Fix subslice capture in closure

2 files changed, 39 insertions, 0 deletions

diff --git a/tests/ui/closures/2229_closure_analysis/array_subslice.rs b/tests/ui/closures/2229_closure_analysis/array_subslice.rs
new file mode 100644
index 00000000000..5f244ea8936
--- /dev/null
+++ b/tests/ui/closures/2229_closure_analysis/array_subslice.rs
@@ -0,0 +1,13 @@
+// regression test for #109298
+// edition: 2021
+
+pub fn subslice_array(x: [u8; 3]) {
+    let f = || {
+        let [_x @ ..] = x;
+        let [ref y, ref mut z @ ..] = x; //~ ERROR cannot borrow `x[..]` as mutable
+    };
+
+    f(); //~ ERROR cannot borrow `f` as mutable
+}
+
+fn main() {}
diff --git a/tests/ui/closures/2229_closure_analysis/array_subslice.stderr b/tests/ui/closures/2229_closure_analysis/array_subslice.stderr
new file mode 100644
index 00000000000..888c60d5e91
--- /dev/null
+++ b/tests/ui/closures/2229_closure_analysis/array_subslice.stderr
@@ -0,0 +1,26 @@
+error[E0596]: cannot borrow `x[..]` as mutable, as `x` is not declared as mutable
+  --> $DIR/array_subslice.rs:7:21
+   |
+LL | pub fn subslice_array(x: [u8; 3]) {
+   |                       - help: consider changing this to be mutable: `mut x`
+...
+LL |         let [ref y, ref mut z @ ..] = x;
+   |                     ^^^^^^^^^ cannot borrow as mutable
+
+error[E0596]: cannot borrow `f` as mutable, as it is not declared as mutable
+  --> $DIR/array_subslice.rs:10:5
+   |
+LL |         let [ref y, ref mut z @ ..] = x;
+   |                                       - calling `f` requires mutable binding due to mutable borrow of `x`
+...
+LL |     f();
+   |     ^ cannot borrow as mutable
+   |
+help: consider changing this to be mutable
+   |
+LL |     let mut f = || {
+   |         +++
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0596`.