CI C++17

[nilsnolde]

start with #3877 , still wait for more feedback. more a quick test.

[nilsnolde]

hm, of course some -WError kicks in.

on linux, seems like the date library has an uncaught_exception warning which some of our source files catch onto. it was apparently fixed for windows, but seems to be an issue for unix as well, as someone says it should say if __cplusplus >= 201703 here, at least that's what locally works. worth warming up probably and PR upstream, right? reading the author's answer again, it seems that's actually intentional, so we can keep defining it for ourselves.

on macos, there's a few others in meili mostly apparently, mostly error: 'iterator<std::forward_iterator_tag, const valhalla::meili::Label>' is deprecated [-Werror,-Wdeprecated-declarations]. at least that's in our control.. but also some in libosmium with error: 'result_of<osmium::io::detail::SerializeBlob ()>' is deprecated [-Werror,-Wdeprecated-declarations], which doesn't seem to be reported anywhere upstream. kinda weird, considering c++17 is in wide use, I'd have expected someone else to build with -Werror. but then again, seems to be macos(/xcode?) issue, builds fine on linux locally with the quick fix to overcome the date issue, hope CI will agree.

[nilsnolde]

ah good, the libosmium issue was already fixed in osmcode/libosmium@e933414. and was release with 2.17.2. we're on 2.16.0. so I guess moving up the version should solve that. might as well go all the way to 2.18.0 (lots of deprecated stuff was removed there, but 2.17.x should work for us).

[nilsnolde]

Back on my office machine, it also failed with gcc 12.2.0 with the same std::iterator deprecations when building the tests. Strange it works on CI Linux machines. There's a nice post about the why: https://www.fluentcpp.com/2018/05/08/std-iterator-deprecated/. I (tentatively) fixed it quickly and I could build the test locally.

Also upgraded to the latest libosmium release which went pretty smooth.