needless_borrow suggesting the same fix as exists in code

[dessalines]

Lint name: needless_borrow

I tried this code, which is getting a connection from a deadpool database pool:

let join = CommunityModerator::join(&&context.pool.get().await?, &community_moderator_form);

I expected to see this happen: No clippy warnings.

Instead, this happened:

error: this expression borrows a reference (`&deadpool_diesel::connection::Connection<diesel::pg::connection::PgConnection>`) that is immed
iately dereferenced by the compiler
   --> crates/api_crud/src/user/create.rs:195:43
    |
195 |       let join = CommunityModerator::join(&&context.pool.get().await?, &community_moderator_form);
    |                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: change this to: `&&context.pool.get().await?`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrow

Its suggesting a fix that's the same as the error

Meta

• cargo clippy -V: clippy 0.1.56 (ae90dcf 2021-08-09)
• rustc -Vv:

rustc 1.56.0-nightly (ae90dcf02 2021-08-09)
binary: rustc
commit-hash: ae90dcf0207c57c3034f00b07048d63f8b2363c8
commit-date: 2021-08-09
host: x86_64-unknown-linux-gnu
release: 1.56.0-nightly
LLVM version: 12.0.1

[DevinR528]

I'm not able to reproduce this?

warning: this expression borrows a reference (`&diesel::r2d2::PooledConnection<diesel::r2d2::ConnectionManager<diesel::PgConnection>>`) that is immediately dereferenced by the compiler
   --> crates/apub/src/fetcher/community.rs:108:43
    |
108 |       let join = CommunityModerator::join(&&context.pool.get()?, &community_moderator_form);
    |                                           ^^^^^^^^^^^^^^^^^^^^^ help: change this to: `&context.pool.get()?`
    |
    = note: `#[warn(clippy::needless_borrow)]` on by default
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrow

warning: `lemmy_apub` (lib) generated 2 warnings

The only difference is it's not async but I'm not sure if that's a problem? I could not set something up to reproduce in Clippys UI tests so I checked the source and couldn't get that to fail with clippy 0.1.56 (ad02dc4 2021-08-26)

[dessalines]

One piece of context I can give, is that in order to get a usable &PgConnection from deadpools Connection<PgConnection>, you have to dereference it twice:

    let test : Connection<PgConnection> = context.pool.get().await?;
    let test2: &PgConnection = &&test;

[DevinR528]

Hmm, yeah, although it should either fail the same way for &&Arc<Arc<Thing>> as an argument to an fn that takes &Thing right?