mi/2309: Internal error (Assertion failure) on "-var-update" command

mi/2309: Internal error (Assertion failure) on "-var-update" command

[Nils.Hagge]

>Number:         2309
>Category:       mi
>Synopsis:       Internal error (Assertion failure) on "-var-update" command
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    unassigned
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Fri Aug 31 15:38:01 UTC 2007
>Closed-Date:
>Last-Modified:
>Originator:     Nils Hagge
>Release:        version 6.5
>Organization:
>Environment:
- Windows/Cygwin AND 
- SuSE Linux 10.2
>Description:
How to reproduce:

Take the following program:
#include <stdio.h>

struct { 
	struct { int secondA; int secondB; } firstA; 
	int firstB; 
} *p;

int main(void) {                         // line 18
    int i = 20;                          // line 19
    printf("!!!Hello World!!!\n");       
    printf("i = %d\n", ++i);
    p = 0;
    return 0;
}

compile with debug info.

Start gdb as follows:

gdb -q -nw -i mi Debug/TestLocalDebug.exe
---------------

The following MI dialog 
- starts the program and stops in main (line 19)
- create two watch expression
  - "p" and
  - "p->firstA.secondB"
- the second of which cannot be evaluated since p is not sensibly initialized.
- the command -var-expression-evaluate works and an error is indicated.
- the command -var-update brings gdb to crash on the "bad expression, see below:

-----------------------------------------------------

adhani1@ad026663nb$ gdb -q -nw -i mi Debug/TestLocalDebug.exe
(gdb)
break main
&"break main\n"
~"Breakpoint 1 at 0x401075: file ../src/TestLocalDebug.c, line 18.\n"
^done
(gdb)
2-exec-run
2^running
(gdb)
2*stopped,reason="breakpoint-hit",bkptno="1",thread-id="1",frame={addr="0x004010
75",func="main",args=[],file="../src/TestLocalDebug.c",fullname="/cygdrive/d/workspaces/rtpdebugger-devel-runtime/TestLocalDebug/src/TestLocalDebug.c", line="18"}
(gdb)
3 info program
&"info program\n"
~"\tUsing the running image of child thread 1924.0x14bc.\n"
~"Program stopped at 0x401075.\n"
~"It stopped at breakpoint 1.\n"
3^done
(gdb)
4 info threads
&"info threads\n"
~"  2 thread 1924.0xc8  0x7c90eb94 in ntdll!LdrAccessResource ()\n"
~"   from /cygdrive/c/WINNT/system32/ntdll.dll\n"
~"* 1 thread 1924.0x14bc  main () at ../src/TestLocalDebug.c:18\n"
4^done
(gdb)
5-var-create - * p
5^done,name="var1",numchild="2",type="struct {...} *"
(gdb)
6-var-create - * p->firstA.secondB
6^done,name="var2",numchild="0",type="int"
(gdb)
8-var-evaluate-expression var1
8^done,value="0x0"
(gdb)
9-var-evaluate-expression var2
&"Cannot access memory at address 0x4\n"
9^error,msg="Cannot access memory at address 0x4"
(gdb)
11-data-evaluate-expression p->firstA.secondB
&"Cannot access memory at address 0x4\n"
11^error,msg="Cannot access memory at address 0x4"
(gdb)
12-exec-next 1
12^running
(gdb)
12*stopped,reason="end-stepping-range",thread-id="1",frame={addr="0x0040107a", func="main",args=[],file="../src/TestLocalDebug.c",fullname="/cygdrive/d/workspaces/rtpdebugger-devel-runtime/TestLocalDebug/src/TestLocalDebug.c",line="19"}
(gdb)
13-var-update var1
13^done,changelist=[]
(gdb)
14-var-update var2
~"/netrel/src/gdb-20060706-2/gdb/varobj.c:1471: internal-error: my_value_equal:
Assertion `!value_lazy (val1)' failed.\n"
~"A problem internal to GDB has been detected,\n"
~"further debugging may prove unreliable.\n"
~"Quit this debugging session? (y or n) "



>How-To-Repeat:
replay the dialog
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:

Re: mi/2309: Internal error (Assertion failure) on "-var-update" command

[Aleksandar Ristovski]

The following reply was made to PR mi/2309; it has been noted by GNATS.

