Add variance-related information to lifetime error messages

[rust.git] / src / test / ui / regions / region-multiple-lifetime-bounds-on-fns-where-clause.nll.stderr

diff --git a/src/test/ui/regions/region-multiple-lifetime-bounds-on-fns-where-clause.nll.stderr b/src/test/ui/regions/region-multiple-lifetime-bounds-on-fns-where-clause.nll.stderr
index a28f7aa3e08ca73b14f95ae8b84d032875f333cd..a9cf128bb621a4bdec7167e1dee1573b058c6597 100644 (file)
--- a/src/test/ui/regions/region-multiple-lifetime-bounds-on-fns-where-clause.nll.stderr
+++ b/src/test/ui/regions/region-multiple-lifetime-bounds-on-fns-where-clause.nll.stderr
@@ -23,6 +23,9 @@ LL |     a(x, y, z);
    |     ^^^^^^^^^^ argument requires that `'b` must outlive `'a`
    |
    = help: consider adding the following bound: `'b: 'a`
+   = note: requirement occurs because of a mutable reference to &isize
+   = note: mutable references are invariant over their type parameter
+   = help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
 
 error: higher-ranked subtype error
   --> $DIR/region-multiple-lifetime-bounds-on-fns-where-clause.rs:22:12