From 6f968782fdbe806007b4adbe98d362a96c9981cf Mon Sep 17 00:00:00 2001
From: Jonathan Brouwer <jonathantbrouwer@gmail.com>
Date: Fri, 17 Apr 2026 12:37:58 +0200
Subject: [PATCH] Add regression tests

---
 tests/ui/attributes/attr-order-deprecated.rs  | 11 ++++++
 .../attributes/attr-order-deprecated.stderr   | 22 ++++++++++++
 tests/ui/attributes/attr-order-must-use.rs    | 19 +++++++++++
 .../ui/attributes/attr-order-must-use.stderr  | 34 +++++++++++++++++++
 4 files changed, 86 insertions(+)
 create mode 100644 tests/ui/attributes/attr-order-deprecated.rs
 create mode 100644 tests/ui/attributes/attr-order-deprecated.stderr
 create mode 100644 tests/ui/attributes/attr-order-must-use.rs
 create mode 100644 tests/ui/attributes/attr-order-must-use.stderr

diff --git a/tests/ui/attributes/attr-order-deprecated.rs b/tests/ui/attributes/attr-order-deprecated.rs
new file mode 100644
index 000000000000..606e714819b5
--- /dev/null
+++ b/tests/ui/attributes/attr-order-deprecated.rs
@@ -0,0 +1,11 @@
+#[deprecated = "AAA"]
+//~^ NOTE also specified here
+#[deprecated = "BBB"]
+//~^ ERROR multiple `deprecated` attributes
+fn deprecated() { }
+
+fn main() {
+    deprecated();
+    //~^ WARN use of deprecated function `deprecated`: AAA [deprecated]
+    //~| NOTE `#[warn(deprecated)]` on by default
+}
diff --git a/tests/ui/attributes/attr-order-deprecated.stderr b/tests/ui/attributes/attr-order-deprecated.stderr
new file mode 100644
index 000000000000..41e26bec761e
--- /dev/null
+++ b/tests/ui/attributes/attr-order-deprecated.stderr
@@ -0,0 +1,22 @@
+error: multiple `deprecated` attributes
+  --> $DIR/attr-order-deprecated.rs:3:1
+   |
+LL | #[deprecated = "BBB"]
+   | ^^^^^^^^^^^^^^^^^^^^^ help: remove this attribute
+   |
+note: attribute also specified here
+  --> $DIR/attr-order-deprecated.rs:1:1
+   |
+LL | #[deprecated = "AAA"]
+   | ^^^^^^^^^^^^^^^^^^^^^
+
+warning: use of deprecated function `deprecated`: AAA
+  --> $DIR/attr-order-deprecated.rs:8:5
+   |
+LL |     deprecated();
+   |     ^^^^^^^^^^
+   |
+   = note: `#[warn(deprecated)]` on by default
+
+error: aborting due to 1 previous error; 1 warning emitted
+
diff --git a/tests/ui/attributes/attr-order-must-use.rs b/tests/ui/attributes/attr-order-must-use.rs
new file mode 100644
index 000000000000..36ffe9d5ed70
--- /dev/null
+++ b/tests/ui/attributes/attr-order-must-use.rs
@@ -0,0 +1,19 @@
+#![deny(unused)]
+//~^ NOTE lint level is defined here
+
+#[must_use = "AAA"]
+//~^ NOTE also specified here
+#[must_use = "BBB"]
+//~^ ERROR unused attribute
+//~| WARN previously accepted
+//~| NOTE `#[deny(unused_attributes)]` implied by `#[deny(unused)]`
+fn must_use() -> usize {
+    0
+}
+
+fn main() {
+    must_use();
+    //~^ ERROR unused return value of `must_use` that must be used
+    //~| NOTE AAA
+    //~| NOTE `#[deny(unused_must_use)]` implied by `#[deny(unused)]`
+}
diff --git a/tests/ui/attributes/attr-order-must-use.stderr b/tests/ui/attributes/attr-order-must-use.stderr
new file mode 100644
index 000000000000..18b581162301
--- /dev/null
+++ b/tests/ui/attributes/attr-order-must-use.stderr
@@ -0,0 +1,34 @@
+error: unused attribute
+  --> $DIR/attr-order-must-use.rs:6:1
+   |
+LL | #[must_use = "BBB"]
+   | ^^^^^^^^^^^^^^^^^^^ help: remove this attribute
+   |
+note: attribute also specified here
+  --> $DIR/attr-order-must-use.rs:4:1
+   |
+LL | #[must_use = "AAA"]
+   | ^^^^^^^^^^^^^^^^^^^
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+note: the lint level is defined here
+  --> $DIR/attr-order-must-use.rs:1:9
+   |
+LL | #![deny(unused)]
+   |         ^^^^^^
+   = note: `#[deny(unused_attributes)]` implied by `#[deny(unused)]`
+
+error: unused return value of `must_use` that must be used
+  --> $DIR/attr-order-must-use.rs:15:5
+   |
+LL |     must_use();
+   |     ^^^^^^^^^^
+   |
+   = note: AAA
+   = note: `#[deny(unused_must_use)]` implied by `#[deny(unused)]`
+help: use `let _ = ...` to ignore the resulting value
+   |
+LL |     let _ = must_use();
+   |     +++++++
+
+error: aborting due to 2 previous errors
+