1 files changed, 115 insertions, 0 deletions
diff --git a/tests/ui/macros/metavar-expressions/concat-allowed-operations.rs b/tests/ui/macros/metavar-expressions/concat-allowed-operations.rs
new file mode 100644
index 00000000000..695a752fe17
--- /dev/null
+++ b/tests/ui/macros/metavar-expressions/concat-allowed-operations.rs
@@ -0,0 +1,115 @@
+//@ run-pass
+
+#![allow(dead_code, non_camel_case_types, non_upper_case_globals, unused_variables)]
+#![feature(macro_metavar_expr_concat)]
+
+macro_rules! create_things {
+    ($lhs:ident) => {
+        struct ${concat($lhs, _separated_idents_in_a_struct)} {
+            foo: i32,
+            ${concat($lhs, _separated_idents_in_a_field)}: i32,
+        }
+
+        mod ${concat($lhs, _separated_idents_in_a_module)} {
+            pub const FOO: () = ();
+        }
+
+        fn ${concat($lhs, _separated_idents_in_a_fn)}() {}
+    };
+}
+
+macro_rules! many_idents {
+    ($a:ident, $c:ident) => {
+        const ${concat($a, B, $c, D)}: i32 = 1;
+    };
+}
+
+macro_rules! valid_tts {
+    ($_0:tt, $_1:tt) => {
+        const ${concat($_0, $_1)}: i32 = 1;
+    }
+}
+
+macro_rules! without_dollar_sign_is_an_ident {
+    ($ident:ident) => {
+        const ${concat(VAR, ident)}: i32 = 1;
+        const ${concat(VAR, $ident)}: i32 = 2;
+    };
+}
+
+macro_rules! combinations {
+    ($ident:ident, $literal:literal, $tt_ident:tt, $tt_literal:tt) => {{
+        // tt ident
+        let ${concat($tt_ident, b)} = ();
+        let ${concat($tt_ident, _b)} = ();
+        let ${concat($tt_ident, "b")} = ();
+        let ${concat($tt_ident, $tt_ident)} = ();
+        let ${concat($tt_ident, $tt_literal)} = ();
+        let ${concat($tt_ident, $ident)} = ();
+        let ${concat($tt_ident, $literal)} = ();
+        // tt literal
+        let ${concat($tt_literal, b)} = ();
+        let ${concat($tt_literal, _b)} = ();
+        let ${concat($tt_literal, "b")} = ();
+        let ${concat($tt_literal, $tt_ident)} = ();
+        let ${concat($tt_literal, $tt_literal)} = ();
+        let ${concat($tt_literal, $ident)} = ();
+        let ${concat($tt_literal, $literal)} = ();
+
+        // ident (adhoc)
+        let ${concat(_b, b)} = ();
+        let ${concat(_b, _b)} = ();
+        let ${concat(_b, "b")} = ();
+        let ${concat(_b, $tt_ident)} = ();
+        let ${concat(_b, $tt_literal)} = ();
+        let ${concat(_b, $ident)} = ();
+        let ${concat(_b, $literal)} = ();
+        // ident (param)
+        let ${concat($ident, b)} = ();
+        let ${concat($ident, _b)} = ();
+        let ${concat($ident, "b")} = ();
+        let ${concat($ident, $tt_ident)} = ();
+        let ${concat($ident, $tt_literal)} = ();
+        let ${concat($ident, $ident)} = ();
+        let ${concat($ident, $literal)} = ();
+
+        // literal (adhoc)
+        let ${concat("a", b)} = ();
+        let ${concat("a", _b)} = ();
+        let ${concat("a", "b")} = ();
+        let ${concat("a", $tt_ident)} = ();
+        let ${concat("a", $tt_literal)} = ();
+        let ${concat("a", $ident)} = ();
+        let ${concat("a", $literal)} = ();
+        // literal (param)
+        let ${concat($literal, b)} = ();
+        let ${concat($literal, _b)} = ();
+        let ${concat($literal, "b")} = ();
+        let ${concat($literal, $tt_ident)} = ();
+        let ${concat($literal, $tt_literal)} = ();
+        let ${concat($literal, $ident)} = ();
+        let ${concat($literal, $literal)} = ();
+    }};
+}
+
+fn main() {
+    create_things!(behold);
+    behold_separated_idents_in_a_fn();
+    let _ = behold_separated_idents_in_a_module::FOO;
+    let _ = behold_separated_idents_in_a_struct {
+        foo: 1,
+        behold_separated_idents_in_a_field: 2,
+    };
+
+    many_idents!(A, C);
+    assert_eq!(ABCD, 1);
+
+    valid_tts!(X, YZ);
+    assert_eq!(XYZ, 1);
+
+    without_dollar_sign_is_an_ident!(_123);
+    assert_eq!(VARident, 1);
+    assert_eq!(VAR_123, 2);
+
+    combinations!(_hello, "a", b, "b");
+}