real.sizeof

[Dom DiSc]

On Monday, 5 February 2024 at 17:28:38 UTC, Iain Buclaw wrote:
>
> Padding.
>
> x86 ABI prefers things to be aligned, so on x86 it's 12 bytes, 
> x86_64 16 bytes.  In both cases you don't get any extra 
> precision over the 80-bits that x87 gives you.

This is exactly what I mean. The ABI may pad it, but sizeof 
should still give the number of bytes that are really used (not 
counting the gaps).
Or is there a way to change the alignment of basic types?

In my code I wanted do decide if the processor uses 
double-extended or quadruple as real depending on the sizeof.
But now I learned I cannot rely on this. Fortunately there is 
mant_dig, which gives the correct info.

At least in an array of real I would expect no padding, like in 
an array of bool (except for odd length).