current CI action is not enough to catch even basic compilation error

[mjzk]

when I build for grandine binary, I got the error:

...
error: could not parse string literal: expected `,`
  --> ssz/src/byte_vector.rs:27:18
   |
27 |     Copy(bound = "N: ArrayLength<u8, ArrayType: Copy>"),
   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: could not parse bound
  --> ssz/src/byte_vector.rs:27:18
   |
27 |     Copy(bound = "N: ArrayLength<u8, ArrayType: Copy>"),
   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: could not parse string literal: expected `,`
  --> ssz/src/contiguous_vector.rs:36:18
   |
36 |     Copy(bound = "T: Copy, N: ArrayLength<T, ArrayType: Copy>"),
   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: could not parse bound
  --> ssz/src/contiguous_vector.rs:36:18
   |
36 |     Copy(bound = "T: Copy, N: ArrayLength<T, ArrayType: Copy>"),
   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0204]: the trait `std::marker::Copy` cannot be implemented for this type
  --> ssz/src/contiguous_vector.rs:43:12
   |
43 | pub struct ContiguousVector<T, N: ArrayLength<T>> {
   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
44 |     elements: GenericArray<T, N>,
   |     ---------------------------- this field does not implement `std::marker::Copy`
   |
note: the `std::marker::Copy` impl for `GenericArray<T, N>` requires that `<N as ArrayLength<T>>::ArrayType: std::marker::Copy`
  --> ssz/src/contiguous_vector.rs:44:15
   |
44 |     elements: GenericArray<T, N>,
   |               ^^^^^^^^^^^^^^^^^^

For more information about this error, try `rustc --explain E0204`.
error: could not compile `ssz` (lib) due to 5 previous errors

but cargo test --release --no-fail-fast is indeed successful now. So, the CI action passed.

This is a serious engineering problem, in fact. We should guarantee the compilation successful even for develop branch to allow catching the simplest mistakes.

I have checked the codes in ssz, this compilation error is just a mistake to derivative Copy for ArrayLength which is like this:

pub unsafe trait ArrayLength<T>: Unsigned {
    /// Associated type representing the array type for the number
    type ArrayType;
}

ArrayType here which is an associated type is not implemented in above code. It is trivial to fix. (I also can help a PR if needed.)

My concern is that our current CI action does not catch this simplest compilation error. I suggest we just add a binary build step in the action. I also can help a PR for this.