Fix ICE in try_to_raw_bytes when array elements have mismatched

[reddevilmidzy]

close: #152683

After #152001, suffixed integer literals preserve their own type during const lowering, so try_to_raw_bytes could call .to_u8() on a scalar with size > 1, causing an ICE. Fix by using try_to_bits(Size::from_bytes(1)).ok() instead.

r? BoxyUwU

[rustbot]

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[reddevilmidzy]

Ah, it seems like the issue is resolved in #152492, but would it be better to revert the change to try_to_raw_bytes and just add the test?

The error changes like this:

#![expect(incomplete_features)]
#![feature(adt_const_params, generic_const_parameter_types, min_generic_const_args)]
fn foo<const N: usize, const A: [u8; N]>() {}

fn main() {
    foo::<_, { [0, 1u8, 2u32, 8u64] }>();
    //~^ ERROR the constant `8` is not of type `u8`
    //~| ERROR the constant `2` is not of type `u8`
}