Mimimal compiler version

[etam]

In COMPILING.txt it says

Pioneer is known to build on the following platforms and build systems:
Linux: CMake with GCC 4.9+ or Clang 6+

The commit eada00c uses std::reduce, which comes from c++17. This raises the required minimal compiler version.

With g++ 7 cmake adds flag -std=gnu++1z, but the std::reduce is available since g++ 9.

[Gliese852]

Oh, apparently this is outdated information, we have been in C++17 for quite a long time

pioneer/CMakeLists.txt

Line 5 in c9abf3c

set(CMAKE_CXX_STANDARD 17)

Interesting that you had no problems for example with std::variant:

pioneer/src/core/Property.h

Line 52 in c9abf3c

using PropertyBase = std::variant<

or with std::string_view:

pioneer/src/core/StringUtils.cpp

Line 188 in c9abf3c

size_t SplitString::step(std::string_view str)

[etam]

I don't know if I have no problem with those other things. The compilation on the older system stops at the std::reduce and doesn't go any further.
It's not a problem for me and I'm not asking for compatibility.
It just means that COMPILING.txt needs a bit of an update.

[Gliese852]

Yeah, I just wanted to point out that commit eada00c does not raise the required minimal compiler version.

[impaktor]

So we should bump minimal GCC version from 4.9 to 9+?
And possibly clang from 6+ to 9+?

[Web-eWorks]

Clang 6 has 99% of C++17 support already present. All filed Defect Reports against C++17 are fully implemented as of Clang 9, though the only fixes which are not present in Clang 7 are to [[nodiscard]] constructors and structured bindings, which we do not make use of in the Pioneer codebase.

That being said, Clang 9 is ~4 years old at this point and can be expected to be present on most LTS distributions (e.g Ubuntu 20.04 uses Clang 10 as the default clang package). Feel free to bump the version. GCC 9 is also a good minimum base, as it is the first release with a stable ABI for C++17 (according to the GCC documentation).