[build2] build w gcc 8.1.1 + c++1y fails ( also gcc 8.2 )

[Boris Kolpackov]

Ok, thanks for setting up the SSH access, we've finally figured this
one out:

$ which g++
/usr/lib64/ccache/g++

So it appears that you have ccache setup as a silent intercept of
the gcc/g++ commands and ccache is unable to correctly handle the
way build2 compiles things.

If I remove /usr/lib64/ccache from PATH on your box then everything
works as expected.

Note that ccache pretends to be a "real" GCC:

$ /usr/lib64/ccache/g++ --version
g++ (GCC) 8.3.1 20190223 (Red Hat 8.3.1-2)
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

That is, there is no indication that it is a wrapper. So we cannot
even diagnose this situation.