I think I find a error from page 520.

[sidgwick]

the code from P.520:

$( fields.insert($crate::ToString::to_string($key), json!($value)); )*

the code in this repository is:

$( fields.insert($crate::macros::ToString::to_string($key), json!($value)); )*

It should use the second version $crate::macros::ToString because ToString is private, just like HashMap?

😄

[jimblandy]

CC @jorendorff

Thank you for reporting the problem!

The book and the example code do disagree, as he says.