The following code:

use std::ops::Deref; struct NotCopy { inner: bool } struct Foo { first: NotCopy, second: NotCopy } impl Deref for Foo { type Target = NotCopy; fn deref(&self) -> &NotCopy { &self.second } } fn use_it(val: Foo) { let inner = val.first; //val.second; val.inner; }

gives the following error message:

error[E0382]: borrow of moved value: `val` --> src/lib.rs:22:5 | 20 | let inner = val.first; | --------- value moved here 21 | //val.second; 22 | val.inner; | ^^^ value borrowed here after partial move | = note: move occurs because `val.first` has type `NotCopy`, which does not implement the `Copy` trait 

This error occurs because val.inner performs a deref-coercion to access the field inner on NotCopy. However, this is not mentioned in the error message - we instead refer to val being 'borrowed' by what appears to be a normal field access.

If val.second is uncommented, and val.inner commented out, the code compiles successfully. This may be very confusing to users who don't realize that only one field involves a deref-coercion, as it looks like either access should be allowed.

When a move error occurs, we should explicitly mention any deref-coercions that occur, and explain why they prevent the code from compiling.