Add rustdonc-json regression test for #98009

Author: GuillaumeGomez

src/test/rustdoc-json/output_generics.rs

@@ -0,0 +1,38 @@
+// compile-flags: --document-private-items --document-hidden-items
+
+// This is a regression test for #98009.
+
+// @has output_generics.json
+// @has - "$.index[*][?(@.name=='this_compiles')]"
+// @has - "$.index[*][?(@.name=='this_does_not')]"
+// @has - "$.index[*][?(@.name=='Events')]"
+// @has - "$.index[*][?(@.name=='Other')]"
+// @has - "$.index[*][?(@.name=='Trait')]"
+
+struct Events<R>(R);
+
+struct Other;
+
+pub trait Trait<T> {
+    fn handle(value: T) -> Self;
+}
+
+impl<T, U> Trait<U> for T where T: From<U> {
+    fn handle(_: U) -> Self { unimplemented!() }
+}
+
+impl<'a, R> Trait<&'a mut Events<R>> for Other {
+    fn handle(_: &'a mut Events<R>) -> Self { unimplemented!() }
+}
+
+fn this_compiles<'a, R>(value: &'a mut Events<R>) {
+    for _ in 0..3 {
+        Other::handle(&mut *value);
+    }
+}
+
+fn this_does_not<'a, R>(value: &'a mut Events<R>) {
+    for _ in 0..3 {
+        Other::handle(value);
+    }
+}