From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 21835 invoked by alias); 27 Nov 2007 07:00:32 -0000 Received: (qmail 21825 invoked by uid 22791); 27 Nov 2007 07:00:31 -0000 X-Spam-Check-By: sourceware.org Received: from zigzag.lvk.cs.msu.su (HELO zigzag.lvk.cs.msu.su) (158.250.17.23) by sourceware.org (qpsmtpd/0.31) with ESMTP; Tue, 27 Nov 2007 07:00:26 +0000 Received: from Debian-exim by zigzag.lvk.cs.msu.su with spam-scanned (Exim 4.50) id 1IwuQc-0005rM-5m for gdb-patches@sources.redhat.com; Tue, 27 Nov 2007 10:00:23 +0300 Received: from localhost ([127.0.0.1] helo=ip6-localhost) by zigzag.lvk.cs.msu.su with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA:32) (Exim 4.50) id 1IwuQR-0005r3-Rf; Tue, 27 Nov 2007 10:00:08 +0300 From: Vladimir Prus To: Nick Roberts Subject: Re: [ob] unbreak MI Date: Tue, 27 Nov 2007 07:00:00 -0000 User-Agent: KMail/1.9.6 Cc: gdb-patches@sources.redhat.com References: <200708312244.58216.ghost@cs.msu.su> <18251.47321.156923.358334@kahikatea.snap.net.nz> In-Reply-To: <18251.47321.156923.358334@kahikatea.snap.net.nz> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200711271000.06151.ghost@cs.msu.su> Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2007-11/txt/msg00505.txt.bz2 On Tuesday 27 November 2007 09:27:37 Nick Roberts wrote: > > > Generally, with a NULL pointer, or and address that can't be dereferenced, > > > MI prints out the value field as value="". > > > > > > What is the problem in this case? Why isn't the right fix to add a > > > check_typedef somewhere? > > > > check_typedef? The original problem was that check_typedef was getting > > called on NULL pointer, so adding more check_typedef calls won't help. > > Probably: > > > > if (!gdb_type) > > ui_out_field_string (uiout, "value", ""); > > else if (mi_print_value_p (gdb_type, print_values)) > > ui_out_field_string (uiout, "value", varobj_get_value (var)); > > > > is the right logic? > > It's probably the right logic, but it seems to cure the symptom rather than the > cause. What I mean't, I guess, was where/how does check_typedef is get passed > a NULL pointer? And can't that call be conditioned (i.e. "add a *check* to > check_typedef") , e.g., something like: > > if (!gdb_type) > check_typedef (gdb_type) Just look at mi_print_value_p, and you'll see a call to check_typedef. Actually, the code previously looked like: if (type != NULL) type = check_typedef (type); It was changed in revision 1.38, with the following comment: 2007-08-28 Michael Snyder * mi/mi-cmd-var.c (mi_print_value_p): No longer necessary to check for null before calling check_typedef. However, apparently check_typedef still crashes when passed NULL, and it can be passed NULL. The original code, in fact, was in error too, because of this: return (TYPE_CODE (type) != TYPE_CODE_ARRAY && TYPE_CODE (type) != TYPE_CODE_STRUCT && TYPE_CODE (type) != TYPE_CODE_UNION); This will crash if 'type' is NULL. Testsuite fails to detect this because presently type is NULL only for C++ pseudo-fields ('public'/'private') and the code above is only executed for --simple-values. Does this clarify things? - Volodya