add a test for shortening super let binding lifetimes

Author: dianne

tests/ui/lifetimes/lint-macro-extended-temporary-scopes/extended-super-let-bindings.rs

@@ -0,0 +1,11 @@
+//! Some temporaries are implemented as local variables bound with `super let`. These can be
+//! lifetime-extended, and as such are subject to shortening after #145838.
+//@ edition: 2024
+//@ check-pass
+
+fn main() {
+    // The `()` argument to the inner `format_args!` is promoted, but the lifetimes of the internal
+    // `super let` temporaries in its expansion shorten, making this an error in Rust 1.92.
+    println!("{:?}{}", (), { format_args!("{:?}", ()) });
+    // TODO: warn
+}