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-rw-r--r--tests/ui/nll/issue-24535-allow-mutable-borrow-in-match-guard.rs63
1 files changed, 63 insertions, 0 deletions
diff --git a/tests/ui/nll/issue-24535-allow-mutable-borrow-in-match-guard.rs b/tests/ui/nll/issue-24535-allow-mutable-borrow-in-match-guard.rs
new file mode 100644
index 000000000..ccfc8937f
--- /dev/null
+++ b/tests/ui/nll/issue-24535-allow-mutable-borrow-in-match-guard.rs
@@ -0,0 +1,63 @@
+// run-pass
+// This test illustrates that under NLL, we can remove our overly
+// conservative approach for disallowing mutations of match inputs.
+
+// See further discussion on rust-lang/rust#24535,
+// rust-lang/rfcs#1006, and rust-lang/rfcs#107
+
+#![feature(if_let_guard)]
+
+fn main() {
+ rust_issue_24535();
+ rfcs_issue_1006_1();
+ rfcs_issue_1006_2();
+}
+
+fn rust_issue_24535() {
+ fn compare(a: &u8, b: &mut u8) -> bool {
+ a == b
+ }
+
+ let a = 3u8;
+
+ match a {
+ 0 => panic!("nope"),
+ 3 if compare(&a, &mut 3) => (),
+ _ => panic!("nope"),
+ }
+
+ match a {
+ 0 => panic!("nope"),
+ 3 if let true = compare(&a, &mut 3) => (),
+ _ => panic!("nope"),
+ }
+}
+
+fn rfcs_issue_1006_1() {
+ let v = vec!["1".to_string(), "2".to_string(), "3".to_string()];
+ match Some(&v) {
+ Some(iv) if iv.iter().any(|x| &x[..]=="2") => true,
+ _ => panic!("nope"),
+ };
+}
+
+fn rfcs_issue_1006_2() {
+ #[inline(always)]
+ fn check<'a, I: Iterator<Item=&'a i32>>(mut i: I) -> bool {
+ i.any(|&x| x == 2)
+ }
+
+ let slice = [1, 2, 3];
+
+ match 42 {
+ _ if slice.iter().any(|&x| x == 2) => { true },
+ _ => { panic!("nope"); }
+ };
+
+ // (This match is just illustrating how easy it was to circumvent
+ // the checking performed for the previous `match`.)
+ match 42 {
+ _ if check(slice.iter()) => { true },
+ _ => { panic!("nope"); }
+ };
+}