gcc and gdb bug caused by imacros usage (gdb emits only <command-line>)

[John Dennis]

On 01/18/2014 04:01 PM, Alan DeKok wrote:
> John Dennis wrote:
>> Recently when I was trying to perform symbolic debugging on components
>> built from the 3.x tree I discovered I was unable to get any source file
>> information in gdb, it would only emit <command-line> as the source
>> filename and I could not get gdb to list source, show it in a backtrace,
>> etc.
>>
>> Thanks to Nalin Dahyabhai who discovered the root cause, it's covered in
>> this bugzilla.
>>
>> https://bugzilla.redhat.com/show_bug.cgi?id=1004526
> 
>   Which isn't visible to anyone, apparently.

My apologizes.

> 
>> Apparently using -imacros causes the failure. To be honest I wasn't all
>> that familiar with -imacros myself. The workaround I came up with was to
>> replace -imacros in Make.inc.in with -include.
> 
>   That works for some platforms.  IIRC, the -imacro was added for a reason.
> 
>> I don't know which version of the gcc/gdb tool chain this shows up in or
>> if it's specific to how debuginfo packages are produced during the RPM
>> build process.
>>
>> But if you do hit this issue you'll discover it's almost impossible to
>> do any useful debugging, so heads up, HTH
> 
>   I'm inclined to ignore it for the short term.  I don't see it on any
> platforms I use, and the upstream gcc / gdb really should be fixed to
> work as advertised.

Yup, I wasn't suggesting it be changed upstream, it affects only a
subset of platforms. Rather it was a friendly bit of shared information
just in case someone does hit it. I had not a clue why gdb couldn't do
source level debugging and googling the issue didn't turn up any hints.
And yes, it's really a gcc/gdb issue.


-- 
John