error: `attr` rule argument matchers require parentheses
  --> $DIR/macro-attr-recovery.rs:5:9
   |
LL |     attr[$($args:tt)*] { $($body:tt)* } => {
   |         ^^^^^^^^^^^^^^
   |
help: the delimiters should be `(` and `)`
   |
LL -     attr[$($args:tt)*] { $($body:tt)* } => {
LL +     attr($($args:tt)*) { $($body:tt)* } => {
   |

error: attr: args="" body="struct S;"
  --> $DIR/macro-attr-recovery.rs:8:9
   |
LL | /         compile_error!(concat!(
LL | |             "attr: args=\"",
LL | |             stringify!($($args)*),
LL | |             "\" body=\"",
LL | |             stringify!($($body)*),
LL | |             "\"",
LL | |         ));
   | |__________^
...
LL |   #[attr]
   |   ------- in this attribute macro expansion
   |
   = note: this error originates in the attribute macro `attr` (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to 2 previous errors