error: expected identifier
  --> $DIR/syntax-errors.rs:5:10
   |
LL |         ${concat()}
   |          ^^^^^^^^^^

error: `concat` must have at least two elements
  --> $DIR/syntax-errors.rs:8:11
   |
LL |         ${concat(aaaa)}
   |           ^^^^^^

error: expected identifier
  --> $DIR/syntax-errors.rs:11:10
   |
LL |         ${concat(aaaa,)}
   |          ^^^^^^^^^^^^^^^

error: expected identifier, found `1`
  --> $DIR/syntax-errors.rs:14:24
   |
LL |         ${concat(aaaa, 1)}
   |                        ^ help: try removing `1`

error: expected comma
  --> $DIR/syntax-errors.rs:19:10
   |
LL |         ${concat(aaaa aaaa)}
   |          ^^^^^^^^^^^^^^^^^^^

error: `concat` must have at least two elements
  --> $DIR/syntax-errors.rs:22:11
   |
LL |         ${concat($ex)}
   |           ^^^^^^

error: expected comma
  --> $DIR/syntax-errors.rs:28:10
   |
LL |         ${concat($ex, aaaa 123)}
   |          ^^^^^^^^^^^^^^^^^^^^^^^

error: expected identifier
  --> $DIR/syntax-errors.rs:31:10
   |
LL |         ${concat($ex, aaaa,)}
   |          ^^^^^^^^^^^^^^^^^^^^

error: expected identifier, found `123`
  --> $DIR/syntax-errors.rs:34:29
   |
LL |         ${concat($ex, aaaa, 123)}
   |                             ^^^ help: try removing `123`

error: `${concat(..)}` currently only accepts identifiers or meta-variables as parameters
  --> $DIR/syntax-errors.rs:25:19
   |
LL |         ${concat($ex, aaaa)}
   |                   ^^

error: variable `foo` is not recognized in meta-variable expression
  --> $DIR/syntax-errors.rs:41:30
   |
LL |         const ${concat(FOO, $foo)}: i32 = 2;
   |                              ^^^

error: aborting due to 11 previous errors