1 files changed, 84 insertions, 0 deletions
diff --git a/tests/ui/binding/issue-53114-borrow-checks.rs b/tests/ui/binding/issue-53114-borrow-checks.rs
new file mode 100644
index 000000000..7646472f4
--- /dev/null
+++ b/tests/ui/binding/issue-53114-borrow-checks.rs
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+// 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.
+#![allow(irrefutable_let_patterns)]
+struct M;
+
+fn let_wild_gets_moved_expr() {
+    let m = M;
+    drop(m);
+    let _ = m; // accepted, and want it to continue to be
+
+    let mm = (M, M); // variation on above with `_` in substructure
+    let (_x, _) = mm;
+    let (_, _y) = mm;
+    let (_, _) = mm;
+}
+
+fn match_moved_expr_to_wild() {
+    let m = M;
+    drop(m);
+    match m { _ => { } } // #53114: should eventually be accepted too
+    //~^ ERROR [E0382]
+
+    let mm = (M, M); // variation on above with `_` in substructure
+    match mm { (_x, _) => { } }
+    match mm { (_, _y) => { } }
+    //~^ ERROR [E0382]
+    match mm { (_, _) => { } }
+    //~^ ERROR [E0382]
+}
+
+fn if_let_moved_expr_to_wild() {
+    let m = M;
+    drop(m);
+    if let _ = m { } // #53114: should eventually be accepted too
+    //~^ ERROR [E0382]
+
+    let mm = (M, M); // variation on above with `_` in substructure
+    if let (_x, _) = mm { }
+    if let (_, _y) = mm { }
+    //~^ ERROR [E0382]
+    if let (_, _) = mm { }
+    //~^ ERROR [E0382]
+}
+
+fn let_wild_gets_borrowed_expr() {
+    let mut m = M;
+    let r = &mut m;
+    let _ = m; // accepted, and want it to continue to be
+    // let _x = m; // (compare with this error.)
+    drop(r);
+
+    let mut mm = (M, M); // variation on above with `_` in substructure
+    let (r1, r2) = (&mut mm.0, &mut mm.1);
+    let (_, _) = mm;
+    drop((r1, r2));
+}
+
+fn match_borrowed_expr_to_wild() {
+    let mut m = M;
+    let r = &mut m;
+    match m { _ => {} } ; // accepted, and want it to continue to be
+    drop(r);
+
+    let mut mm = (M, M); // variation on above with `_` in substructure
+    let (r1, r2) = (&mut mm.0, &mut mm.1);
+    match mm { (_, _) => { } }
+    drop((r1, r2));
+}
+
+fn if_let_borrowed_expr_to_wild() {
+    let mut m = M;
+    let r = &mut m;
+    if let _ = m { } // accepted, and want it to continue to be
+    drop(r);
+
+    let mut mm = (M, M); // variation on above with `_` in substructure
+    let (r1, r2) = (&mut mm.0, &mut mm.1);
+    if let (_, _) = mm { }
+    drop((r1, r2));
+}
+
+fn main() { }