Yeah. The problem with this, is that what happens if somebody stores the pointer? It introduces loads of special cases.

The most minimal solution would be to explicitly allow:

ushort e = *(cast ushort *)&y;
*(cast ushort *)&y = e;

and likewise for getting the raw mantissa into a ulong.

Simply two permissible reads, and two permissible writes, and only for x86. Essentially provides .exp | sign, and .mantissa as writable properties, but without syntax sugar. We could wrap it in a library to create syntax sugar.

It's really a hack, but this is one of those low-level primitives that needs to be provided as a special case, it's kind of an __asm feature.

I think the special case nature of this is unavoidable, it creates a host of problems if you allow general casting.