stabalize infer outlives requirements (RFC 2093).

Co-authored-by: nikomatsakis

src/test/ui/issues/issue-37323.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// compile-pass
+
 #![feature(rustc_attrs)]
 #![allow(warnings)]
 
@@ -17,7 +19,6 @@ struct Point {
 
 struct NestedA<'a, 'b> {
     x: &'a NestedB<'b>
-    //~^ ERROR E0491
 }
 
 struct NestedB<'a> {

src/test/ui/issues/issue-37323.stderr

@@ -1,20 +0,0 @@
-error[E0491]: in type `&'a NestedB<'b>`, reference has a longer lifetime than the data it references
-  --> $DIR/issue-37323.rs:19:5
-   |
-LL |     x: &'a NestedB<'b>
-   |     ^^^^^^^^^^^^^^^^^^
-   |
-note: the pointer is valid for the lifetime 'a as defined on the struct at 18:16
-  --> $DIR/issue-37323.rs:18:16
-   |
-LL | struct NestedA<'a, 'b> {
-   |                ^^
-note: but the referenced data is only valid for the lifetime 'b as defined on the struct at 18:20
-  --> $DIR/issue-37323.rs:18:20
-   |
-LL | struct NestedA<'a, 'b> {
-   |                    ^^
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0491`.