build: Require C++-17

[davidgumberg]

std::is_standard_layout_v (used in util/no_destructor.h is not available until C++-17. This breaks building with some compilers.

Tested with clang 1f1c725b68b9d72b5cd3fc95c57ce4244bc85c8e (llvm/llvm-project@1f1c725)

google#1246
https://en.cppreference.com/w/cpp/types/is_standard_layout.html

I ran into this when trying to build with a master clang to test #54.

[fanquake]

If we are going to change this, I think you should just change it to C++20.

[l0rinc]

An alternative would be cherry-picking google#1251

[fanquake]

We aren't trying to retain C++11 compatibility?

[fanquake]

You could also update the CMake minimum required to 3.22 (just matching the Core minimum required).

[maflcko]

If this started happening recently in clang, i think we can wait for google to bump theirs (last bump: https://chromium.googlesource.com/chromium/src/tools/clang/+/4e2e7b926a033fc85695da101404f79b7ce2d7a7) and then wait for them to pull in one of the fixes?

[davidgumberg]

An alternative would be cherry-picking google#1251

I considered this fix, but it seems preferable to me to maintain a build flag patch over upstream rather than a code patch.

If this started happening recently in clang, i think we can wait for google to bump theirs (last bump: chromium.googlesource.com/chromium/src/tools/clang/+/4e2e7b926a033fc85695da101404f79b7ce2d7a7) and then wait for them to pull in one of the fixes?

This is already an issue with clang 20, e.g. my distro's included version of clang 20.1.6 fails to compile with this error.

[maflcko]

This is already an issue with clang 20, e.g. my distro's included version of clang 20.1.6 fails to compile with this error.

The downstream CI is using clang 20 ( https://github.com/bitcoin/bitcoin/blob/5757de4ddd37f9321ee6b338b40888fd3561fc00/ci/test/00_setup_env_native_fuzz.sh#L11, https://github.com/bitcoin/bitcoin/blob/5757de4ddd37f9321ee6b338b40888fd3561fc00/ci/test/01_base_install.sh#L53 , ...) is there a reason why it passes?