From 3f21ebcb7a7cdb11c29a5f47718ad6a5b0e12fdd Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Thu, 13 Mar 2025 18:31:34 -0300
Subject: [PATCH] Test interaction between RFC 2229 migration and use closures

---
 .../closure/rfc2229-migration.fixed           | 26 ++++++++++++++++++
 .../closure/rfc2229-migration.rs              | 25 +++++++++++++++++
 .../closure/rfc2229-migration.stderr          | 27 +++++++++++++++++++
 3 files changed, 78 insertions(+)
 create mode 100644 tests/ui/ergonomic-clones/closure/rfc2229-migration.fixed
 create mode 100644 tests/ui/ergonomic-clones/closure/rfc2229-migration.rs
 create mode 100644 tests/ui/ergonomic-clones/closure/rfc2229-migration.stderr

diff --git a/tests/ui/ergonomic-clones/closure/rfc2229-migration.fixed b/tests/ui/ergonomic-clones/closure/rfc2229-migration.fixed
new file mode 100644
index 0000000000000..fa83b53526a85
--- /dev/null
+++ b/tests/ui/ergonomic-clones/closure/rfc2229-migration.fixed
@@ -0,0 +1,26 @@
+//@ run-rustfix
+//@ edition:2018
+//@ check-pass
+#![feature(ergonomic_clones)]
+#![warn(rust_2021_compatibility)]
+#![allow(incomplete_features)]
+
+#[derive(Debug)]
+struct Foo(i32);
+impl Drop for Foo {
+    fn drop(&mut self) {
+        println!("{:?} dropped", self.0);
+    }
+}
+
+fn main() {
+    let a = (Foo(0), Foo(1));
+    let f = use || {
+        let _ = &a;
+        //~^ HELP: add a dummy
+        //~| WARNING: drop order
+        let x = a.0;
+        println!("{:?}", x);
+    };
+    f();
+}
diff --git a/tests/ui/ergonomic-clones/closure/rfc2229-migration.rs b/tests/ui/ergonomic-clones/closure/rfc2229-migration.rs
new file mode 100644
index 0000000000000..4070e5c35a441
--- /dev/null
+++ b/tests/ui/ergonomic-clones/closure/rfc2229-migration.rs
@@ -0,0 +1,25 @@
+//@ run-rustfix
+//@ edition:2018
+//@ check-pass
+#![feature(ergonomic_clones)]
+#![warn(rust_2021_compatibility)]
+#![allow(incomplete_features)]
+
+#[derive(Debug)]
+struct Foo(i32);
+impl Drop for Foo {
+    fn drop(&mut self) {
+        println!("{:?} dropped", self.0);
+    }
+}
+
+fn main() {
+    let a = (Foo(0), Foo(1));
+    let f = use || {
+        //~^ HELP: add a dummy
+        //~| WARNING: drop order
+        let x = a.0;
+        println!("{:?}", x);
+    };
+    f();
+}
diff --git a/tests/ui/ergonomic-clones/closure/rfc2229-migration.stderr b/tests/ui/ergonomic-clones/closure/rfc2229-migration.stderr
new file mode 100644
index 0000000000000..b980be6cb86bf
--- /dev/null
+++ b/tests/ui/ergonomic-clones/closure/rfc2229-migration.stderr
@@ -0,0 +1,27 @@
+warning: changes to closure capture in Rust 2021 will affect drop order
+  --> $DIR/rfc2229-migration.rs:18:13
+   |
+LL |     let f = use || {
+   |             ^^^^^^
+...
+LL |         let x = a.0;
+   |                 --- in Rust 2018, this closure captures all of `a`, but in Rust 2021, it will only capture `a.0`
+...
+LL | }
+   | - in Rust 2018, `a` is dropped here, but in Rust 2021, only `a.0` will be dropped here as part of the closure
+   |
+   = 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
+  --> $DIR/rfc2229-migration.rs:5:9
+   |
+LL | #![warn(rust_2021_compatibility)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^
+   = note: `#[warn(rust_2021_incompatible_closure_captures)]` implied by `#[warn(rust_2021_compatibility)]`
+help: add a dummy let to cause `a` to be fully captured
+   |
+LL ~     let f = use || {
+LL +         let _ = &a;
+   |
+
+warning: 1 warning emitted
+