From 80a9c2c8af3073d62c840ca808107b80378ded6a Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Sun, 22 Jan 2023 13:51:01 -0800
Subject: [PATCH 1/2] Add regression test for issue 234

Currently fails to compile:

    error: changes to closure capture in Rust 2021 will affect drop order
        --> tests/test.rs:1549:59
         |
    1549 |         async fn f(Tuple(_, _int): Tuple<Droppable, i32>) {}
         |                    --------------                         ^-
         |                    |                                       |
         |                    |                                       in Rust 2018, `__arg0` is dropped here, but in Rust 2021, only `__arg0.1` will be dropped here as part of the closure
         |                    in Rust 2018, this closure captures all of `__arg0`, but in Rust 2021, it will only capture `__arg0.1`
         |
         = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/disjoint-capture-in-closures.html>
    note: the lint level is defined here
        --> tests/test.rs:5:9
         |
    5    | #![deny(rust_2021_compatibility)]
         |         ^^^^^^^^^^^^^^^^^^^^^^^
         = note: `#[deny(rust_2021_incompatible_closure_captures)]` implied by `#[deny(rust_2021_compatibility)]`
    help: add a dummy let to cause `__arg0` to be fully captured
         |
    1549 |         async fn f(Tuple(_, _int): Tuple<Droppable, i32>) { let _ = &__arg0;}
         |                                                             ++++++++++++++++

    error: changes to closure capture in Rust 2021 will affect drop order
        --> tests/test.rs:1556:66
         |
    1556 |         async fn f(Tuple { 1: _int, .. }: Tuple<Droppable, i32>) {}
         |                    ---------------------                         ^-
         |                    |                                              |
         |                    |                                              in Rust 2018, `__arg0` is dropped here, but in Rust 2021, only `__arg0.1` will be dropped here as part of the closure
         |                    in Rust 2018, this closure captures all of `__arg0`, but in Rust 2021, it will only capture `__arg0.1`
         |
         = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/disjoint-capture-in-closures.html>
    help: add a dummy let to cause `__arg0` to be fully captured
         |
    1556 |         async fn f(Tuple { 1: _int, .. }: Tuple<Droppable, i32>) { let _ = &__arg0;}
         |                                                                    ++++++++++++++++
---
 tests/test.rs | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/tests/test.rs b/tests/test.rs
index 211387a..2d7dc65 100644
--- a/tests/test.rs
+++ b/tests/test.rs
@@ -2,6 +2,7 @@
     async_trait_nightly_testing,
     feature(min_specialization, type_alias_impl_trait)
 )]
+#![deny(rust_2021_compatibility)]
 #![allow(
     clippy::let_unit_value,
     clippy::missing_panics_doc,
@@ -1523,3 +1524,35 @@ pub mod issue232 {
         async fn take_ref(&self, (_a, _b, _c): &(T, T, T)) {}
     }
 }
+
+// https://github.com/dtolnay/async-trait/issues/234
+pub mod issue234 {
+    use async_trait::async_trait;
+
+    pub struct Droppable;
+
+    impl Drop for Droppable {
+        fn drop(&mut self) {}
+    }
+
+    pub struct Tuple<T, U>(T, U);
+
+    #[async_trait]
+    pub trait Trait {
+        async fn f(arg: Tuple<Droppable, i32>);
+    }
+
+    pub struct UnderscorePattern;
+
+    #[async_trait]
+    impl Trait for UnderscorePattern {
+        async fn f(Tuple(_, _int): Tuple<Droppable, i32>) {}
+    }
+
+    pub struct DotDotPattern;
+
+    #[async_trait]
+    impl Trait for DotDotPattern {
+        async fn f(Tuple { 1: _int, .. }: Tuple<Droppable, i32>) {}
+    }
+}

From 1c2e90a9846fa386d8a28415eaef09103c663106 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Sun, 22 Jan 2023 13:52:02 -0800
Subject: [PATCH 2/2] Make expansion of nested _ and .. patterns edition
 independent

---
 src/expand.rs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/expand.rs b/src/expand.rs
index 7747e68..c2cfacb 100644
--- a/src/expand.rs
+++ b/src/expand.rs
@@ -403,7 +403,10 @@ fn transform_block(context: Context, sig: &mut Signature, block: &mut Block) {
                     } else {
                         quote! {
                             #(#attrs)*
-                            let #pat = #ident;
+                            let #pat = {
+                                let #ident = #ident;
+                                #ident
+                            };
                         }
                     }
                 }