use a minimized example

src/test/ui/regions/do-not-suggest-adding-bound-to-opaque-type.rs

@@ -1,29 +1,12 @@
-#![feature(allocator_api)]
+pub trait T {}
 
-use std::{
-    alloc::{AllocError, Allocator, Layout},
-    ptr::NonNull,
-};
+struct S<'a>(&'a ());
 
-struct GhostBump;
+impl<'a> T for S<'a> {}
 
-unsafe impl Allocator for &GhostBump {
-    fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError> {
-        todo!()
-    }
-
-    unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout) {
-        todo!()
-    }
-}
-
-fn foo() -> impl Iterator<Item = usize> {
-    let arena = GhostBump;
-    let mut vec = Vec::new_in(&arena); //~ ERROR `arena` does not live long enough
-    vec.push(1);
-    vec.push(2);
-    vec.push(3);
-    vec.into_iter()
+fn foo() -> impl T {
+    let x = ();
+    S(&x) //~ ERROR `x` does not live long enough
 }
 
 fn main() {}

src/test/ui/regions/do-not-suggest-adding-bound-to-opaque-type.stderr

@@ -1,13 +1,13 @@
-error[E0597]: `arena` does not live long enough
-  --> $DIR/do-not-suggest-adding-bound-to-opaque-type.rs:22:31
+error[E0597]: `x` does not live long enough
+  --> $DIR/do-not-suggest-adding-bound-to-opaque-type.rs:9:7
    |
-LL |     let mut vec = Vec::new_in(&arena);
-   |                               ^^^^^^ borrowed value does not live long enough
-...
-LL |     vec.into_iter()
-   |     --------------- opaque type requires that `arena` is borrowed for `'static`
+LL |     S(&x)
+   |     --^^-
+   |     | |
+   |     | borrowed value does not live long enough
+   |     opaque type requires that `x` is borrowed for `'static`
 LL | }
-   | - `arena` dropped here while still borrowed
+   | - `x` dropped here while still borrowed
 
 error: aborting due to previous error