From 698f8c2f01ea549d77d7dc3338a12e04c11057b9 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Wed, 17 Apr 2024 14:02:58 +0200
Subject: Adding upstream version 1.64.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 .../ui/borrowck/borrow-immutable-upvar-mutation.rs | 56 ++++++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 src/test/ui/borrowck/borrow-immutable-upvar-mutation.rs

(limited to 'src/test/ui/borrowck/borrow-immutable-upvar-mutation.rs')

diff --git a/src/test/ui/borrowck/borrow-immutable-upvar-mutation.rs b/src/test/ui/borrowck/borrow-immutable-upvar-mutation.rs
new file mode 100644
index 000000000..e2f016614
--- /dev/null
+++ b/src/test/ui/borrowck/borrow-immutable-upvar-mutation.rs
@@ -0,0 +1,56 @@
+#![feature(unboxed_closures)]
+
+// Tests that we can't assign to or mutably borrow upvars from `Fn`
+// closures (issue #17780)
+
+fn set(x: &mut usize) {
+    *x = 5;
+}
+
+fn to_fn<A, F: Fn<A>>(f: F) -> F {
+    f
+}
+fn to_fn_mut<A, F: FnMut<A>>(f: F) -> F {
+    f
+}
+
+fn main() {
+    // By-ref captures
+    {
+        let mut x = 0;
+        let _f = to_fn(|| x = 42); //~ ERROR cannot assign
+
+        let mut y = 0;
+        let _g = to_fn(|| set(&mut y)); //~ ERROR cannot borrow
+
+        let mut z = 0;
+        let _h = to_fn_mut(|| {
+            set(&mut z);
+            to_fn(|| z = 42); //~ ERROR cannot assign
+        });
+    }
+
+    // By-value captures
+    {
+        let mut x = 0;
+        let _f = to_fn(move || x = 42); //~ ERROR cannot assign
+
+        let mut y = 0;
+        let _g = to_fn(move || set(&mut y)); //~ ERROR cannot borrow
+
+        let mut z = 0;
+        let _h = to_fn_mut(move || {
+            set(&mut z);
+            to_fn(move || z = 42);
+            //~^ ERROR cannot assign
+        });
+    }
+}
+
+fn foo() -> Box<dyn Fn() -> usize> {
+    let mut x = 0;
+    Box::new(move || {
+        x += 1; //~ ERROR cannot assign
+        x
+    })
+}
-- 
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