I know this is already merged, but as a confirmation, I built on an Ubuntu 20.04 aarch64 system with these changes. The build succeeded, and resulting binaries passed at least a few tests.

I think @asl originally put in this include for some particular variation (gcc vs clang perhaps, from the comment). It might be good if he can recall under what condition the include was required originally.

@ChrisDodd The particular change was added in #4609 in order to fix noexcept / no-noexcept problem of posix_memalign declaration. It's really a mess that depends on combination of compilers and libc flavours. Unfortunately, we have to do something like this as we re-define posix_memalign override later.

Thinking about this more, maybe we'd resort to cmake-stage check whether posix_memalign is defined with noexcept specifier or not. And use this for redefine.

I think @asl originally put in this include for some particular variation (gcc vs clang perhaps, from the comment). It might be good if he can recall under what condition the include was required originally.

Yes, I ran into this trying to compile a unity build with clang (#4595) and this was the fix we came up with.

Thinking about this more, maybe we'd resort to cmake-stage check whether posix_memalign is defined with noexcept specifier or not. And use this for redefine.

The CMake check sounds good, but I am not sure whether we can check the noexcept?