINES implies GCC 2.7+, so we just need to check for C++.

2006-03-27  Jakub Jelinek  <jakub@redhat.com>

	* wcsmbs/wchar.h (btowc, wctob): Don't optimize in C++.

--- libc/wcsmbs/wchar.h.jj	2006-03-17 08:37:07.000000000 +0100
+++ libc/wcsmbs/wchar.h	2006-03-27 18:38:07.000000000 +0200
@@ -321,6 +321,7 @@ __END_NAMESPACE_C99
 #ifdef __USE_EXTERN_INLINES
 /* Define inline function as optimization.  */
 
+# ifndef __cplusplus
 /* We can use the BTOWC and WCTOB optimizations since we know that all
    locales must use ASCII encoding for the values in the ASCII range
    and because the wchar_t encoding is always ISO 10646.  */
@@ -335,6 +336,7 @@ extern __inline int
 __NTH (wctob (wint_t __wc))
 { return (__builtin_constant_p (__wc) && __wc >= L'\0' && __wc <= L'\x7f'
 	  ? (int) __wc : __wctob_alias (__wc)); }
+# endif
 
 extern __inline size_t
 __NTH (mbrlen (__const char *__restrict __s, size_t __n,


	Jakub