diff --git a/src/test/ui/issues/issue-52240.rs b/src/test/ui/issues/issue-52240.rs new file mode 100644 index 00000000000..9ac7e9905da --- /dev/null +++ b/src/test/ui/issues/issue-52240.rs @@ -0,0 +1,16 @@ +// issue-52240: Can turn immutable into mut with `ref mut` + +enum Foo { + Bar(i32), +} + +fn main() { + let arr = vec!(Foo::Bar(0)); + if let (Some(Foo::Bar(ref mut val)), _) = (&arr.get(0), 0) { + //~^ ERROR cannot borrow field of immutable binding as mutable + *val = 9001; + } + match arr[0] { + Foo::Bar(ref s) => println!("{}", s) + } +} diff --git a/src/test/ui/issues/issue-52240.stderr b/src/test/ui/issues/issue-52240.stderr new file mode 100644 index 00000000000..c2c2524816d --- /dev/null +++ b/src/test/ui/issues/issue-52240.stderr @@ -0,0 +1,9 @@ +error[E0596]: cannot borrow field of immutable binding as mutable + --> $DIR/issue-52240.rs:9:27 + | +LL | if let (Some(Foo::Bar(ref mut val)), _) = (&arr.get(0), 0) { + | ^^^^^^^^^^^ cannot mutably borrow field of immutable binding + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0596`.