Compile time bit_size checking about deku

[sharksforarms]

I wonder if the assert could be done at compile time? Currently the assert is done at runtime which isn't ideal... For example, this would fail to compile (attempt to store 9 bits in 8 bit container)

struct DekuTest {
    #[deku(bits = "9")]
    field_a: u8,
}

[elast0ny]

This should be possible with https://docs.rs/static_assertions/1.1.0/static_assertions/macro.const_assert.html if you make the bit_size() function const

[elast0ny]

dam rust-lang/rust#57563 , i really thought const fn were stable for some reason...

I guess traits cannot contain const fns

const fn bit_size() -> usize;
   |     ^^^^^ trait fns cannot be const

It seems like bit_size() is just wrapping std::mem::size_of which is a const fn so maybe instead of having a bit_size trait, you could just call size_of() directly on the type ?

[sharksforarms]

No longer required: #19