1 files changed, 51 insertions, 0 deletions
diff --git a/src/test/ui/binding/issue-53114-safety-checks.rs b/src/test/ui/binding/issue-53114-safety-checks.rs
new file mode 100644
index 000000000..d0eb28c57
--- /dev/null
+++ b/src/test/ui/binding/issue-53114-safety-checks.rs
@@ -0,0 +1,51 @@
+// Issue #53114: NLL's borrow check had some deviations from the old borrow
+// checker, and both had some deviations from our ideal state. This test
+// captures the behavior of how `_` bindings are handled with respect to how we
+// flag expressions that are meant to request unsafe blocks.
+
+#[derive(Copy, Clone)]
+struct I(i64);
+#[derive(Copy, Clone)]
+struct F(f64);
+
+union U { a: I, b: F }
+
+#[repr(packed)]
+struct P {
+    a: &'static i8,
+    b: &'static u32,
+}
+
+fn let_wild_gets_unsafe_field() {
+    let u1 = U { a: I(0) };
+    let u2 = U { a: I(1) };
+    let p = P { a: &2, b: &3 };
+    let _ = &p.b;  //~ ERROR    reference to packed field
+    //~^  WARN will become a hard error
+    let _ = u1.a;  // #53114: should eventually signal error as well
+    let _ = &u2.a; //~ ERROR  [E0133]
+
+    // variation on above with `_` in substructure
+    let (_,) = (&p.b,);  //~ ERROR     reference to packed field
+    //~^  WARN will become a hard error
+    let (_,) = (u1.a,);  //~ ERROR   [E0133]
+    let (_,) = (&u2.a,); //~ ERROR   [E0133]
+}
+
+fn match_unsafe_field_to_wild() {
+    let u1 = U { a: I(0) };
+    let u2 = U { a: I(1) };
+    let p = P { a: &2, b: &3 };
+    match &p.b  { _ => { } } //~ ERROR     reference to packed field
+    //~^  WARN will become a hard error
+    match u1.a  { _ => { } } //~ ERROR   [E0133]
+    match &u2.a { _ => { } } //~ ERROR   [E0133]
+
+    // variation on above with `_` in substructure
+    match (&p.b,)  { (_,) => { } } //~ ERROR     reference to packed field
+    //~^  WARN will become a hard error
+    match (u1.a,)  { (_,) => { } } //~ ERROR   [E0133]
+    match (&u2.a,) { (_,) => { } } //~ ERROR   [E0133]
+}
+
+fn main() { }