Better error if the user tries to do assignment ... else

2 files changed, 35 insertions, 0 deletions

diff --git a/src/test/ui/let-else/let-else-destructuring.rs b/src/test/ui/let-else/let-else-destructuring.rs
new file mode 100644
index 00000000000..9a09c414ac8
--- /dev/null
+++ b/src/test/ui/let-else/let-else-destructuring.rs
@@ -0,0 +1,18 @@
+#![feature(let_else)]
+#[derive(Debug)]
+enum Foo {
+    Done,
+    Nested(Option<&'static Foo>),
+}
+
+fn walk(mut value: &Foo) {
+    loop {
+        println!("{:?}", value);
+        &Foo::Nested(Some(value)) = value else { break }; //~ ERROR invalid left-hand side of assignment
+        //~^ERROR <assignment> ... else { ... } is not allowed
+    }
+}
+
+fn main() {
+    walk(&Foo::Done);
+}
diff --git a/src/test/ui/let-else/let-else-destructuring.stderr b/src/test/ui/let-else/let-else-destructuring.stderr
new file mode 100644
index 00000000000..95efb711682
--- /dev/null
+++ b/src/test/ui/let-else/let-else-destructuring.stderr
@@ -0,0 +1,17 @@
+error: <assignment> ... else { ... } is not allowed
+  --> $DIR/let-else-destructuring.rs:11:9
+   |
+LL |         &Foo::Nested(Some(value)) = value else { break };
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0070]: invalid left-hand side of assignment
+  --> $DIR/let-else-destructuring.rs:11:35
+   |
+LL |         &Foo::Nested(Some(value)) = value else { break };
+   |         ------------------------- ^
+   |         |
+   |         cannot assign to this expression
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0070`.