run borrowck tests on BIDs and emit tail-expr-drop-order lints for

potential violations

2 files changed, 77 insertions, 0 deletions

diff --git a/tests/ui/drop/lint-tail-expr-drop-order-borrowck.rs b/tests/ui/drop/lint-tail-expr-drop-order-borrowck.rs
new file mode 100644
index 00000000000..1bd5655d7fe
--- /dev/null
+++ b/tests/ui/drop/lint-tail-expr-drop-order-borrowck.rs
@@ -0,0 +1,37 @@
+// Edition 2024 lint for change in drop order at tail expression
+// This lint is to capture potential borrow-checking errors
+// due to implementation of RFC 3606 <https://github.com/rust-lang/rfcs/pull/3606>
+//@ edition: 2021
+
+#![deny(tail_expr_drop_order)] //~ NOTE: the lint level is defined here
+
+fn should_lint_with_potential_borrowck_err() {
+    let _ = { String::new().as_str() }.len();
+    //~^ ERROR: a temporary value will be dropped here
+    //~| WARN: this changes meaning in Rust 2024
+    //~| NOTE: consider using a `let` binding
+    //~| NOTE: for more information, see
+}
+
+fn should_lint_with_unsafe_block() {
+    fn f(_: usize) {}
+    f(unsafe { String::new().as_str() }.len());
+    //~^ ERROR: a temporary value will be dropped here
+    //~| WARN: this changes meaning in Rust 2024
+    //~| NOTE: consider using a `let` binding
+    //~| NOTE: for more information, see
+}
+
+#[rustfmt::skip]
+fn should_lint_with_big_block() {
+    fn f<T>(_: T) {}
+    f({
+        &mut || 0
+        //~^ ERROR: a temporary value will be dropped here
+        //~| WARN: this changes meaning in Rust 2024
+        //~| NOTE: consider using a `let` binding
+        //~| NOTE: for more information, see
+    })
+}
+
+fn main() {}
diff --git a/tests/ui/drop/lint-tail-expr-drop-order-borrowck.stderr b/tests/ui/drop/lint-tail-expr-drop-order-borrowck.stderr
new file mode 100644
index 00000000000..98ef0547c90
--- /dev/null
+++ b/tests/ui/drop/lint-tail-expr-drop-order-borrowck.stderr
@@ -0,0 +1,40 @@
+error: a temporary value will be dropped here before the execution exits the block in Edition 2024, which will raise borrow checking error
+  --> $DIR/lint-tail-expr-drop-order-borrowck.rs:9:36
+   |
+LL |     let _ = { String::new().as_str() }.len();
+   |               -------------        ^
+   |               |
+   |               consider using a `let` binding to create a longer lived value; or replacing the `{ .. }` block with curly brackets `( .. )`; or folding the rest of the expression into the surrounding `unsafe { .. }`
+   |
+   = warning: this changes meaning in Rust 2024
+   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2024/temporary-tail-expr-scope.html>
+note: the lint level is defined here
+  --> $DIR/lint-tail-expr-drop-order-borrowck.rs:6:9
+   |
+LL | #![deny(tail_expr_drop_order)]
+   |         ^^^^^^^^^^^^^^^^^^^^
+
+error: a temporary value will be dropped here before the execution exits the block in Edition 2024, which will raise borrow checking error
+  --> $DIR/lint-tail-expr-drop-order-borrowck.rs:18:37
+   |
+LL |     f(unsafe { String::new().as_str() }.len());
+   |                -------------        ^
+   |                |
+   |                consider using a `let` binding to create a longer lived value; or replacing the `{ .. }` block with curly brackets `( .. )`; or folding the rest of the expression into the surrounding `unsafe { .. }`
+   |
+   = warning: this changes meaning in Rust 2024
+   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2024/temporary-tail-expr-scope.html>
+
+error: a temporary value will be dropped here before the execution exits the block in Edition 2024, which will raise borrow checking error
+  --> $DIR/lint-tail-expr-drop-order-borrowck.rs:29:17
+   |
+LL |         &mut || 0
+   |         --------^
+   |         |
+   |         consider using a `let` binding to create a longer lived value; or replacing the `{ .. }` block with curly brackets `( .. )`; or folding the rest of the expression into the surrounding `unsafe { .. }`
+   |
+   = warning: this changes meaning in Rust 2024
+   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2024/temporary-tail-expr-scope.html>
+
+error: aborting due to 3 previous errors
+