error: macro expansion ignores token `assert_eq` and any following
  --> $DIR/macro-in-expression-context.rs:12:9
   |
LL |         assert_eq!("B", "B");
   |         ^^^^^^^^^
...
LL |     foo!()
   |     ------ caused by the macro expansion here
   |
   = note: the usage of `foo!` is likely invalid in expression context
help: you might be missing a semicolon here
   |
LL |     foo!();
   |           +

warning: trailing semicolon in macro used in expression position
  --> $DIR/macro-in-expression-context.rs:5:29
   |
LL |         assert_eq!("A", "A");
   |                             ^
...
LL |     foo!()
   |     ------ in this macro invocation
   |
   = 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 #79813 <https://github.com/rust-lang/rust/issues/79813>
   = note: macro invocations at the end of a block are treated as expressions
   = note: to ignore the value produced by the macro, add a semicolon after the invocation of `foo`
   = note: `#[warn(semicolon_in_expressions_from_macros)]` on by default
   = note: this warning originates in the macro `foo` (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to 1 previous error; 1 warning emitted

Future incompatibility report: Future breakage diagnostic:
warning: trailing semicolon in macro used in expression position
  --> $DIR/macro-in-expression-context.rs:5:29
   |
LL |         assert_eq!("A", "A");
   |                             ^
...
LL |     foo!()
   |     ------ in this macro invocation
   |
   = 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 #79813 <https://github.com/rust-lang/rust/issues/79813>
   = note: macro invocations at the end of a block are treated as expressions
   = note: to ignore the value produced by the macro, add a semicolon after the invocation of `foo`
   = note: `#[warn(semicolon_in_expressions_from_macros)]` on by default
   = note: this warning originates in the macro `foo` (in Nightly builds, run with -Z macro-backtrace for more info)