Rollup merge of #43752 - arshiamufti:union-test, r=estebank

Add IRC's `!union union` as a test, addresses #43553

This pull request adds a new test, `union` to `weird-exprs.rs`.

src/test/run-pass/weird-exprs.rs

@@ -107,6 +107,10 @@ fn fishy() {
                String::<>::from::<>("><>").chars::<>().rev::<>().collect::<String>());
 }
 
+fn union() {
+    union union<'union> { union: &'union union<'union>, }
+}
+
 pub fn main() {
     strange();
     funny();
@@ -119,4 +123,5 @@ pub fn main() {
     dots();
     you_eight();
     fishy();
+    union();
 }