Add a test for rust-lang#44127

Author: varkor

src/test/ui/issues/issue-44127.rs

@@ -0,0 +1,17 @@
+// run-pass
+
+#![feature(decl_macro)]
+
+pub struct Foo {
+    bar: u32,
+}
+pub macro pattern($a:pat) {
+    Foo { bar: $a }
+}
+
+fn main() {
+    match (Foo { bar: 3 }) {
+        pattern!(3) => println!("Test OK"),
+        _ => unreachable!(),
+    }
+}