Merge #6921

6921: Higher-ranked trait bounds for where clauses r=flodiebold a=Veykril

There is a slight problem with this which is also noted in a FIXME now but `LifetimeParameters` of these ForLifetime where clauses allocate the lifetimes in the corresponding arena as if they were lifetimes of the item itself and not just the clause they belong to. I wasn't entirely sure what I could do about this but given nothing really uses lifetimes like that currently I figured it might be fine? Open to suggestions for that problem.

Co-authored-by: Lukas Wirth <lukastw97@gmail.com>

crates/ide/src/goto_definition.rs

@@ -1077,4 +1077,32 @@ fn foo<'foobar>(_: &'foobar ()) {
 }"#,
         )
     }
+
+    #[test]
+    #[ignore] // requires the HIR to somehow track these hrtb lifetimes
+    fn goto_lifetime_hrtb() {
+        check(
+            r#"trait Foo<T> {}
+fn foo<T>() where for<'a> T: Foo<&'a<|> (u8, u16)>, {}
+                    //^^
+"#,
+        );
+        check(
+            r#"trait Foo<T> {}
+fn foo<T>() where for<'a<|>> T: Foo<&'a (u8, u16)>, {}
+                    //^^
+"#,
+        );
+    }
+
+    #[test]
+    #[ignore] // requires ForTypes to be implemented
+    fn goto_lifetime_hrtb_for_type() {
+        check(
+            r#"trait Foo<T> {}
+fn foo<T>() where T: for<'a> Foo<&'a<|> (u8, u16)>, {}
+                       //^^
+"#,
+        );
+    }
 }