Description of problem:
Package abseil-cpp fails to build from source in Fedora Rawhide.

Version-Release number of selected component (if applicable):
20210324.2-2.fc35

Steps to Reproduce:
koji build --scratch f36 abseil-cpp-20210324.2-2.fc35.src.rpm

Additional info:
This package is tracked by Koschei. See:
https://koschei.fedoraproject.org/package/abseil-cpp

> *** WARNING *** there are active plugins, do not report this as a bug unless you can reproduce it without enabling any plugins.
> Event                            | Plugins
> PLUGIN_FINISH_UNIT               | annobin: Generate final annotations
> PLUGIN_START_UNIT                | annobin: Generate global annotations
> PLUGIN_ALL_PASSES_START          | annobin: Generate per-function annotations
> PLUGIN_ALL_PASSES_END            | annobin: Register per-function end symbols
> during IPA pass: modref
> /builddir/build/BUILD/abseil-cpp-20210324.2/absl/flags/flag_test.cc:945:1: > internal compiler error: tree code 'template_type_parm' is not supported in LTO > streams
>   945 | }  // namespace
>       | ^
> Please submit a full bug report,
> with preprocessed source if appropriate.
> See <http://bugzilla.redhat.com/bugzilla> for instructions.

Also in:

> /builddir/build/BUILD/abseil-cpp-20210324.2/absl/flags/reflection_test.cc:265:1: internal compiler error: tree code 'template_type_parm' is not supported in LTO streams

This is probably a GCC bug.

If a short-term workaround is desired, options include disabling the tests (ugh) or disabling LTO (“%global _lto_cflags %{nil}”), which I’ve verified does allow the build to succeed.