Pass an owned value to log's methods?

[tisonkun]

Hi @KodrAus @Thomasdezeeuw,

According to the following code:

https://github.com/rust-lang/log/blob/6e1735597bb21c5d979a077395df85e1d633e077/src/__private_api.rs#L81

https://github.com/rust-lang/log/blob/6e1735597bb21c5d979a077395df85e1d633e077/src/__private_api.rs#L103-L105

Given that Record<'a> and Metadata<'a> already conatins all refs in their fields, and we have an owned value at the caller side, I'd like to know why we pass a ref &Record and &Metadata instead of Record<'a> and Metadata<'a>, to the log and enabled method.

I mean, is it possible to change (despite it's a breaking change, just think of it technically):

pub trait Log: Sync + Send {
    fn enabled(&self, metadata: &Metadata) -> bool;
    fn log(&self, record: &Record);
    fn flush(&self);
}

into

pub trait Log: Sync + Send {
    fn enabled(&self, metadata: Metadata<'_>) -> bool;
    fn log(&self, record: Record<'_>);
    fn flush(&self);
}

Any downside?