error: there is no argument named `crate`
  --> src/main.rs:3:18
   |
 3 |         println!(concat!("{", stringify!($x), "}"), $x=1);
   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
14 |     bar!();
   |     ------ in this macro invocation
   |
   = note: did you intend to capture a variable `crate` from the surrounding scope?
   = note: to avoid ambiguity, `format_args!` cannot capture variables when the format string is expanded from a macro
   = note: this error originates in the macro `concat` which comes from the expansion of the macro `bar` (in Nightly builds, run with -Z macro-backtrace for more info)

error: named argument never used
  --> src/main.rs:3:56
   |
 3 |         println!(concat!("{", stringify!($x), "}"), $x=1);
   |                  ---------------------------------     ^ named argument never used
   |                  |
   |                  formatting specifier missing
...
14 |     bar!();
   |     ------ in this macro invocation
   |
   = note: this error originates in the macro `foo` which comes from the expansion of the macro `bar` (in Nightly builds, run with -Z macro-backtrace for more info)

error: could not compile `playground` (bin "playground") due to 2 previous errors