This is a test case to show the difference between Rust 1.45 and 1.46 in terms of how a particular type of error is reported when it is generated from within an attribute macro.

To demonstrate:

• rustup install 1.45.0
• rustup install 1.46.0
• cargo +1.45.0 run --example test
• cargo +1.46.0 run --example test

I know we are all extremely tired of 45, and nothing could be more welcome than 46, but in this corner case, 1.45 is slightly better.