Move to c++17

[omoerbeek]

Short description

Only compile tested with clang on OpenBSD so far.

Creating a PR so the CI and others can easily use this branch to test.

Checklist

I have:

• read the CONTRIBUTING.md document
• compiled this code
• tested this code
• included documentation (including possible behaviour changes)
• documented the code
• added or modified regression test(s)
• added or modified unit test(s)

[omoerbeek]

Old Boost is a hurdle.

[rgacogne]

Do we know which version of Boost fixed C++17 compatibility? Would it make sense to try C++14? I see some errors (in the fuzzers build) related to the removal of auto_ptr in C++17, which is still there in C++14.

[omoerbeek]

Do we know which version of Boost fixed C++17 compatibility? Would it make sense to try C++14? I see some errors (in the fuzzers build) related to the removal of auto_ptr in C++17, which is still there in C++14.

I searched for some explicitl statement about C++17 compatibility, but found none.

I am trying CentOS7 now, which has boost 1.53 but seems to have patched get_pointer.hpp. Lets see how much other stufff I encounter. For Ubuntu 16, (as used by the fuzzer) which has boost 1.57 another workaround might be needed. If it all does not work out, I'll try C++14

[rgacogne]

For Ubuntu 16, (as used by the fuzzer) which has boost 1.57 another workaround might be needed.

OSS-Fuzz intends to move to 20.04 eventually (google/oss-fuzz#3756) but I wouldn't hold my breath.

[omoerbeek]

So Unbuntu 16 as used by the fuzzer is a real problem. I was trying to set up a debug env like the fuzzer uses and found out: while the fuzzer build environment uses clang 12, the newest available clang from ubuntu xenial is 8. And if we use that we hit an issue with the c++ libs not being c++17 level. So getting a debug environment up and running is a hassle. Is there a more direct way to get the same env as the fuzzer uses?

[Habbie]

Is there a more direct way to get the same env as the fuzzer uses?

https://github.com/google/oss-fuzz/blob/master/infra/base-images/base-builder/Dockerfile ?

[rgacogne]

https://google.github.io/oss-fuzz/getting-started/new-project-guide/#testing-locally

[omoerbeek]

Ubuntu xenial is a swamp. It's boost 1.57 is using too much deprecated C++11 stuff that has been removed in C++17. Now going for C++14.

[omoerbeek]

Back to c++17 now that the fuzzer issue should be fixed

[omoerbeek]

Both CI and buildbot runs are fine. I needed to add one workaround in the bindbackend code.

[Habbie]

Two small things, looks good otherwise!

[omoerbeek]

Processed review comments and squashed it.