Unrolled build for #142200

Rollup merge of #142200 - Kivooeo:tf8, r=jieyouxu

`tests/ui`: A New Order [8/N]

Some `tests/ui/` housekeeping, to trim down number of tests directly under `tests/ui/`. Part of #133895.

Author: rust-timer

tests/ui/defaults-well-formedness.rs

@@ -2,4 +2,4 @@
 //@ compile-flags:-Zforce-unstable-if-unmarked
 
 #[deprecated] // should work even with -Zforce-unstable-if-unmarked
-fn main() { }
+fn main() {}

tests/ui/deprecation-in-force-unstable.rs renamed to tests/ui/deprecation/deprecated_main_function.rs

@@ -0,0 +1,23 @@
+//! Regression test for `#[derive(Debug)]` on enums with uninhabited variants.
+//!
+//! Ensures there are no special warnings about uninhabited types when deriving
+//! Debug on an enum with uninhabited variants, only standard unused warnings.
+//!
+//! Issue: https://github.com/rust-lang/rust/issues/38885
+
+//@ check-pass
+//@ compile-flags: -Wunused
+
+#[derive(Debug)]
+enum Void {}
+
+#[derive(Debug)]
+enum Foo {
+    Bar(#[allow(dead_code)] u8),
+    Void(Void), //~ WARN variant `Void` is never constructed
+}
+
+fn main() {
+    let x = Foo::Bar(42);
+    println!("{:?}", x);
+}

tests/ui/deref-rc.rs

@@ -1,5 +1,5 @@
 warning: variant `Void` is never constructed
-  --> $DIR/derive-uninhabited-enum-38885.rs:13:5
+  --> $DIR/derive-debug-uninhabited-enum.rs:17:5
    |
 LL | enum Foo {
    |      --- variant in this enum