How can I get the alignment of a class instance? I know how to
get the size:
__traits(classInstanceSize, T)
But, there doesn't appear to be any equivalent trait for the
alignment.
(Knowing the alignment of a class instance is required to
correctly use core.lifetime.emplace, or do any sort of manual
allocation of class instances. I know that I can conservatively
estimate the alignment as nextPow2(__traits(classInstanceSize,
T)), but that is nearly always a wasteful over-estimate.
I've come across others' code online that simply assumes the
alignment is size_t.alignof, but that's not right either because
a class instance may contain SIMD vectors with higher alignments,
or it may be aligned to a cache line size for efficient
multi-threaded access.)
