add test for duplicate warning on used deprecated unit structs

Co-authored-by: Waffle Lapkin <[email protected]>

Author: jdonszelmann

tests/ui/deprecation/unit_and_tuple_struct.rs

@@ -0,0 +1,28 @@
+#![deny(deprecated)]
+#![allow(unused_imports)]
+
+#[deprecated]
+pub mod a {
+    pub struct Foo;
+    pub struct Bar();
+    pub struct Baz {}
+}
+
+
+use a::Foo;
+//~^ ERROR use of deprecated struct `a::Foo`
+//~| ERROR use of deprecated unit struct `a::Foo`
+use a::Bar;
+//~^ ERROR use of deprecated struct `a::Bar`
+//~| ERROR use of deprecated tuple struct `a::Bar`
+use a::Baz;
+//~^ ERROR use of deprecated struct `a::Baz`
+
+fn main() {
+  a::Foo;
+  //~^ ERROR use of deprecated unit struct `a::Foo`
+  a::Bar();
+  //~^ ERROR use of deprecated tuple struct `a::Bar`
+  a::Baz {};
+  //~^ ERROR use of deprecated struct `a::Baz`
+}

tests/ui/deprecation/unit_and_tuple_struct.stderr

@@ -0,0 +1,56 @@
+error: use of deprecated struct `a::Foo`
+  --> $DIR/unit_and_tuple_struct.rs:12:8
+   |
+LL | use a::Foo;
+   |        ^^^
+   |
+note: the lint level is defined here
+  --> $DIR/unit_and_tuple_struct.rs:1:9
+   |
+LL | #![deny(deprecated)]
+   |         ^^^^^^^^^^
+
+error: use of deprecated unit struct `a::Foo`
+  --> $DIR/unit_and_tuple_struct.rs:12:8
+   |
+LL | use a::Foo;
+   |        ^^^
+
+error: use of deprecated struct `a::Bar`
+  --> $DIR/unit_and_tuple_struct.rs:15:8
+   |
+LL | use a::Bar;
+   |        ^^^
+
+error: use of deprecated tuple struct `a::Bar`
+  --> $DIR/unit_and_tuple_struct.rs:15:8
+   |
+LL | use a::Bar;
+   |        ^^^
+
+error: use of deprecated struct `a::Baz`
+  --> $DIR/unit_and_tuple_struct.rs:18:8
+   |
+LL | use a::Baz;
+   |        ^^^
+
+error: use of deprecated unit struct `a::Foo`
+  --> $DIR/unit_and_tuple_struct.rs:22:6
+   |
+LL |   a::Foo;
+   |      ^^^
+
+error: use of deprecated tuple struct `a::Bar`
+  --> $DIR/unit_and_tuple_struct.rs:24:6
+   |
+LL |   a::Bar();
+   |      ^^^
+
+error: use of deprecated struct `a::Baz`
+  --> $DIR/unit_and_tuple_struct.rs:26:6
+   |
+LL |   a::Baz {};
+   |      ^^^
+
+error: aborting due to 8 previous errors
+