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Re: Taking the address of a convenience variable value
- From: Andrew Cagney <cagney at gnu dot org>
- To: Bob Rossi <bob at brasko dot net>, Paul Dubuc <pdubuc at cas dot org>
- Cc: GDB Mailing List <gdb at sources dot redhat dot com>
- Date: Wed, 26 May 2004 13:24:34 -0400
- Subject: Re: Taking the address of a convenience variable value
- References: <40B37A92.6020106@cas.org> <20040525235958.GA30063@white>
On Tue, May 25, 2004 at 12:55:46PM -0400, Paul Dubuc wrote:
In the June 2004 issue of the C/C++ User's Journal (p. 24) there is an
article on how to write user-defined commands for gdb to examine the
contents of STL vectors, sets and maps. It looks extremely useful, so I
decided to try it modifying the commands for use with the GCC STL, but I
can't get some of the commands for sets and maps to work. It relies on a
tecnique that involves being able to take the address of a convenience
variable value, for example:
set $maptype = &$arg0._M_t._M_header->_M_value_field
set $maptypep = &$maptype
When I try this the 2nd statement gives me the error message
Attempt to take address of value not located in memory.
As you note, its trying to take the address of a convenience variable -
since convenience variables do not live in the inferior they don't have
an address.
Does:
set $maptype = &$arg0._M_t._M_header->_M_value_field
set $maptypep = &&$arg0._M_t._M_header->_M_value_field
or:
set $maptype = $arg0._M_t._M_header->_M_value_field
set $maptypep = &$arg0._M_t._M_header->_M_value_field
make sense?
The other, sigh, possability is that this was a ``feature'' and there's
been a regression :-/
Andrew
It doesn't work with gdb 5.3 or 6.1 on Solaris. The author claims that it
works on HP-UX, but I don't know why it would be any different.
Is there a way around this? Or is there another source of user-defined
commands that can be used to print the contents of STL containers in gdb?
Any help would be very much appreciated.
I read that article and was wondering if it was necessary to compile the
STL with -g and not with -O2. I don't think the author mentioned it, but
how else could all of the symbols in the STL work properly with GDB?
What does:
(gdb) paddr &$arg0._M_t._M_header->_M_value_field
display?