Add regression test for #127424

tests/ui/const-generics/generic_const_exprs/const-generics-closure.rs

@@ -0,0 +1,13 @@
+// Regression test for issue #127424
+
+fn bar() -> impl Into<
+    [u8; {
+        //~^ ERROR mismatched types [E0308]
+        let _ = for<'a, 'b> |x: &'a &'a Vec<&'b u32>, b: bool| -> &'a Vec<&'b u32> { *x };
+        //~^ ERROR `for<...>` binders for closures are experimental [E0658]
+    }],
+> {
+    [89]
+}
+
+fn main() {}

tests/ui/const-generics/generic_const_exprs/const-generics-closure.stderr

@@ -0,0 +1,26 @@
+error[E0658]: `for<...>` binders for closures are experimental
+  --> $DIR/const-generics-closure.rs:6:17
+   |
+LL |         let _ = for<'a, 'b> |x: &'a &'a Vec<&'b u32>, b: bool| -> &'a Vec<&'b u32> { *x };
+   |                 ^^^^^^^^^^^
+   |
+   = note: see issue #97362 <https://github.com/rust-lang/rust/issues/97362> for more information
+   = help: add `#![feature(closure_lifetime_binder)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = help: consider removing `for<...>`
+
+error[E0308]: mismatched types
+  --> $DIR/const-generics-closure.rs:4:10
+   |
+LL |       [u8; {
+   |  __________^
+LL | |
+LL | |         let _ = for<'a, 'b> |x: &'a &'a Vec<&'b u32>, b: bool| -> &'a Vec<&'b u32> { *x };
+LL | |
+LL | |     }],
+   | |_____^ expected `usize`, found `()`
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0308, E0658.
+For more information about an error, try `rustc --explain E0308`.