On Sep 2, 2013, at 1:22 AM, Richard Sandiford <rdsandif...@googlemail.com>
wrote:
> What I'm saying is that the assert stops plain:
>
> max_wide_int x = wide_int_var;
Sorry for being slow. I see the point, indeed, from the preexisting code, we
did:
fixed_wide_int (const wide_int_ro w) : wide_int_ro (w) {
/* We only allow the same size in, as otherwise
we would not know how to extend it. */
gcc_assert (precision == bitsize);
}
to disallow it dynamically. Doing this, or pushing it further into the type
system so that it is caught a compile time, is fine.
I also like the passing of sign:
max_wide_int x = max_wide_int::from (wide_int_var, SIGNED);
max_wide_int x = max_wide_int::from (wide_int_var, UNSIGNED);
like this. In the previous code we did:
static inline fixed_wide_int from_wide_int (const wide_int& w) {
if (w.neg_p (SIGNED))
return w.sforce_to_size (bitsize);
return w.zforce_to_size (bitsize);
}
which is, as you point out, dangerous.
