Convenience trait implementations on Ident

[hcpl]

Should Ident from proc-macro2 0.4 have following trait implementations like Ident from syn 0.13?

• From<&'a str>;
• From<Cow<'a, str>>;
• From<String>;
• AsRef<str> (however this one makes impl PartialEq<T: AsRef<str> + ?Sized> conflict with impl PartialEq).

Also in case of the last one, is a quote from: rust-lang/rust#50473

• Removed APIs: Ident::as_str, use Display impl for Ident instead.

relevant here (as in Ident::as_str being equivalent to <Ident as AsRef<str>>::as_ref)?

[alexcrichton]

The ones missing now are From and it's an explicit design decision of proc_macro the crate to always require spans to be specified when creating an Ident. I'd like to stick with that for now before we add From implementations which implicitly choose a span for you

[dtolnay]

Regarding AsRef: the compiler folks are not comfortable committing to an API that does &Ident ⟶ &str. rust-lang/rust#38356 (comment) explains.

From: over time these spans will get more important and we would prefer to require them explicitly.

[hcpl]

Thank you for the explanation. I was just concerned about the effort needed to port from the old proc-macro & quote & syn stack, but keeping API minimal is important too, so that's fine.

[fmckeogh]

I'm very sorry if this is the wrong place, but I'm updating a crate to use the latest version of proc-macro2 and I have a lot of the trait 'std::convert::From<std::string::String>' is not implemented for 'proc_macro2::Ident' errors occurring for lines like

let _name = Ident::from(format!("_{}", name.as_ref()));

I understand I need to use to_string() before as_ref() but what can I do to fix the implementation?

Thanks! :)

[hcpl]

I suppose name is an Ident. In that case, you can use

let _name = Ident::new(&name.to_string(), Span::call_site());

instead. Example on playground.

[fmckeogh]

Thank you so much! :)