Add some regression tests for #44454

Signed-off-by: Yuki Okushi <[email protected]>

Author: JohnTitor

src/test/ui/traits/object/issue-44454-1.rs

@@ -0,0 +1,22 @@
+// Taken from https://github.com/rust-lang/rust/issues/44454#issue-256435333
+
+trait Animal<X>: 'static {}
+
+fn foo<Y, X>()
+where
+    Y: Animal<X> + ?Sized,
+{
+    // `Y` implements `Animal<X>` so `Y` is 'static.
+    baz::<Y>()
+}
+
+fn bar<'a>(_arg: &'a i32) {
+    foo::<dyn Animal<&'a i32>, &'a i32>() //~ ERROR: lifetime may not live long enough
+}
+
+fn baz<T: 'static + ?Sized>() {}
+
+fn main() {
+    let a = 5;
+    bar(&a);
+}

src/test/ui/traits/object/issue-44454-1.stderr

@@ -0,0 +1,10 @@
+error: lifetime may not live long enough
+  --> $DIR/issue-44454-1.rs:14:5
+   |
+LL | fn bar<'a>(_arg: &'a i32) {
+   |        -- lifetime `'a` defined here
+LL |     foo::<dyn Animal<&'a i32>, &'a i32>()
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ requires that `'a` must outlive `'static`
+
+error: aborting due to previous error
+

src/test/ui/traits/object/issue-44454-2.rs

@@ -0,0 +1,22 @@
+// Taken from https://github.com/rust-lang/rust/issues/44454#issuecomment-1175925928
+
+trait Trait<ARG: 'static>: 'static {
+    type Assoc: AsRef<str>;
+}
+
+fn hr<T: ?Sized, ARG>(x: T::Assoc) -> Box<dyn AsRef<str> + 'static>
+where
+    T: Trait<ARG>
+{
+    Box::new(x)
+}
+
+fn extend_lt<'a>(x: &'a str) -> Box<dyn AsRef<str> + 'static> {
+    type DynTrait = dyn for<'a> Trait<&'a str, Assoc = &'a str>;
+    hr::<DynTrait, _>(x) //~ ERROR: borrowed data escapes outside of function
+}
+
+fn main() {
+    let extended = extend_lt(&String::from("hello"));
+    println!("{}", extended.as_ref().as_ref());
+}

src/test/ui/traits/object/issue-44454-2.stderr

@@ -0,0 +1,17 @@
+error[E0521]: borrowed data escapes outside of function
+  --> $DIR/issue-44454-2.rs:16:5
+   |
+LL | fn extend_lt<'a>(x: &'a str) -> Box<dyn AsRef<str> + 'static> {
+   |              --  - `x` is a reference that is only valid in the function body
+   |              |
+   |              lifetime `'a` defined here
+LL |     type DynTrait = dyn for<'a> Trait<&'a str, Assoc = &'a str>;
+LL |     hr::<DynTrait, _>(x)
+   |     ^^^^^^^^^^^^^^^^^^^^
+   |     |
+   |     `x` escapes the function body here
+   |     argument requires that `'a` must outlive `'static`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0521`.

src/test/ui/traits/object/issue-44454-3.rs

@@ -0,0 +1,33 @@
+// Taken from https://github.com/rust-lang/rust/issues/44454#issuecomment-1332781290
+
+use std::any::Any;
+
+trait Animal<X>: 'static {}
+
+trait Projector {
+    type Foo;
+}
+
+impl<X> Projector for dyn Animal<X> {
+    type Foo = X;
+}
+
+fn make_static<'a, T>(t: &'a T) -> &'static T {
+    let x: <dyn Animal<&'a T> as Projector>::Foo = t;
+    let any = generic::<dyn Animal<&'a T>, &'a T>(x);
+    //~^ ERROR: lifetime may not live long enough
+    any.downcast_ref::<&'static T>().unwrap()
+}
+
+fn generic<T: Projector + Animal<U> + ?Sized, U>(x: <T as Projector>::Foo) -> Box<dyn Any> {
+    make_static_any(x)
+}
+
+fn make_static_any<U: 'static>(u: U) -> Box<dyn Any> {
+    Box::new(u)
+}
+
+fn main() {
+    let a = make_static(&"salut".to_string());
+    println!("{}", *a);
+}

src/test/ui/traits/object/issue-44454-3.stderr

@@ -0,0 +1,11 @@
+error: lifetime may not live long enough
+  --> $DIR/issue-44454-3.rs:17:15
+   |
+LL | fn make_static<'a, T>(t: &'a T) -> &'static T {
+   |                -- lifetime `'a` defined here
+LL |     let x: <dyn Animal<&'a T> as Projector>::Foo = t;
+LL |     let any = generic::<dyn Animal<&'a T>, &'a T>(x);
+   |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ requires that `'a` must outlive `'static`
+
+error: aborting due to previous error
+