fseq.cpp doesn't compile with g++

[nickbailey]

I fully understand you're targeting clang++ but everything else compiles with g++ -std=c++17 -fno-exceptions -fno-rtti -nodefaultlibs -fPIC -O2 -c -o ...

g++ (version 8.3.0) dislikes some templates:

fseq.cpp:830:26: error: could not convert ‘ss.F::_SeqSingle::t[0]’ from ‘const Tree’ {aka ‘const F::Union<F::_Boxed<F::_FragHeader>, F::Tree2, F::Tree3>’} to ‘F::Frag’ {aka ‘F::_Boxed<F::_FragHeader>’}
             return ss.t[0];

etc. Maybe it's just a case of selecting the right field in the union? It should return the first one, I guess? Or is it that the const qualifier is dropped? I found the definition of Union in fvalue.h but it's not obvious to me how it works yet.

Maybe you don't mind about g++ compatibility, but it would certainly increase your user-base among those for whom it's not easy to install clang.

[nickbailey]

That took me a while...
The following patch allows you to build libf++ with g++ and it still passes all the tests.

g++.patch.txt