1 files changed, 36 insertions, 0 deletions
diff --git a/tests/ui/rust-2021/reserved-prefixes.rs b/tests/ui/rust-2021/reserved-prefixes.rs
new file mode 100644
index 00000000000..1994f25b6a5
--- /dev/null
+++ b/tests/ui/rust-2021/reserved-prefixes.rs
@@ -0,0 +1,36 @@
+// edition:2021
+
+macro_rules! demo2 {
+    ( $a:tt $b:tt ) => { println!("two tokens") };
+}
+
+macro_rules! demo3 {
+    ( $a:tt $b:tt $c:tt ) => { println!("three tokens") };
+}
+
+macro_rules! demo4 {
+    ( $a:tt $b:tt $c:tt $d:tt ) => { println!("four tokens") };
+}
+
+fn main() {
+    demo3!(foo#bar);   //~ ERROR prefix `foo` is unknown
+    demo2!(foo"bar");  //~ ERROR prefix `foo` is unknown
+    demo2!(foo'b');    //~ ERROR prefix `foo` is unknown
+
+    demo2!(foo'b);     //~ ERROR prefix `foo` is unknown
+    demo3!(foo# bar);  //~ ERROR prefix `foo` is unknown
+    demo4!(foo#! bar); //~ ERROR prefix `foo` is unknown
+    demo4!(foo## bar); //~ ERROR prefix `foo` is unknown
+
+    demo4!(foo#bar#);
+    //~^ ERROR prefix `foo` is unknown
+    //~| ERROR prefix `bar` is unknown
+
+    demo3!(foo # bar);
+    demo3!(foo #bar);
+    demo4!(foo!#bar);
+    demo4!(foo ##bar);
+
+    demo3!(r"foo"#bar);
+    demo3!(r#foo#bar);
+}