[gentoo-user] How to trace down compilation issues if the compilation does not break...?

Hi,

the usual event, if something comilation-related, is a list
of all files, which could be examined to find the problem
and a lot of styff put under /var/tmp/portage...

I have a problem with the Krita-installation and I think it
is a wrong way of configuration of the compilation problem.

The problem with this problem is, that the compilation process
is successful and all files will be removed from /var/tmp/portage
afterwards.

I checked the manpage of emerge to find an option to prevent the
deletion of the remainders, but found nothing.

Is there a way to keep these?

Thanks a lot in advance for any help!
Cheers!
Meino