test: add ()=()=()=... to weird-exprs.rs

Author: slanterns

src/test/ui/weird-exprs.rs

@@ -1,6 +1,7 @@
 // run-pass
 
 #![feature(generators)]
+#![feature(destructuring_assignment)]
 
 #![allow(non_camel_case_types)]
 #![allow(dead_code)]
@@ -159,6 +160,11 @@ fn match_nested_if() {
     assert!(val);
 }
 
+fn empty_tuple_assignment() {
+    let val = ()=()=()=()=()=()=()=()=()=()=()=()=()=()=()=()=()=()=()=()=()=()=()=()=();
+    assert_eq!(val, ());
+}
+
 pub fn main() {
     strange();
     funny();
@@ -177,4 +183,5 @@ pub fn main() {
     r#match();
     i_yield();
     match_nested_if();
+    empty_tuple_assignment();
 }