How to report bugs only seen with -flto?

[Georg-Johann Lay]

The reporting instructions from
http://gcc.gnu.org/bugs/#need
don't outline how to report bugs that only occur with -flto

Presumably, the bug to report is not a genuine LTO issue,
but only because the compiler sees code/bunch of input
files it does not see without -flto.

How should such problems that involve possibly many files
be reported?

Thanks for advice

Johann