rustc-ap-rustc_error_codes 638.0.0

Automatically published version of the package `rustc_error_codes` in the rust-lang/rust repository from commit 30ca215b4e38b32aa7abdd635c5e2d56f5724494 The publishing script for this crate lives at: https://github.com/alexcrichton/rustc-auto-publish
Documentation 
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An attempt to implement the `Copy` trait for a struct failed because one of the
fields does not implement `Copy`. To fix this, you must implement `Copy` for the
mentioned field. Note that this may not be possible, as in the example of

```compile_fail,E0204
struct Foo {
    foo : Vec<u32>,
}

impl Copy for Foo { }
```

This fails because `Vec<T>` does not implement `Copy` for any `T`.

Here's another example that will fail:

```compile_fail,E0204
#[derive(Copy)]
struct Foo<'a> {
    ty: &'a mut bool,
}
```

This fails because `&mut T` is not `Copy`, even when `T` is `Copy` (this
differs from the behavior for `&T`, which is always `Copy`).