unsafe precondition(s) violated: ptr::copy_nonoverlapping with rust 1.78

[m-dahl]

With rust 1.78 we now get panics on what I assume has to do with how we copy data from c message structs.

thread 'msg_types::tests::test_float_sequence' panicked at library/core/src/panicking.rs:156:5:
unsafe precondition(s) violated: ptr::copy_nonoverlapping requires that both pointer arguments are aligned and non-null and the specified memory ranges do not overlap

As a temporary fix you can downgrate to rust 1.77.

But we should investigate the root cause of the problem.

[m-dahl]

Rust 1.78 had in the release notes:

• Toggle assert_unsafe_precondition in codegen instead of expansion rust-lang/rust#120594 This change helps users catch undefined behavior in their code, though the details of how much is checked are generally not stable.

One of the checks now performed is that from_raw_parts no longer accepts a null ptr to the data (before the empty slice was returned). from_raw_parts is used a lot in the r2r code base. There may be up more of these issues that I didn't find yet.