[odb-users] again: bad value ('/dev/null') for '-mtune=' switch

[MM]

Referring to earlier threads on this error, it seems the solution is to
rebuild odb.

Now, I've upgraded from Fedora38 to 39, and that upgraded g++ from
13.2.1 20231011 (Red Hat 13.2.1-4)
to
13.2.1 20231205 (Red Hat 13.2.1-6)

I would have guessed that this would not require a odb rebuild.

Strange

The cc1plus invocation that fails is

cc1plus -quiet -v -mtune=generic -mtune=generic -march=x86-64
-Wunknown-pragmas -Wno-deprecated -std=c++17 -version  -o -.s


This last argument -.s seems incorrecT?