[Developers] debugging issues; -g is now useless with gdb

[John Sibert]

Perhaps.

I have
$ gdb --version
GNU gdb (Ubuntu/Linaro 7.4-2012.04-0ubuntu2.1) 7.4-2012.04

But
https://www.sourceware.org/gdb/
announced
February 6th, 2014: *GDB 7.7 Released!*
The latest version of GDB, version 7.7, is available for download 
<https://www.sourceware.org/gdb/download/>.



John Sibert
Emeritus Researcher, SOEST
University of Hawaii at Manoa
Honolulu HI (GMT-10)
808-294-3842

Visit the ADMB project http://admb-project.org/

On 02/22/2014 08:11 PM, Johnoel Ancheta wrote:
> Does gdb just need to be updated?
>
>
> On Sat, Feb 22, 2014 at 4:21 PM, John Sibert <sibert at hawaii.edu 
> <mailto:sibert at hawaii.edu>> wrote:
>
>     Starting with gcc-4.8 (or perhaps gcc-4.7) the compiler does not
>     generate debugging information that is completely compatible with
>     gdb. As a result the message "No symbol 'foo' in current context."
>     is emitted every time an attempt is made to print or display a
>     variable. Searching on the message yields a lot of useless advice
>     about suppressing optimization. While is this advice is more or
>     less correct, it does not eliminate the message or permit
>     examining a variable. After a lot of further searching on
>     stackoverflow, the solution is apparently to replace -g or -ggdb
>     with "-g -gdwarf-2". Further farting around will reveal whether
>     both -g and -gdwarf-2 are necessary. (Reverting to gcc-4.6.3 also
>     solves the problem, but seems dumb.)
>
>     The ADMB make scripts for gcc use -ggdb and will not produce the
>     desired result.
>
>     Also, IMHO, there is no point in compiling with both the OPT_LIB
>     macro and the debug flags. It won't tell you where you walked out
>     of an array in the optimized libraries. If you want to debug
>     something use the safe libraries.
>
>     John
>
>     -- 
>     John Sibert
>     Emeritus Researcher, SOEST
>     University of Hawaii at Manoa
>     Honolulu HI (GMT-10)
>     808-294-3842 <tel:808-294-3842>
>
>     Visit the ADMB project http://admb-project.org/
>
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>