Add an attribute to be able to configure the limit

src/test/ui/async-await/large_moves.rs

@@ -1,4 +1,6 @@
 #![deny(large_assignments)]
+#![feature(large_assignments)]
+#![move_size_limit = "1000"]
 // build-fail
 
 // edition:2018

src/test/ui/async-await/large_moves.stderr

@@ -1,5 +1,5 @@
 error: moving 10024 bytes
-  --> $DIR/large_moves.rs:7:13
+  --> $DIR/large_moves.rs:9:13
    |
 LL |       let x = async {
    |  _____________^
@@ -17,19 +17,19 @@ LL | #![deny(large_assignments)]
    |         ^^^^^^^^^^^^^^^^^
 
 error: moving 10024 bytes
-  --> $DIR/large_moves.rs:13:14
+  --> $DIR/large_moves.rs:15:14
    |
 LL |     let z = (x, 42);
    |              ^ value moved from here
 
 error: moving 10024 bytes
-  --> $DIR/large_moves.rs:13:13
+  --> $DIR/large_moves.rs:15:13
    |
 LL |     let z = (x, 42);
    |             ^^^^^^^ value moved from here
 
 error: moving 10024 bytes
-  --> $DIR/large_moves.rs:15:13
+  --> $DIR/large_moves.rs:17:13
    |
 LL |     let a = z.0;
    |             ^^^ value moved from here

src/test/ui/feature-gates/feature-gate-large-assignments.rs

@@ -0,0 +1,5 @@
+// check that `move_size_limit is feature-gated
+
+#![move_size_limit = "42"] //~ ERROR the `#[move_size_limit]` attribute is an experimental feature
+
+fn main() {}

src/test/ui/feature-gates/feature-gate-large-assignments.stderr

@@ -0,0 +1,12 @@
+error[E0658]: the `#[move_size_limit]` attribute is an experimental feature
+  --> $DIR/feature-gate-large-assignments.rs:3:1
+   |
+LL | #![move_size_limit = "42"]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #83518 <https://github.com/rust-lang/rust/issues/83518> for more information
+   = help: add `#![feature(large_assignments)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.