A constexpr Murmur3A hash

This is a constexpr (C++14) implementation or MurMur3A which can be compiled with clang or gcc. For more details, see my blog post about this library.

Usage

This is a header-only library. Include the header constexpr_murmur3.h and call the function ce_mm3::mm3_x86_32.

Is the value returned really a compile-time constant?

Yes. The following code would not compile otherwise:

using ce_mm3::mm3_x86_32;

template<int N>
struct printer
{
    printer() { std::cout << N << std::endl; }
};

printer<mm3_x86_32("Hello, world!", 0x9747b28c)> p;

Is this code well-formed according to the standard?

To be honest, I'm not entirely sure. I am not using any reinterpret_casts which would be the main culprit in implementing hash functions that deal operate on blocks of data. Feel free to comment on my post if you have any input on the issue.