1 files changed, 41 insertions, 0 deletions
diff --git a/tests/ui/deriving/multiple-defaults.rs b/tests/ui/deriving/multiple-defaults.rs
new file mode 100644
index 000000000..2024a5520
--- /dev/null
+++ b/tests/ui/deriving/multiple-defaults.rs
@@ -0,0 +1,41 @@
+// compile-flags: --crate-type=lib
+
+// When we get multiple `#[default]` variants, we emit several tool-only suggestions
+// to remove all except one of the `#[default]`s.
+
+#[derive(Default)] //~ ERROR multiple declared defaults
+enum A {
+    #[default] //~ HELP make `B` default
+    #[default] //~ HELP make `A` default
+    A,
+    #[default] // also "HELP make `A` default", but compiletest can't handle multispans
+    B,
+}
+
+// Originally, we took each defaulted variant and emitted the suggestion for every variant
+// with a different identifier, causing an ICE when multiple variants have the same identifier:
+// https://github.com/rust-lang/rust/pull/105106
+#[derive(Default)] //~ ERROR multiple declared defaults
+enum E {
+    #[default] //~ HELP make `A` default
+    A,
+    #[default] //~ HELP make `A` default
+    A, //~ ERROR defined multiple times
+}
+
+// Then, we took each defaulted variant and emitted the suggestion for every variant
+// with a different span, causing an ICE when multiple variants have the same span:
+// https://github.com/rust-lang/rust/issues/118119
+macro_rules! m {
+    { $($id:ident)* } => {
+        #[derive(Default)] //~ ERROR multiple declared defaults
+        enum F {
+            $(
+                #[default]
+                $id,
+            )*
+        }
+    }
+}
+
+m! { A B }