Fix appending attributes instead of inserting them

[Luctins]

This fixes a warning (legacy_derive_helpers) about outer struct attributes being used before being declared. This warning is slated to become a hard error in the future.

Trying to use outer struct attributes with strikethrough work, but seems like it may fail in the future.

Trying to compile a minimal example shows:

warning: derive helper attribute is used before it is introduced
 --> src/main.rs:8:11
  |
4 |     #[strikethrough[derive(Debug, Serialize, Deserialize)]]
  |                                   --------- the attribute is introduced here
...
8 |         #[serde(transparent)]
  |           ^^^^^
  |
  = note: `#[warn(legacy_derive_helpers)]` on by default
  = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
  = note: for more information, see issue #79202 <https://github.com/rust-lang/rust/issues/79202>

Indicating probably that it adds the #[derive(Attr)] after the outer attributes.

Tracking issue: rust-lang/rust#79202

[Luctins]

Sorry for the force pushes, forgot to use the correct key+email+username combo

[Luctins]

mwe:

src/main.rs

use serde::{Serialize, Deserialize};

structstruck::strike!{
    #[strikethrough[derive(Serialize, Deserialize)]]
    struct Outer {
        field:

        #[serde(transparent)]
        struct Transparent {
            inner: struct Inner {
                name: String,
            }
        }
    }
}

fn main() {
    println!("Hello, world!");
}

[jcaesar]

Thanks for the PR. Can I ask you to make sure that it passes cargo test and cargo fmt -- --check? (If not, no problem, I can take care of that.)

[Luctins]

no problem, will do

[Luctins]

Ive messed around for a bit trying to make this work, and this seems to be a ok compromise.

It inserts non derive attributes after existing ones and inserts derive attributes before the existing attributes.

I'm not sure this is the most optimal way to do it though, as it creates 2 vectors each time.

[jcaesar]

This crate already allocates all over the place, no need to worry about a few more allocations. I do worry about the order though. Anyway.

Would it help you if I did a release with this quickly? (e.g. because you want to publish a crate that depends on this one to crates.io)

[Luctins]

Would it help you if I did a release with this quickly? (e.g. because you want to publish a crate that depends on this one to crates.io)

yes, please!
I currently use this crate for a project that is due to ship soon. It would be best to have all the dependencies on crates.io if possible.

Thanks a lot.