println!(123) works, but print!(123) and format!(123) do not

[niconii]

println! uses concat!($fmt, "\n") internally, which for literals converts $fmt into a string before concatenating. Because of this, println!(123) is accepted.

That said, rather than make println! as strict as print! and format!, it would be nice if format_args!(foo) could become shorthand for format_args!("{}", foo), somewhat similar to what panic! does.

[durka]

relevant #30143

[niconii]

Oh, whoops, is this a dupe, then? That seems more about making a breaking change to println! (and writeln!) to be less permissive about what they accept, whereas I'd personally like format_args! to be more permissive.

[durka]

I guess it's a duplicate, but the opinion in the other issue seemed to be that strictifying would be better than loosening. Loosening wouldn't be a breaking change, though. I guess an RFC would be required.

[alexcrichton]

Ah yeah I think this is a dupe of #30143 so I'm going to close in favor of that (which was previously decided as a whelp-this-would-be-nice-to-fix-but-2.0 kind of thing)