Compilation error with clang 14 on Apple silicon 13.6.4

[fuhlig1]

When trying to compile the test suite on an Apple silicon with macosx 13.6.4 and Apple clang 14 I get the following error

CC=clang CXX=clang++ make

gnu++2b: test extensions (-Wall -Wextra -Wpedantic -Wno-attributes -Wno-unknown-pragmas -Wno-psabi -Wno-self-assign-overloaded -Wno-deprecated -I/Users/uhlig/vir-simd)
In file included from vir/test.cpp:7:
In file included from /Users/uhlig/vir-simd/vir/simdize.h:19:
vir/simd_permute.h:176:23: error: no template named 'bit_cast' in namespace 'std'; did you mean 'detail::bit_cast'?
                const VecType vec = std::bit_cast<VecType>(v);
                                    ^~~~~~~~~~~~~
                                    detail::bit_cast
vir/detail.h:155:5: note: 'detail::bit_cast' declared here
    bit_cast(const From& x)
    ^

[mattkretz]

Oh, this is missing an #include <bit> in simdize.h. Seems to be indirectly included on my side.

[fuhlig1]

This is what I tried first but this doesn't help. The #include <bit> is in simd_permute.h.

[mattkretz]

According to https://en.cppreference.com/w/cpp/compiler_support std::bit_cast was added in Apple Clang 14.0.3. So maybe it's actually not available at all on your side?

[mattkretz]

If that's the case then we need to work around it via __cpp_lib_bit_cast (or __builtin_bit_cast - does that work?)

[fuhlig1]

According to https://en.cppreference.com/w/cpp/compiler_support std::bit_cast was added in Apple Clang 14.0.3. So maybe it's actually not available at all on your side?

Since I am using Apple Clang 14.0.0 this is probably the issue.

[fuhlig1]

If that's the case then we need to work around it via __cpp_lib_bit_cast (or __builtin_bit_cast - does that work?)

I think __builtin_bit_cast works. After changing the code the compilation now fails with missing functions from std::ranges. If I read the table correctly this functions are also missing in Apple clang 14.

[mattkretz]

OK, and I thought GCC 9 (in CI) was old 😅. So I guess the code needs way more #ifdef on feature test macros.

[mattkretz]

The master branch does not rely on std::bit_cast directly anymore (if I got it right). Can you confirm Apple builds now?

[mattkretz]

Clang 14 with libc++ is now part of the CI builds (and passes). Still not Apple Clang, but at least somewhat closer.