async-move-2015: Rename test, add comments, remove test output

Author: CohenArthur

tests/ui/proc-macro/auxiliary/async-move.rs renamed to tests/ui/proc-macro/auxiliary/edition-gated-async-move-syntax.rs

@@ -1,6 +1,10 @@
 // force-host
 // no-prefer-dynamic
 
+// Proc macro helper for issue #89699, used by tests/ui/proc-macro/edition-gated-async-move-
+// syntax-issue89699.rs, emitting an `async move` closure. This syntax is only available in
+// editions 2018 and up, but is used in edition 2015 in the test.
+
 #![crate_type = "proc-macro"]
 
 extern crate proc_macro;
@@ -31,6 +35,5 @@ pub fn foo(_attr: TokenStream, item: TokenStream) -> TokenStream {
         TokenTree::Group(Group::new(Delimiter::Parenthesis, TokenStream::new())),
         TokenTree::Group(Group::new(Delimiter::Brace, body)),
     ]);
-    eprintln!("{:?}", ret);
     ret
 }

tests/ui/proc-macro/edition-gated-async-move-syntax-issue89699.rs

@@ -0,0 +1,9 @@
+// aux-build:edition-gated-async-move-syntax.rs
+// edition: 2015
+
+// Non-regression test for issue #89699, where a proc-macro emitting syntax only available in edition 2018 and up (`async move`) is used on edition 2015
+
+extern crate edition_gated_async_move_syntax;
+
+#[edition_gated_async_move_syntax::foo]
+fn foo() {} //~ ERROR `async move` blocks are only allowed in Rust 2018 or later

tests/ui/proc-macro/edition-gated-async-move-syntax-issue89699.stderr

@@ -0,0 +1,8 @@
+error: `async move` blocks are only allowed in Rust 2018 or later
+  --> $DIR/edition-gated-async-move-syntax-issue89699.rs:9:1
+   |
+LL | fn foo() {}
+   | ^^
+
+error: aborting due to previous error
+