add a failing test

Author: dianne

tests/ui/pattern/rfc-3627-match-ergonomics-2024/auxiliary/migration_lint_macros.rs

@@ -9,3 +9,10 @@ macro_rules! mixed_edition_pat {
         Some(mut $foo)
     };
 }
+
+#[macro_export]
+macro_rules! bind_ref {
+    ($foo:ident) => {
+        ref $foo
+    };
+}

tests/ui/pattern/rfc-3627-match-ergonomics-2024/migration_lint.fixed

@@ -239,4 +239,9 @@ fn main() {
     assert_type_eq(b, &0u32);
     assert_type_eq(c, &[0u32]);
     assert_type_eq(d, 0u32);
+
+    // Test that we use the correct message and suggestion style when pointing inside expansions.
+    let [migration_lint_macros::bind_ref!(a)] = &[0];
+    //~^ ERROR: binding modifiers may only be written when the default binding mode is `move`
+    assert_type_eq(a, &0u32);
 }

tests/ui/pattern/rfc-3627-match-ergonomics-2024/migration_lint.rs

@@ -239,4 +239,9 @@ fn main() {
     assert_type_eq(b, &0u32);
     assert_type_eq(c, &[0u32]);
     assert_type_eq(d, 0u32);
+
+    // Test that we use the correct message and suggestion style when pointing inside expansions.
+    let [migration_lint_macros::bind_ref!(a)] = &[0];
+    //~^ ERROR: binding modifiers may only be written when the default binding mode is `move`
+    assert_type_eq(a, &0u32);
 }

tests/ui/pattern/rfc-3627-match-ergonomics-2024/migration_lint.stderr

@@ -562,5 +562,19 @@ help: make the implied reference patterns explicit
 LL |     let [&Foo(&ref a @ [ref b]), &Foo(&ref c @ [d])] = [&Foo(&[0]); 2];
    |          +                       +
 
-error: aborting due to 29 previous errors
+error: reference patterns may only be written when the default binding mode is `move`
+  --> $DIR/migration_lint.rs:244:10
+   |
+LL |     let [migration_lint_macros::bind_ref!(a)] = &[0];
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ occurs within macro expansion
+   |
+   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2024/match-ergonomics.html>
+note: matching on a reference type with a non-reference pattern changes the default binding mode
+  --> $DIR/migration_lint.rs:244:9
+   |
+LL |     let [migration_lint_macros::bind_ref!(a)] = &[0];
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this matches on type `&_`
+   = note: this error originates in the macro `migration_lint_macros::bind_ref` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 30 previous errors