From: Aleksandar Ristovski <ARistovski@qnx.com>
To: gdb-gnats@sources.redhat.com
Cc:  
Subject: Re: mi/2309: Internal error (Assertion failure) on "-var-update" 
	command
Date: Thu, 10 Jan 2008 17:16:05 -0500

 Please check if this patch resolves the problem:
 
 http://sourceware.org/ml/gdb-patches/2008-01/msg00250.html
 
 
 ---
 Aleksandar

Re: mi/2309: Internal error (Assertion failure) on "-var-update" command

[Aleksandar Ristovski]

The following reply was made to PR mi/2309; it has been noted by GNATS.

From: Aleksandar Ristovski <ARistovski@qnx.com>
To: gdb-gnats@sources.redhat.com
Cc:  
Subject: Re: mi/2309: Internal error (Assertion failure) on "-var-update" 
	command
Date: Thu, 10 Jan 2008 15:51:45 -0500

 Another test case where this happens:
 
 NOTE: The problem occurs on both current snapshot from CVS  and  gdb 6.7
 NOTE2: gdb 6.6 seems to not have this issue.
 
 Compilers tried: 4.1.1, 4.2.1 
 
 Sample code:
 ============= main.cc ====================
 class B {
 public:
 	int b;
 	virtual ~B() {};
 };
 class A: public B {
 public:
 	int a;
 };
 
 int main(int argc, char **argv) {
 	B * b = new A();
 	b->b = 2;
 	A * a = dynamic_cast<A*>(b);
 	a->a = 1;
 }
 ========================================
 
 ====== initcrash =======================
 file test
 -break-insert main
 -exec-run
 -var-create - * b
 -var-list-children var1
 -var-list-children var1.public
 ========================================
 
 To compile:
 g++ -g main.cc -o test
 
 To reproduce assertion:
 gdb -i=mi < initcrash
 
 
 gdb version:
 gdb --version
 GNU gdb 6.7.50.20080110-cvs
 Copyright (C) 2008 Free Software Foundation, Inc.
 License GPLv3+: GNU GPL version 3 or later
 <http://gnu.org/licenses/gpl.html>
 This is free software: you are free to change and redistribute it.
 There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
 and "show warranty" for details.
 This GDB was configured as "i686-pc-linux-gnu".
 
 
 ---
 Aleksandar Ristovski
 QNX Software Systems
 

Re: mi/2309: Internal error (Assertion failure) on "-var-update" command

[Nick Roberts]

The following reply was made to PR mi/2309; it has been noted by GNATS.

From: Nick Roberts <nickrob@snap.net.nz>
To: gdb-gnats@sources.redhat.com, nobody@sources.redhat.com,
	Nils.Hagge@siemens.com, gdb-prs@sources.redhat.com
Cc:  
Subject: Re: mi/2309: Internal error (Assertion failure) on "-var-update" command
Date: Fri, 4 Jan 2008 19:09:58 +1300

 http://sourceware.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gdb&pr=2309
 
 This has been fixed for GDB in the CVS repository.  It fails in GDB 6.6 but can
 you see if it works for GDB 6.7 too?
 
 -- 
 Nick                                           http://www.inet.net.nz/~nickrob

Re: mi/2309: Internal error (Assertion failure) on "-var-update" command

[Daniel Jacobowitz]

The following reply was made to PR mi/2309; it has been noted by GNATS.

From: Daniel Jacobowitz <drow@false.org>
To: Nils.Hagge@siemens.com
Cc: gdb-gnats@sources.redhat.com
Subject: Re: mi/2309: Internal error (Assertion failure) on "-var-update"
	command
Date: Fri, 31 Aug 2007 11:51:39 -0400

 On Fri, Aug 31, 2007 at 03:35:07PM -0000, Nils.Hagge@siemens.com wrote:
 > >Release:        version 6.5
 
 Please try a current GDB snapshot.  I believe this is already fixed.
 
 -- 
 Daniel Jacobowitz
 CodeSourcery