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

[Johnoel Ancheta]

Does gdb just need to be updated?


On Sat, Feb 22, 2014 at 4:21 PM, John Sibert <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
>
> Visit the ADMB project http://admb-project.org/
>
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