error: any use of this value will cause an error
  --> $DIR/const-external-macro-const-err.rs:12:5
   |
LL |     static_assert!(2 + 2 == 5);
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^ index out of bounds: the length is 1 but the index is 1
   |
   = note: `#[deny(const_err)]` on by default
   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
   = note: this error originates in the macro `static_assert` (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to previous error

Future incompatibility report: Future breakage diagnostic:
error: any use of this value will cause an error
  --> $DIR/const-external-macro-const-err.rs:12:5
   |
LL |     static_assert!(2 + 2 == 5);
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^ index out of bounds: the length is 1 but the index is 1
   |
   = note: `#[deny(const_err)]` on by default
   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
   = note: this error originates in the macro `static_assert` (in Nightly builds, run with -Z macro-backtrace for more info)